Resolver

Resolvers are custom GraphQL endpoints with business logic that execute on the Tailor Platform.

Overview

Resolvers provide:

Custom GraphQL queries and mutations
Type-safe input/output schemas
Access to TailorDB via Kysely query builder
User context for authentication/authorization

Comparison with Tailor Platform Pipeline Resolver

The SDK's Resolver is a simplified version of Tailor Platform's Pipeline Resolver.

Pipeline Resolver	SDK Resolver
Multiple steps with different operations	Single `body` function
Declarative step configuration	Imperative TypeScript code
Built-in TailorDB/GraphQL steps	Direct database access via Kysely
CEL expressions for data transformation	Native TypeScript transformations

Example Comparison

Pipeline Resolver (Tailor Platform native):

<span><span style="color: var(--shiki-token-keyword)">steps</span><span style="color: var(--shiki-token-keyword)">:</span></span>
<span><span style="color: var(--shiki-color-text)">  - </span><span style="color: var(--shiki-token-keyword)">name</span><span style="color: var(--shiki-token-keyword)">:</span><span style="color: var(--shiki-color-text)"> </span><span style="color: var(--shiki-token-string-expression)">getUser</span></span>
<span><span style="color: var(--shiki-color-text)">    </span><span style="color: var(--shiki-token-keyword)">operation</span><span style="color: var(--shiki-token-keyword)">:</span><span style="color: var(--shiki-color-text)"> </span><span style="color: var(--shiki-token-string-expression)">tailordb.query</span></span>
<span><span style="color: var(--shiki-color-text)">    </span><span style="color: var(--shiki-token-keyword)">params</span><span style="color: var(--shiki-token-keyword)">:</span></span>
<span><span style="color: var(--shiki-color-text)">      </span><span style="color: var(--shiki-token-keyword)">type</span><span style="color: var(--shiki-token-keyword)">:</span><span style="color: var(--shiki-color-text)"> </span><span style="color: var(--shiki-token-string-expression)">User</span></span>
<span><span style="color: var(--shiki-color-text)">      </span><span style="color: var(--shiki-token-keyword)">filter</span><span style="color: var(--shiki-token-keyword)">:</span></span>
<span><span style="color: var(--shiki-color-text)">        </span><span style="color: var(--shiki-token-keyword)">email</span><span style="color: var(--shiki-token-keyword)">:</span><span style="color: var(--shiki-color-text)"> { </span><span style="color: var(--shiki-token-keyword)">eq</span><span style="color: var(--shiki-token-keyword)">:</span><span style="color: var(--shiki-color-text)"> </span><span style="color: var(--shiki-token-string-expression)">&quot;{{ input.email }}&quot;</span><span style="color: var(--shiki-color-text)"> }</span></span>
<span><span style="color: var(--shiki-color-text)">  - </span><span style="color: var(--shiki-token-keyword)">name</span><span style="color: var(--shiki-token-keyword)">:</span><span style="color: var(--shiki-color-text)"> </span><span style="color: var(--shiki-token-string-expression)">updateAge</span></span>
<span><span style="color: var(--shiki-color-text)">    </span><span style="color: var(--shiki-token-keyword)">operation</span><span style="color: var(--shiki-token-keyword)">:</span><span style="color: var(--shiki-color-text)"> </span><span style="color: var(--shiki-token-string-expression)">tailordb.mutation</span></span>
<span><span style="color: var(--shiki-color-text)">    </span><span style="color: var(--shiki-token-keyword)">params</span><span style="color: var(--shiki-token-keyword)">:</span></span>
<span><span style="color: var(--shiki-color-text)">      </span><span style="color: var(--shiki-token-keyword)">type</span><span style="color: var(--shiki-token-keyword)">:</span><span style="color: var(--shiki-color-text)"> </span><span style="color: var(--shiki-token-string-expression)">User</span></span>
<span><span style="color: var(--shiki-color-text)">      </span><span style="color: var(--shiki-token-keyword)">id</span><span style="color: var(--shiki-token-keyword)">:</span><span style="color: var(--shiki-color-text)"> </span><span style="color: var(--shiki-token-string-expression)">&quot;{{ steps.getUser.id }}&quot;</span></span>
<span><span style="color: var(--shiki-color-text)">      </span><span style="color: var(--shiki-token-keyword)">input</span><span style="color: var(--shiki-token-keyword)">:</span></span>
<span><span style="color: var(--shiki-color-text)">        </span><span style="color: var(--shiki-token-keyword)">age</span><span style="color: var(--shiki-token-keyword)">:</span><span style="color: var(--shiki-color-text)"> </span><span style="color: var(--shiki-token-string-expression)">&quot;{{ steps.getUser.age + 1 }}&quot;</span></span>
<span></span>

Resolver (SDK):

