Add HTTP language support

[koros]

Add HTTP as a supported language for snippet generation.

Task List

• Adapt the generated RequestBuilder class to produce .http snippet files.
• Exclude unnecessary generated code not used by HTTP snippets, such as Models and Utility classes.
• Serialize models into JSON to populate the RequestBody object for POST operations, handling edge cases like inheritance and union classes.
• Generate a settings.json file — brainstorm to define its content and determine the source of this information.

[koros]

Overview

This project builds upon the existing logic, which generates a request builder for each path segment. The goal is to enhance the current structure by making a few modifications to generate:

• URL Templates for each path
• Supported HTTP operations (GET, POST, PATCH, etc.)
• A Request Body placeholder, for example:

  Content-Type: application/json
  
  {
    "userId": 0,
    "id": 0,
    "title": "string",
    "body": "string"
  }

Approach

To achieve this, follow these steps:

1. Identify RequestBuilder Classes

   • Select all classes of type CodeClassKind.RequestBuilder.

2. Extract URL Templates and HTTP Operations

   • From each class's InnerChildElements property:
     • Extract the URLTemplate by selecting the CodeProperty of type CodePropertyKind.UrlTemplate.
     • Extract supported HTTP operations by selecting all Kiota.Builder.CodeDOM.CodeElement elements of type CodeMethod whose kind is CodeMethodKind.RequestExecutor.

3. Map HTTP Methods and Request Body

The following table summarizes how to map each method:

Property	Mapping
Name	Maps to HTTP operation in the snippet file (e.g., GET, POST, PATCH)
RequestBody	If a parameter of kind CodeParameterKind.RequestBody exists, map it to the request body

4. Generate Request Body Placeholders
   • If the request body parameter is present, construct the placeholder JSON by selecting all properties of kind CodePropertyKind.Custom from the Type.TypeDefinition of the parameter.

The following table explains how to map each property in the request body:

Property	Mapping
Name	Maps to the field name (e.g., postTitle)
Type.Name	Maps to the field type (e.g., string, number, boolean)

5. Extract Query Parameters
   To extract query parameters, follow these steps:

   • Select all classes of kind CodeClassKind.QueryParameters. These classes contain information about the query parameters for each request.
   • From each class's InnerChildElements property, select all properties of kind CodePropertyKind.QueryParameter.

   Once you've accessed these properties, use the following mapping to handle query parameters:

   Property	Mapping
   Name	Maps to the query parameter name (e.g., userId, filter)

   Additionally, to extract path parameters from the request URL (if present), select the properties of kind CodePropertyKind.PathParameters.

[calebkiage]

This is a great start, could you add information about the mapping between parameters and http snippet variables? I think we also wanted to map descriptions

[koros]

I'm unsure whether we will be using variables. @darrelmiller, could you please confirm? From our call, I recall you mentioning that we should remove the double curly braces, which suggests users will input the actual values directly. Based on that, my understanding is that the URLs will resemble what's in the documentation, such as:

GET https://graph.microsoft.com/v1.0/directory/deletedItems/{object-id}

[maisarissi]

I have added a comment here: #5543 (comment) that I believe we should take into consideration when http is the language.

[sebastienlevert]

We need variables when required. Else, we only use a comment that "hints" the URI template so devs can play around. Please refer to #5543. Also adding @baywet to this thread for validation of the design.

[petrhollayms]

@calebkiage is working with Koros now, so looking forward for his review first :-)

[calebkiage]

My remarks:

1. Will a single request builder map to 1 http file? I assume yes? If not, maybe we should add a mapping of the file and folder structure as well?
2. In the table defined in section 3. Map HTTP Methods and Request Body, where will you get the Name value from? I'm assuming the CodeMethod?
3. Is there a way to make it easier for consumers of the snippets to set the values of the body? Imagine if we have many fields in the object. This may be post-mvp. cc: @maisarissi