Handle JSON payloads as strings in HTTP Connectors task

In this tutorial, you learn how to handle JSON payloads when you use an HTTP Connectors task in Application Integration.

Incorrectly treating the payload can cause APIs to misinterpret it, resulting in 400 Bad Request errors. To ensure APIs receive and parse your JSON payload correctly, treat the JSON payload as a string and explicitly set the Content-Type header to application/json.

Before you begin

• Verify you can access Application Integration.

• Select your Google Cloud project and complete the following tasks:

  • Grant the following roles to the service account that you want to use to create the connection:
    • roles/secretmanager.viewer
    • roles/secretmanager.secretAccessor
  • Enable the following services:
    • secretmanager.googleapis.com (Secret Manager API)
    • connectors.googleapis.com (Connectors API)

    If you haven't enabled these services for your project, the Create Connection page prompts you to enable them when you create the connection.

• Add and configure an HTTP Connectors task.
• Add and configure the Data Transformer task to prepare the JSON payload and headers.

Handle JSON payloads as strings

To handle JSON payloads that contain special characters when you use an HTTP Connectors task, complete the following steps:

• Create a string variable for the JSON payload
• Map the string variable to the connector input body
• Add a custom Content-Type header
• Execute the HTTP Connectors task

Create a string variable for the JSON payload

1. In the Google Cloud console, go to the Application Integration page.

   Go to Application Integration

2. In the navigation menu, click Integrations.
3. Select an existing integration or create a new one. Ensure your integration includes the configured HTTP Connectors and Data Transformer tasks as detailed in the Before you begin section.
4. In the integration editor, click add Create to open the Create variable dialog.
5. In the Create variable dialog:
   1. Enter the following information:
      1. Name: Enter a name, for example, jsonPayloadString.
      2. Data Type: Select String.
      3. Default Value:
         • If the JSON payload is populated by a preceding task in the integration flow, for example, another Data Transformer task, leave this field empty. The variable will be populated dynamically based on the output of previous tasks in the integration.
         • If the JSON payload is not populated by a preceding task, you must provide a static default JSON payload. Enter the JSON structure as a single string in this field.

           Here are two examples of how to enter JSON strings in the Default Value field:

           Without special characters: To represent the JSON {"name": "Developer", "key": "test"}, enter exactly: { "name": "Developer", "key": "test" }.

           With special characters: When your JSON contains special characters like newline (\n), you must escape them. For example, to represent the JSON {"key": "value1\nvalue2"}, enter {"key": "value1\\nvalue2"} in the field.

   2. Click Create.
   Create a string variable for the JSON payload
For more information on creating and using variables, see Variables.

Map the string variable to the connector input body

In the Data Transformer Editor, map the jsonPayloadString variable to the connectorInputPayload.Body field.

1. In your integration, add a Data Transformer task.
2. Open the Data Transformer Editor. You can use either the Diagram mode or the Script mode.
3. To map the variable:
   • Diagram mode: Add jsonPayloadString as an input and map it to the connectorInputPayload.Body output field.
   • Script mode: Write Jsonnet code to assign the value: connectorInputPayload.Body = vars.jsonPayloadString;.

Add a custom Content-Type header

1. In the Data Transformer Editor, add a mapping for custom headers to the connectorInputPayload.Headers field.
   • Diagram mode: Add a constant input with the value {"Content-Type": "application/json"} and map it to connectorInputPayload.Headers.
   • Script mode: Add the following Jsonnet to set the header:

     connectorInputPayload.Headers = {
      "Content-Type": "application/json"
     };
      

Execute the HTTP Connectors task

Before executing your integration, verify that connectorInputPayload.Body is populated by the jsonPayloadString variable and that connectorInputPayload.Headers includes the Content-Type: application/json header. This setup ensures the HTTP Connectors task sends the JSON payload as a string with the correct Content-Type in the Data Transformer task.

Run your integration to test the API request. If the API returns a 400 Bad Request error, verify the mappings for connectorInputPayload.Body and connectorInputPayload.Headers again in the Data Transformer task.

What's next

Try building integrations with other connectors. For a list of all supported connectors, see Connector reference.