<span><span style="color: var(--shiki-token-function)">createResolver</span><span style="color: var(--shiki-color-text)">({</span></span>
<span><span style="color: var(--shiki-color-text)">  name</span><span style="color: var(--shiki-token-keyword)">:</span><span style="color: var(--shiki-color-text)"> </span><span style="color: var(--shiki-token-string-expression)">&quot;incrementUserAge&quot;</span><span style="color: var(--shiki-token-punctuation)">,</span></span>
<span><span style="color: var(--shiki-color-text)">  operation</span><span style="color: var(--shiki-token-keyword)">:</span><span style="color: var(--shiki-color-text)"> </span><span style="color: var(--shiki-token-string-expression)">&quot;mutation&quot;</span><span style="color: var(--shiki-token-punctuation)">,</span></span>
<span><span style="color: var(--shiki-color-text)">  input</span><span style="color: var(--shiki-token-keyword)">:</span><span style="color: var(--shiki-color-text)"> { email</span><span style="color: var(--shiki-token-keyword)">:</span><span style="color: var(--shiki-color-text)"> </span><span style="color: var(--shiki-token-constant)">t</span><span style="color: var(--shiki-token-function)">.string</span><span style="color: var(--shiki-color-text)">() }</span><span style="color: var(--shiki-token-punctuation)">,</span></span>
<span><span style="color: var(--shiki-color-text)">  </span><span style="color: var(--shiki-token-function)">body</span><span style="color: var(--shiki-token-keyword)">:</span><span style="color: var(--shiki-color-text)"> </span><span style="color: var(--shiki-token-keyword)">async</span><span style="color: var(--shiki-color-text)"> (context) </span><span style="color: var(--shiki-token-keyword)">=&gt;</span><span style="color: var(--shiki-color-text)"> {</span></span>
<span><span style="color: var(--shiki-color-text)">    </span><span style="color: var(--shiki-token-keyword)">const</span><span style="color: var(--shiki-color-text)"> </span><span style="color: var(--shiki-token-constant)">db</span><span style="color: var(--shiki-color-text)"> </span><span style="color: var(--shiki-token-keyword)">=</span><span style="color: var(--shiki-color-text)"> </span><span style="color: var(--shiki-token-function)">getDB</span><span style="color: var(--shiki-color-text)">(</span><span style="color: var(--shiki-token-string-expression)">&quot;tailordb&quot;</span><span style="color: var(--shiki-color-text)">);</span></span>
<span><span style="color: var(--shiki-color-text)">    </span><span style="color: var(--shiki-token-keyword)">const</span><span style="color: var(--shiki-color-text)"> </span><span style="color: var(--shiki-token-constant)">user</span><span style="color: var(--shiki-color-text)"> </span><span style="color: var(--shiki-token-keyword)">=</span><span style="color: var(--shiki-color-text)"> </span><span style="color: var(--shiki-token-keyword)">await</span><span style="color: var(--shiki-color-text)"> db</span></span>
<span><span style="color: var(--shiki-color-text)">      </span><span style="color: var(--shiki-token-function)">.selectFrom</span><span style="color: var(--shiki-color-text)">(</span><span style="color: var(--shiki-token-string-expression)">&quot;User&quot;</span><span style="color: var(--shiki-color-text)">)</span></span>
<span><span style="color: var(--shiki-color-text)">      </span><span style="color: var(--shiki-token-function)">.selectAll</span><span style="color: var(--shiki-color-text)">()</span></span>
<span><span style="color: var(--shiki-color-text)">      </span><span style="color: var(--shiki-token-function)">.where</span><span style="color: var(--shiki-color-text)">(</span><span style="color: var(--shiki-token-string-expression)">&quot;email&quot;</span><span style="color: var(--shiki-token-punctuation)">,</span><span style="color: var(--shiki-color-text)"> </span><span style="color: var(--shiki-token-string-expression)">&quot;=&quot;</span><span style="color: var(--shiki-token-punctuation)">,</span><span style="color: var(--shiki-color-text)"> </span><span style="color: var(--shiki-token-constant)">context</span><span style="color: var(--shiki-color-text)">.</span><span style="color: var(--shiki-token-constant)">input</span><span style="color: var(--shiki-color-text)">.email)</span></span>
<span><span style="color: var(--shiki-color-text)">      </span><span style="color: var(--shiki-token-function)">.executeTakeFirstOrThrow</span><span style="color: var(--shiki-color-text)">();</span></span>
