Codeblock flow-node

This document describes a Codeblock flow-node and provides information on Codeblock flow-node.

Name

Description

Codeblock

A flow-node that can be used for executing user code and returns the response. This node allows custom business logic to be execute as part of the flow.

The Codeblock flow-node configuration, metadata, functionality, methods, parameters, and outputs for the Greet Codeblock flow-node are described in the following sections. Each method in a Codeblock flow-node corresponds to a single codeblock. The Greet Codeblock flow-node is created when a new application is created, but it can be deleted.

Instance configuration (config)

Property

Description

Required

Type

method

The name of the Codeblock to execute.

yes

string

The typical usage of code block flow-nodes involves setting parameters, mapping responses, and setting required configs as noted in the example below.

Configuration example

"block.0": {
 "type": "Codeblock",
 "config": {
   "method": "Greet"
 },
 "parameters": [
   {
     "name": "username",
     "value": "$.params.username"
   }
 ],
 "response": {
   "context": {
     "$": "greeting"
   },
   "routes": null
 }
}

Metadata

Codeblock metadata should be included in the /codeblocks directory of an API Builder Project. It is defined as a JSON file with the following properties:

Property

Description

Required

Type

name

The name of the Codeblock.

yes

string

description

The description of the Codeblock.

yes

string

path

The relative path to the function to be invoked.

yes

string

Metadata example

{
  "name": "Greet",
  "description": "Some codeblock to run with Greet flow",
  "path": "Greet.js"
}

 The functional part of a Codeblock should be a .js file which exports a function of the following signature:

invoke(apibuilder, params, cb);

  • apibuilder <APIBuilder> - The API Builder instance.

  • params <Object> - Key/value pairs of parameters passed to the node instance.

  • cb <Function> - Callback.

    • err - Error. Passing this will cause the flow to cease processing and a 500 error to be returned from the endpoint which called it.

    • response - The data to be returned as the node response.

Icon

Most of the time errors should be returned in the callback as a standard response. Using the first parameter to return errors is the same as throwing an error in the Codeblock and should rarely need to be used.

Functionality example

 

function invoke(apibuilder, params, cb) {
    const salutation = apibuilder.config.helloworld.salutation;
    if (!params.username) {
        return cb(null, {
            error: 'Invalid name'
        });
    }
    const body = salutation + ' ' + params.username;
    cb(null, body);
}
exports = module.exports = invoke

 

Method

The default method for the Greet Codeblock flow-node is:

  • Greet - The codeblock to run with the greet flow.

Parameter

The Greet method parameter is:

Parameter Type Configuration selection

username

string Selector, String

Outputs

The Greet method outputs are:

Output Type Description Save output value as:

next

string The codeblock completed.

$.greeting

error

object The codeblock failed to complete.

$.error

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