JavaScript

Using JavaScript, implement robust validation logic, manipulate data structures, and perform efficient data transformations in Pipeline resolvers, Triggers and the Tailor DB.

Here are some examples of where you can utilize JavaScript:

Pipeline

You can use PostHook field in the Pipeline to return the object that can be used in the later steps.

Throwing a TailorErrorMessage in a pipeline step causes the pipeline execution to halt when the error is caught, and the API then returns the error message as the response.

Example:

PostHook: common.#Script & {
    Expr: """
        (() => {
            // throws an error if no heroes found
            if (args.characters.edges.length < 0) {
                throw new TailorErrorMessage("No heroes found")
            }
            return {
                "success": true,
                "heroes": args.characters.edges.map((c) => ({
                    "id": c.node.id,
                    "name": c.node.name
                }))
            }
        })()
    """
}

Triggers and Targets

You can write Javascript to check the condition for event based triggers.

Condition: common.#Script & {
    Expr: """
        args.namespaceName == "my-tailordb" && args.typeName == "PurchaseOrder"
    """
}

In the target type #TargetTailorGraphql, you can pass the input variables to the Graphql query as shown below.

Variables: common.#Script & {
    Expr: """
        ({
            input: {
                "quantity": args.newRecord.quantity,
                "purchaseOrderID": args.newRecord.id,
                "putAwayDate": args.newRecord.purchaseOrderDate
            }
        })"""
}

You can write custom logic using JavaScript in the URL and Body fields in the target type #TargetWebhook.

URL: common.#Script & {
    Expr: "\"https://hooks.slack.com/services/{service-name}/\""
}

Body: common.#Script & {
    Expr: """
        ({
            "text": "New Product Registration :tada:",
            "blocks": [
                {
                    "type": "section",
                    "text": {
                        "type": "mrkdwn",
                        "text": "*New Product Registration* :tada: " + args.newRecord.name
                    }
                }
            ]
        })
    """
}

Tailor DB

The example below demonstrates how to use JavaScript in Hooks to set a default value for the field. You can add custom logic to validate the input data and set default values.

Product: tailordb.#Type & {
	Name:        "Product"
	Description: "Product model"
	Fields: {
		...
		inactive:{
			Type:		tailordb.#TypeBool
			Description: "Field used to delete the record. Instead of deleting the record, we set this field to true. This is to keep the data integrity."
			Hooks: {
				Create: common.#Script & {
					Expr: "false"
				}
			}
		}
		...
	}
	...
}

Here's an example on how you can leverage the built-in support for console messages in JavaScript to debug and troubleshoot your code.

Product: tailordb.#Type & {
	Name:        "Product"
	Description: "Product model"
	Fields: {
		description: {
			Type:        tailordb.#TypeString
			Description: "Description of the product."
			Validate: [{
                Script: common.#Script & {
                    Expr: """
                        ((value, data) => {
                            console.log(value)
                            console.log(value.length)
                            console.log(data.name)
                            console.log(Object.keys(user))
                            Object.keys(user).forEach(function(key) {
								console.log(key, user[key], typeof user[key])
							})
                            return !(value.length < 40)
                        })(_value, _data)
                    """
                }
				Action: tailordb.#Permit.Deny
				ErrorMessage: "Description length should be less than 40 characters."
			}]
		}
		...
	}
	...
}

Run the Tailor platform in your local environment to debug the application and view console messages in the log. Contact us if you need more information about running the platform locally.

The Action will be evaluated when the Expr returns true.

The _value and _data arguments to the function represent the description field and the input data object for the new record.

Additionally, you can access user object which contains information about the user who created or updated the record.

The user object has the following fields:

  • id: ID of the user.
  • type: Type of the user Ex: machine_user.
  • workspace_id: Current workspace ID.
  • attributes: List of IDs ex: If the current user has admin rights then admin id is present in the list.
  • tenant_id: Tenant ID.