<span></span>
<span><span style="color: var(--shiki-color-text)">    </span><span style="color: var(--shiki-token-keyword)">await</span><span style="color: var(--shiki-color-text)"> db</span></span>
<span><span style="color: var(--shiki-color-text)">      </span><span style="color: var(--shiki-token-function)">.updateTable</span><span style="color: var(--shiki-color-text)">(</span><span style="color: var(--shiki-token-string-expression)">&quot;User&quot;</span><span style="color: var(--shiki-color-text)">)</span></span>
<span><span style="color: var(--shiki-color-text)">      </span><span style="color: var(--shiki-token-function)">.set</span><span style="color: var(--shiki-color-text)">({ age</span><span style="color: var(--shiki-token-keyword)">:</span><span style="color: var(--shiki-color-text)"> </span><span style="color: var(--shiki-token-constant)">user</span><span style="color: var(--shiki-color-text)">.age </span><span style="color: var(--shiki-token-keyword)">+</span><span style="color: var(--shiki-color-text)"> </span><span style="color: var(--shiki-token-constant)">1</span><span style="color: var(--shiki-color-text)"> })</span></span>
<span><span style="color: var(--shiki-color-text)">      </span><span style="color: var(--shiki-token-function)">.where</span><span style="color: var(--shiki-color-text)">(</span><span style="color: var(--shiki-token-string-expression)">&quot;id&quot;</span><span style="color: var(--shiki-token-punctuation)">,</span><span style="color: var(--shiki-color-text)"> </span><span style="color: var(--shiki-token-string-expression)">&quot;=&quot;</span><span style="color: var(--shiki-token-punctuation)">,</span><span style="color: var(--shiki-color-text)"> </span><span style="color: var(--shiki-token-constant)">user</span><span style="color: var(--shiki-color-text)">.id)</span></span>
<span><span style="color: var(--shiki-color-text)">      </span><span style="color: var(--shiki-token-function)">.execute</span><span style="color: var(--shiki-color-text)">();</span></span>
<span></span>
<span><span style="color: var(--shiki-color-text)">    </span><span style="color: var(--shiki-token-keyword)">return</span><span style="color: var(--shiki-color-text)"> { oldAge</span><span style="color: var(--shiki-token-keyword)">:</span><span style="color: var(--shiki-color-text)"> </span><span style="color: var(--shiki-token-constant)">user</span><span style="color: var(--shiki-color-text)">.age</span><span style="color: var(--shiki-token-punctuation)">,</span><span style="color: var(--shiki-color-text)"> newAge</span><span style="color: var(--shiki-token-keyword)">:</span><span style="color: var(--shiki-color-text)"> </span><span style="color: var(--shiki-token-constant)">user</span><span style="color: var(--shiki-color-text)">.age </span><span style="color: var(--shiki-token-keyword)">+</span><span style="color: var(--shiki-color-text)"> </span><span style="color: var(--shiki-token-constant)">1</span><span style="color: var(--shiki-color-text)"> };</span></span>
<span><span style="color: var(--shiki-color-text)">  }</span><span style="color: var(--shiki-token-punctuation)">,</span></span>
<span><span style="color: var(--shiki-color-text)">  output</span><span style="color: var(--shiki-token-keyword)">:</span><span style="color: var(--shiki-color-text)"> </span><span style="color: var(--shiki-token-constant)">t</span><span style="color: var(--shiki-token-function)">.object</span><span style="color: var(--shiki-color-text)">({ oldAge</span><span style="color: var(--shiki-token-keyword)">:</span><span style="color: var(--shiki-color-text)"> </span><span style="color: var(--shiki-token-constant)">t</span><span style="color: var(--shiki-token-function)">.int</span><span style="color: var(--shiki-color-text)">()</span><span style="color: var(--shiki-token-punctuation)">,</span><span style="color: var(--shiki-color-text)"> newAge</span><span style="color: var(--shiki-token-keyword)">:</span><span style="color: var(--shiki-color-text)"> </span><span style="color: var(--shiki-token-constant)">t</span><span style="color: var(--shiki-token-function)">.int</span><span style="color: var(--shiki-color-text)">() })</span><span style="color: var(--shiki-token-punctuation)">,</span></span>
<span><span style="color: var(--shiki-color-text)">});</span></span>
<span></span>

