[Data Mapper] Enable Visualization for JSON Outputs

[madushajg]

Current Limitation

Currently, when a user opens a transformation function that returns a json type, the Data Mapper diagram fails to visualize the output structure and the corresponding mapping links.

function transformToJson(Input payload) returns json =>
    {
        id: payload.id,
        name: payload.customerName,
        email: payload.customerEmail
    };

Suggested Improvement

To enhance the usability and clarity of the Data Mapper for functions returning json, we can go for the following two improvements:

1. Enhanced Visualization of Fields and Mapping Links

The Data Mapper should attempt to infer and display the structure of the resulting JSON object based on the transformation function's body.

2. Provide Guidance for Improved Type Definition

Since the structure of the json type is dynamic and cannot always be fully inferred at design time, the Data Mapper should encourage users to define a concrete type for better tooling support.

Version

BI v1.5.3 | Ballerina v5.6.3

[pasindufernando1]

Put on hold due to the need of discussions

[pasindufernando1]

During the offline discussions made on 09/12/2025 with @gimantha , @KavinduZoysa it was decided to proceed with the option 1 suggested by @madushajg. The back end will be improved to infer the type structure based on the actual code.

[pasindufernando1]

During the offline discussion made on 10/12/2025 with @gimantha , @KavinduZoysa it was decided to create the mappings model to visualize json only for the basic scenarios which the case is either

1. Having a mapping constructor (keys and fields)
2. The case of transformation functions where the output type is a json