Data functions

Data functions allow you to dynamically set properties of a state or actions when they are instantiated using data from the projected process.

Functions are applied before a state transition to the executed action and the possible state transitions.

After a state transition, functions are applied to create the current state of the process. This includes the list of actions that can be executed in the state.

Functions

<ref>

Apply a JMESPath query to the process. You can retrieve and transform any part of the process, including the scenario and events.

YAML

actors:
  team:
    role: team
  client:
    properties:
      name: string
      email: !format email

actions:
  update_client:
    response: !ref scenario.actors.client
    update:
      set: actors.client
      value: !ref current.response | { name: name, email: email }

states:
  initial:
    transitions:
      - on: update_client
        by: team
        goto: ~
      - on: approve
        by: client
        if: !ref actors.client.email
        goto: (approved)
      - on: reject
        by: client
        goto: (rejected)

JSON

{
  "actors": {
    "team": {
      "role": "team"
    },
    "client": {
      "properties": {
        "name": "string",
        "email": {
          "type": "string",
          "format": "email"
        }
      }
    }
  },
  "actions": {
    "update_client": {
      "response": {
        "<ref>": "scenario.actors.client"
      },
      "update": {
        "set": "actors.client",
        "value": {
          "<ref>": "current.response | { name: name, email: email }"
        }
      }
    }
  },
  "states": {
    "initial": {
      "transitions": [
        {
          "on": "update_client",
          "by": "team",
          "goto": null
        },
        {
          "on": "approve",
          "by": "client",
          "if": {
            "<ref>": "actors.client.email"
          },
          "goto": "(approved)"
        },
        {
          "on": "reject",
          "by": "client",
          "goto": "(rejected)"
        }
      ]
    }
  }
}

It's important to know and understand how to use JMESPath expressions to unlock the full potential of LetsFlow. You can find more examples in the JMESPath documentation.

JMESPath

<tpl>

Parse text as a Mustache template.

When a function receives a simple string, it is treated as a Mustache template, with the process itself serving as the data (also known as the Mustache view).

You can explicitly specify both the template and the view for more flexibility. This allows you to apply a JSON query using <ref> to filter or transform the data before rendering the template.

YAML

actors:
  admin:
    role: admin
  client_*:
    properties:
      name: string
      approved: boolean

actions:
  send_sms:
    $schema: https://schemas.example.com/sms
    message: !tpl Hello {{ current.actor.name }}

states:
  instructions:
    admin: !tpl
      template: "{{#clients}}{{name}}: {{approved}}{{/}}"
      view: !ref "{ clients: actors.* | @[?role==null] }"

JSON

{
  "actors": {
    "admin": {
      "role": "admin"
    },
    "client_*": {
      "properties": {
        "name": "string",
        "approved": "boolean"
      }
    }
  },
  "actions": {
    "send_sms": {
      "$schema": "https://schemas.example.com/sms",
      "message": {
        "<tpl>": "Hello {{ current.actor.name }}"
      }
    }
  },
  "states": {
    "instructions": {
      "admin": {
        "<tpl>": {
          "template": "{{#clients}}{{name}}: {{approved}}{{/}}",
          "view": {
            "<ref>": "{ clients: actors.* | @[?role==null] }"
          }
        }
      }
    }
  }
}