Creating a Resolver

Define resolvers in files matching glob patterns specified in tailor.config.ts.

<span><span style="color: var(--shiki-token-keyword)">import</span><span style="color: var(--shiki-color-text)"> { createResolver</span><span style="color: var(--shiki-token-punctuation)">,</span><span style="color: var(--shiki-color-text)"> t } </span><span style="color: var(--shiki-token-keyword)">from</span><span style="color: var(--shiki-color-text)"> </span><span style="color: var(--shiki-token-string-expression)">&quot;@tailor-platform/sdk&quot;</span><span style="color: var(--shiki-color-text)">;</span></span>
<span></span>
<span><span style="color: var(--shiki-token-keyword)">export</span><span style="color: var(--shiki-color-text)"> </span><span style="color: var(--shiki-token-keyword)">default</span><span style="color: var(--shiki-color-text)"> </span><span style="color: var(--shiki-token-function)">createResolver</span><span style="color: var(--shiki-color-text)">({</span></span>
<span><span style="color: var(--shiki-color-text)">  name</span><span style="color: var(--shiki-token-keyword)">:</span><span style="color: var(--shiki-color-text)"> </span><span style="color: var(--shiki-token-string-expression)">&quot;add&quot;</span><span style="color: var(--shiki-token-punctuation)">,</span></span>
<span><span style="color: var(--shiki-color-text)">  operation</span><span style="color: var(--shiki-token-keyword)">:</span><span style="color: var(--shiki-color-text)"> </span><span style="color: var(--shiki-token-string-expression)">&quot;query&quot;</span><span style="color: var(--shiki-token-punctuation)">,</span></span>
<span><span style="color: var(--shiki-color-text)">  input</span><span style="color: var(--shiki-token-keyword)">:</span><span style="color: var(--shiki-color-text)"> {</span></span>
<span><span style="color: var(--shiki-color-text)">    left</span><span style="color: var(--shiki-token-keyword)">:</span><span style="color: var(--shiki-color-text)"> </span><span style="color: var(--shiki-token-constant)">t</span><span style="color: var(--shiki-token-function)">.int</span><span style="color: var(--shiki-color-text)">()</span><span style="color: var(--shiki-token-punctuation)">,</span></span>
<span><span style="color: var(--shiki-color-text)">    right</span><span style="color: var(--shiki-token-keyword)">:</span><span style="color: var(--shiki-color-text)"> </span><span style="color: var(--shiki-token-constant)">t</span><span style="color: var(--shiki-token-function)">.int</span><span style="color: var(--shiki-color-text)">()</span><span style="color: var(--shiki-token-punctuation)">,</span></span>
<span><span style="color: var(--shiki-color-text)">  }</span><span style="color: var(--shiki-token-punctuation)">,</span></span>
<span><span style="color: var(--shiki-color-text)">  </span><span style="color: var(--shiki-token-function)">body</span><span style="color: var(--shiki-token-keyword)">:</span><span style="color: var(--shiki-color-text)"> (context) </span><span style="color: var(--shiki-token-keyword)">=&gt;</span><span style="color: var(--shiki-color-text)"> {</span></span>
<span><span style="color: var(--shiki-color-text)">    </span><span style="color: var(--shiki-token-keyword)">return</span><span style="color: var(--shiki-color-text)"> {</span></span>
<span><span style="color: var(--shiki-color-text)">      result</span><span style="color: var(--shiki-token-keyword)">:</span><span style="color: var(--shiki-color-text)"> </span><span style="color: var(--shiki-token-constant)">context</span><span style="color: var(--shiki-color-text)">.</span><span style="color: var(--shiki-token-constant)">input</span><span style="color: var(--shiki-color-text)">.left </span><span style="color: var(--shiki-token-keyword)">+</span><span style="color: var(--shiki-color-text)"> </span><span style="color: var(--shiki-token-constant)">context</span><span style="color: var(--shiki-color-text)">.</span><span style="color: var(--shiki-token-constant)">input</span><span style="color: var(--shiki-color-text)">.right</span><span style="color: var(--shiki-token-punctuation)">,</span></span>
<span><span style="color: var(--shiki-color-text)">    };</span></span>
<span><span style="color: var(--shiki-color-text)">  }</span><span style="color: var(--shiki-token-punctuation)">,</span></span>
<span><span style="color: var(--shiki-color-text)">  output</span><span style="color: var(--shiki-token-keyword)">:</span><span style="color: var(--shiki-color-text)"> </span><span style="color: var(--shiki-token-constant)">t</span><span style="color: var(--shiki-token-function)">.object</span><span style="color: var(--shiki-color-text)">({</span></span>
<span><span style="color: var(--shiki-color-text)">    result</span><span style="color: var(--shiki-token-keyword)">:</span><span style="color: var(--shiki-color-text)"> </span><span style="color: var(--shiki-token-constant)">t</span><span style="color: var(--shiki-token-function)">.int</span><span style="color: var(--shiki-color-text)">()</span><span style="color: var(--shiki-token-punctuation)">,</span></span>
<span><span style="color: var(--shiki-color-text)">  })</span><span style="color: var(--shiki-token-punctuation)">,</span></span>
<span><span style="color: var(--shiki-color-text)">});</span></span>
<span></span>

Input/Output Schemas

Define input/output schemas using methods of t object. Basic usage and supported field types are the same as TailorDB. TailorDB-specific options (e.g., index, relation) are not supported.

You can reuse fields defined with db object, but note that unsupported options will be ignored:

<span><span style="color: var(--shiki-token-keyword)">const</span><span style="color: var(--shiki-color-text)"> </span><span style="color: var(--shiki-token-constant)">user</span><span style="color: var(--shiki-color-text)"> </span><span style="color: var(--shiki-token-keyword)">=</span><span style="color: var(--shiki-color-text)"> </span><span style="color: var(--shiki-token-constant)">db</span><span style="color: var(--shiki-token-function)">.type</span><span style="color: var(--shiki-color-text)">(</span><span style="color: var(--shiki-token-string-expression)">&quot;User&quot;</span><span style="color: var(--shiki-token-punctuation)">,</span><span style="color: var(--shiki-color-text)"> {</span></span>
<span><span style="color: var(--shiki-color-text)">  name</span><span style="color: var(--shiki-token-keyword)">:</span><span style="color: var(--shiki-color-text)"> </span><span style="color: var(--shiki-token-constant)">db</span><span style="color: var(--shiki-token-function)">.string</span><span style="color: var(--shiki-color-text)">()</span><span style="color: var(--shiki-token-function)">.unique</span><span style="color: var(--shiki-color-text)">()</span><span style="color: var(--shiki-token-punctuation)">,</span></span>
<span><span style="color: var(--shiki-color-text)">  age</span><span style="color: var(--shiki-token-keyword)">:</span><span style="color: var(--shiki-color-text)"> </span><span style="color: var(--shiki-token-constant)">db</span><span style="color: var(--shiki-token-function)">.int</span><span style="color: var(--shiki-color-text)">()</span><span style="color: var(--shiki-token-punctuation)">,</span></span>
<span><span style="color: var(--shiki-color-text)">});</span></span>
<span></span>
<span><span style="color: var(--shiki-token-function)">createResolver</span><span style="color: var(--shiki-color-text)">({</span></span>
<span><span style="color: var(--shiki-color-text)">  input</span><span style="color: var(--shiki-token-keyword)">:</span><span style="color: var(--shiki-color-text)"> {</span></span>
<span><span style="color: var(--shiki-color-text)">    name</span><span style="color: var(--shiki-token-keyword)">:</span><span style="color: var(--shiki-color-text)"> </span><span style="color: var(--shiki-token-constant)">user</span><span style="color: var(--shiki-color-text)">.</span><span style="color: var(--shiki-token-constant)">fields</span><span style="color: var(--shiki-color-text)">.name</span><span style="color: var(--shiki-token-punctuation)">,</span></span>
<span><span style="color: var(--shiki-color-text)">  }</span><span style="color: var(--shiki-token-punctuation)">,</span></span>
<span><span style="color: var(--shiki-color-text)">});</span></span>
<span></span>

Input Validation

Add validation rules to input fields using the validate method:

<span><span style="color: var(--shiki-token-function)">createResolver</span><span style="color: var(--shiki-color-text)">({</span></span>
<span><span style="color: var(--shiki-color-text)">  name</span><span style="color: var(--shiki-token-keyword)">:</span><span style="color: var(--shiki-color-text)"> </span><span style="color: var(--shiki-token-string-expression)">&quot;createUser&quot;</span><span style="color: var(--shiki-token-punctuation)">,</span></span>
<span><span style="color: var(--shiki-color-text)">  operation</span><span style="color: var(--shiki-token-keyword)">:</span><span style="color: var(--shiki-color-text)"> </span><span style="color: var(--shiki-token-string-expression)">&quot;mutation&quot;</span><span style="color: var(--shiki-token-punctuation)">,</span></span>
<span><span style="color: var(--shiki-color-text)">  input</span><span style="color: var(--shiki-token-keyword)">:</span><span style="color: var(--shiki-color-text)"> {</span></span>
<span><span style="color: var(--shiki-color-text)">    email</span><span style="color: var(--shiki-token-keyword)">:</span><span style="color: var(--shiki-color-text)"> t</span></span>
<span><span style="color: var(--shiki-color-text)">      </span><span style="color: var(--shiki-token-function)">.string</span><span style="color: var(--shiki-color-text)">()</span></span>
<span><span style="color: var(--shiki-color-text)">      </span><span style="color: var(--shiki-token-function)">.validate</span><span style="color: var(--shiki-color-text)">(</span></span>
<span><span style="color: var(--shiki-color-text)">        ({ value }) </span><span style="color: var(--shiki-token-keyword)">=&gt;</span><span style="color: var(--shiki-color-text)"> </span><span style="color: var(--shiki-token-constant)">value</span><span style="color: var(--shiki-token-function)">.includes</span><span style="color: var(--shiki-color-text)">(</span><span style="color: var(--shiki-token-string-expression)">&quot;@&quot;</span><span style="color: var(--shiki-color-text)">)</span><span style="color: var(--shiki-token-punctuation)">,</span></span>
<span><span style="color: var(--shiki-color-text)">        [</span></span>
<span><span style="color: var(--shiki-color-text)">          ({ value }) </span><span style="color: var(--shiki-token-keyword)">=&gt;</span><span style="color: var(--shiki-color-text)"> </span><span style="color: var(--shiki-token-constant)">value</span><span style="color: var(--shiki-color-text)">.</span><span style="color: var(--shiki-token-constant)">length</span><span style="color: var(--shiki-color-text)"> </span><span style="color: var(--shiki-token-keyword)">&lt;=</span><span style="color: var(--shiki-color-text)"> </span><span style="color: var(--shiki-token-constant)">255</span><span style="color: var(--shiki-token-punctuation)">,</span></span>
<span><span style="color: var(--shiki-color-text)">          </span><span style="color: var(--shiki-token-string-expression)">&quot;Email must be 255 characters or less&quot;</span><span style="color: var(--shiki-token-punctuation)">,</span></span>
<span><span style="color: var(--shiki-color-text)">        ]</span><span style="color: var(--shiki-token-punctuation)">,</span></span>
<span><span style="color: var(--shiki-color-text)">      )</span><span style="color: var(--shiki-token-punctuation)">,</span></span>
<span><span style="color: var(--shiki-color-text)">    age</span><span style="color: var(--shiki-token-keyword)">:</span><span style="color: var(--shiki-color-text)"> </span><span style="color: var(--shiki-token-constant)">t</span><span style="color: var(--shiki-token-function)">.int</span><span style="color: var(--shiki-color-text)">()</span><span style="color: var(--shiki-token-function)">.validate</span><span style="color: var(--shiki-color-text)">(({ value }) </span><span style="color: var(--shiki-token-keyword)">=&gt;</span><span style="color: var(--shiki-color-text)"> value </span><span style="color: var(--shiki-token-keyword)">&gt;=</span><span style="color: var(--shiki-color-text)"> </span><span style="color: var(--shiki-token-constant)">0</span><span style="color: var(--shiki-color-text)"> </span><span style="color: var(--shiki-token-keyword)">&amp;&amp;</span><span style="color: var(--shiki-color-text)"> value </span><span style="color: var(--shiki-token-keyword)">&lt;=</span><span style="color: var(--shiki-color-text)"> </span><span style="color: var(--shiki-token-constant)">150</span><span style="color: var(--shiki-color-text)">)</span><span style="color: var(--shiki-token-punctuation)">,</span></span>
<span><span style="color: var(--shiki-color-text)">  }</span><span style="color: var(--shiki-token-punctuation)">,</span></span>
<span><span style="color: var(--shiki-color-text)">  </span><span style="color: var(--shiki-token-function)">body</span><span style="color: var(--shiki-token-keyword)">:</span><span style="color: var(--shiki-color-text)"> (context) </span><span style="color: var(--shiki-token-keyword)">=&gt;</span><span style="color: var(--shiki-color-text)"> {</span></span>
<span><span style="color: var(--shiki-color-text)">    </span><span style="color: var(--shiki-token-comment)">// Input is validated before body executes</span></span>
<span><span style="color: var(--shiki-color-text)">    </span><span style="color: var(--shiki-token-keyword)">return</span><span style="color: var(--shiki-color-text)"> { email</span><span style="color: var(--shiki-token-keyword)">:</span><span style="color: var(--shiki-color-text)"> </span><span style="color: var(--shiki-token-constant)">context</span><span style="color: var(--shiki-color-text)">.</span><span style="color: var(--shiki-token-constant)">input</span><span style="color: var(--shiki-color-text)">.email };</span></span>
<span><span style="color: var(--shiki-color-text)">  }</span><span style="color: var(--shiki-token-punctuation)">,</span></span>
<span><span style="color: var(--shiki-color-text)">  output</span><span style="color: var(--shiki-token-keyword)">:</span><span style="color: var(--shiki-color-text)"> </span><span style="color: var(--shiki-token-constant)">t</span><span style="color: var(--shiki-token-function)">.object</span><span style="color: var(--shiki-color-text)">({ email</span><span style="color: var(--shiki-token-keyword)">:</span><span style="color: var(--shiki-color-text)"> </span><span style="color: var(--shiki-token-constant)">t</span><span style="color: var(--shiki-token-function)">.string</span><span style="color: var(--shiki-color-text)">() })</span><span style="color: var(--shiki-token-punctuation)">,</span></span>
<span><span style="color: var(--shiki-color-text)">});</span></span>
<span></span>

Validation functions receive:

value - The field value being validated
data - The entire input object
user - The user performing the operation

You can specify validation as:

A function returning boolean (uses default error message)
A tuple of [function, errorMessage] for custom error messages
Multiple validators (pass multiple arguments to validate)

Body Function

Define actual resolver logic in the body function. Function arguments include:

input - Input data from GraphQL request
user - User performing the operation

Using Kysely for Database Access

If you're generating Kysely types with a generator, you can use getDB to execute typed queries:

<span><span style="color: var(--shiki-token-keyword)">import</span><span style="color: var(--shiki-color-text)"> { getDB } </span><span style="color: var(--shiki-token-keyword)">from</span><span style="color: var(--shiki-color-text)"> </span><span style="color: var(--shiki-token-string-expression)">&quot;../generated/tailordb&quot;</span><span style="color: var(--shiki-color-text)">;</span></span>
<span></span>
<span><span style="color: var(--shiki-token-function)">createResolver</span><span style="color: var(--shiki-color-text)">({</span></span>
<span><span style="color: var(--shiki-color-text)">  name</span><span style="color: var(--shiki-token-keyword)">:</span><span style="color: var(--shiki-color-text)"> </span><span style="color: var(--shiki-token-string-expression)">&quot;getUser&quot;</span><span style="color: var(--shiki-token-punctuation)">,</span></span>
<span><span style="color: var(--shiki-color-text)">  operation</span><span style="color: var(--shiki-token-keyword)">:</span><span style="color: var(--shiki-color-text)"> </span><span style="color: var(--shiki-token-string-expression)">&quot;query&quot;</span><span style="color: var(--shiki-token-punctuation)">,</span></span>
<span><span style="color: var(--shiki-color-text)">  input</span><span style="color: var(--shiki-token-keyword)">:</span><span style="color: var(--shiki-color-text)"> {</span></span>
<span><span style="color: var(--shiki-color-text)">    name</span><span style="color: var(--shiki-token-keyword)">:</span><span style="color: var(--shiki-color-text)"> </span><span style="color: var(--shiki-token-constant)">t</span><span style="color: var(--shiki-token-function)">.string</span><span style="color: var(--shiki-color-text)">()</span><span style="color: var(--shiki-token-punctuation)">,</span></span>
<span><span style="color: var(--shiki-color-text)">  }</span><span style="color: var(--shiki-token-punctuation)">,</span></span>
<span><span style="color: var(--shiki-color-text)">  </span><span style="color: var(--shiki-token-function)">body</span><span style="color: var(--shiki-token-keyword)">:</span><span style="color: var(--shiki-color-text)"> </span><span style="color: var(--shiki-token-keyword)">async</span><span style="color: var(--shiki-color-text)"> (context) </span><span style="color: var(--shiki-token-keyword)">=&gt;</span><span style="color: var(--shiki-color-text)"> {</span></span>
<span><span style="color: var(--shiki-color-text)">    </span><span style="color: var(--shiki-token-keyword)">const</span><span style="color: var(--shiki-color-text)"> </span><span style="color: var(--shiki-token-constant)">db</span><span style="color: var(--shiki-color-text)"> </span><span style="color: var(--shiki-token-keyword)">=</span><span style="color: var(--shiki-color-text)"> </span><span style="color: var(--shiki-token-function)">getDB</span><span style="color: var(--shiki-color-text)">(</span><span style="color: var(--shiki-token-string-expression)">&quot;tailordb&quot;</span><span style="color: var(--shiki-color-text)">);</span></span>
<span><span style="color: var(--shiki-color-text)">    </span><span style="color: var(--shiki-token-keyword)">const</span><span style="color: var(--shiki-color-text)"> </span><span style="color: var(--shiki-token-constant)">result</span><span style="color: var(--shiki-color-text)"> </span><span style="color: var(--shiki-token-keyword)">=</span><span style="color: var(--shiki-color-text)"> </span><span style="color: var(--shiki-token-keyword)">await</span><span style="color: var(--shiki-color-text)"> db</span></span>
<span><span style="color: var(--shiki-color-text)">      </span><span style="color: var(--shiki-token-function)">.selectFrom</span><span style="color: var(--shiki-color-text)">(</span><span style="color: var(--shiki-token-string-expression)">&quot;User&quot;</span><span style="color: var(--shiki-color-text)">)</span></span>
<span><span style="color: var(--shiki-color-text)">      </span><span style="color: var(--shiki-token-function)">.select</span><span style="color: var(--shiki-color-text)">(</span><span style="color: var(--shiki-token-string-expression)">&quot;id&quot;</span><span style="color: var(--shiki-color-text)">)</span></span>
<span><span style="color: var(--shiki-color-text)">      </span><span style="color: var(--shiki-token-function)">.where</span><span style="color: var(--shiki-color-text)">(</span><span style="color: var(--shiki-token-string-expression)">&quot;name&quot;</span><span style="color: var(--shiki-token-punctuation)">,</span><span style="color: var(--shiki-color-text)"> </span><span style="color: var(--shiki-token-string-expression)">&quot;=&quot;</span><span style="color: var(--shiki-token-punctuation)">,</span><span style="color: var(--shiki-color-text)"> </span><span style="color: var(--shiki-token-constant)">context</span><span style="color: var(--shiki-color-text)">.</span><span style="color: var(--shiki-token-constant)">input</span><span style="color: var(--shiki-color-text)">.name)</span></span>
<span><span style="color: var(--shiki-color-text)">      </span><span style="color: var(--shiki-token-function)">.limit</span><span style="color: var(--shiki-color-text)">(</span><span style="color: var(--shiki-token-constant)">1</span><span style="color: var(--shiki-color-text)">)</span></span>
<span><span style="color: var(--shiki-color-text)">      </span><span style="color: var(--shiki-token-function)">.executeTakeFirstOrThrow</span><span style="color: var(--shiki-color-text)">();</span></span>
<span><span style="color: var(--shiki-color-text)">    </span><span style="color: var(--shiki-token-keyword)">return</span><span style="color: var(--shiki-color-text)"> {</span></span>
<span><span style="color: var(--shiki-color-text)">      result</span><span style="color: var(--shiki-token-keyword)">:</span><span style="color: var(--shiki-color-text)"> </span><span style="color: var(--shiki-token-constant)">result</span><span style="color: var(--shiki-color-text)">.id</span><span style="color: var(--shiki-token-punctuation)">,</span></span>
<span><span style="color: var(--shiki-color-text)">    };</span></span>
<span><span style="color: var(--shiki-color-text)">  }</span><span style="color: var(--shiki-token-punctuation)">,</span></span>
<span><span style="color: var(--shiki-color-text)">  output</span><span style="color: var(--shiki-token-keyword)">:</span><span style="color: var(--shiki-color-text)"> </span><span style="color: var(--shiki-token-constant)">t</span><span style="color: var(--shiki-token-function)">.object</span><span style="color: var(--shiki-color-text)">({</span></span>
<span><span style="color: var(--shiki-color-text)">    result</span><span style="color: var(--shiki-token-keyword)">:</span><span style="color: var(--shiki-color-text)"> </span><span style="color: var(--shiki-token-constant)">t</span><span style="color: var(--shiki-token-function)">.uuid</span><span style="color: var(--shiki-color-text)">()</span><span style="color: var(--shiki-token-punctuation)">,</span></span>
<span><span style="color: var(--shiki-color-text)">  })</span><span style="color: var(--shiki-token-punctuation)">,</span></span>
<span><span style="color: var(--shiki-color-text)">});</span></span>
<span></span>

Query vs Mutation

Use operation: "query" for read operations and operation: "mutation" for write operations:

<span><span style="color: var(--shiki-token-comment)">// Query - for reading data</span></span>
<span><span style="color: var(--shiki-token-function)">createResolver</span><span style="color: var(--shiki-color-text)">({</span></span>
<span><span style="color: var(--shiki-color-text)">  name</span><span style="color: var(--shiki-token-keyword)">:</span><span style="color: var(--shiki-color-text)"> </span><span style="color: var(--shiki-token-string-expression)">&quot;getUsers&quot;</span><span style="color: var(--shiki-token-punctuation)">,</span></span>
<span><span style="color: var(--shiki-color-text)">  operation</span><span style="color: var(--shiki-token-keyword)">:</span><span style="color: var(--shiki-color-text)"> </span><span style="color: var(--shiki-token-string-expression)">&quot;query&quot;</span><span style="color: var(--shiki-token-punctuation)">,</span></span>
<span><span style="color: var(--shiki-color-text)">  </span><span style="color: var(--shiki-token-comment)">// ...</span></span>
<span><span style="color: var(--shiki-color-text)">});</span></span>
<span></span>
<span><span style="color: var(--shiki-token-comment)">// Mutation - for creating, updating, or deleting data</span></span>
<span><span style="color: var(--shiki-token-function)">createResolver</span><span style="color: var(--shiki-color-text)">({</span></span>
<span><span style="color: var(--shiki-color-text)">  name</span><span style="color: var(--shiki-token-keyword)">:</span><span style="color: var(--shiki-color-text)"> </span><span style="color: var(--shiki-token-string-expression)">&quot;createUser&quot;</span><span style="color: var(--shiki-token-punctuation)">,</span></span>
<span><span style="color: var(--shiki-color-text)">  operation</span><span style="color: var(--shiki-token-keyword)">:</span><span style="color: var(--shiki-color-text)"> </span><span style="color: var(--shiki-token-string-expression)">&quot;mutation&quot;</span><span style="color: var(--shiki-token-punctuation)">,</span></span>
<span><span style="color: var(--shiki-color-text)">  </span><span style="color: var(--shiki-token-comment)">// ...</span></span>
<span><span style="color: var(--shiki-color-text)">});</span></span>
<span></span>