[Codegen/Typespec] Handling Base64 sources

[HarshaNalluru]

Need to support NodeJS.ReadableStream | Blob | ArrayBuffer | ArrayBufferView in Typespec code generation for base64 sources

Document Intelligence

Typespec

@doc("Document analysis parameters.")
model AnalyzeDocumentRequest {
  @doc("Document URL to analyze.  Either urlSource or base64Source must be specified.")
  urlSource?: url;

  @doc("""
  Base64 encoding of the document to analyze.  Either urlSource or base64Source
  must be specified.
  """)
  base64Source?: bytes;
}

Source - https://github.com/Azure/azure-rest-api-specs/blob/eaf8b6f8e3ae429c8100471a9772a4bee9a5e472/specification/ai/DocumentIntelligence/models.tsp#L288C1-L298C2

Generated code

/** Document analysis parameters. */
export interface AnalyzeDocumentRequest {
  /** Document URL to analyze.  Either urlSource or base64Source must be specified. */
  urlSource?: string;
  /**
   * Base64 encoding of the document to analyze.  Either urlSource or base64Source
   * must be specified.
   */
  base64Source?: string;
}

User Sample

      const filePath = path.join(ASSET_PATH, "forms", "Invoice_1.pdf");
      const base64Source = fs.readFileSync(filePath, { encoding: "base64" });
      const initialResponse = await client
        .path("/documentModels/{modelId}:analyze", "prebuilt-layout")
        .post({
          contentType: "application/json",
          body: {
            base64Source,
          }
        });

Form Recognizer

In the older Form Recognizer library, we used to support..

/**
 * A request input that can be uploaded as binary data to the Form Recognizer service. Form Recognizer treats `string`
 * inputs as URLs, so to send a string as a _binary_ input, first convert the string to one of the following input
 * types.
 */
export type FormRecognizerRequestBody =
  | NodeJS.ReadableStream
  | Blob
  | ArrayBuffer
  | ArrayBufferView;

  public async beginAnalyzeDocument(
    modelId: string,
    document: FormRecognizerRequestBody,
    options?: AnalyzeDocumentOptions
  ): Promise<AnalysisPoller>;

  public async beginAnalyzeDocumentFromUrl(
    modelId: string,
    documentUrl: string,
    options?: AnalyzeDocumentOptions
  ): Promise<AnalysisPoller>;

User sample

        const filePath = path.join(ASSET_PATH, "forms", "Invoice_1.pdf");
        const stream = fs.createReadStream(filePath);
        const poller = await client.beginAnalyzeDocument(
          PrebuiltModels.Layout,
          stream,
          testPollingOptions
        );

Feature Request

The ask here is to support NodeJS.ReadableStream | Blob | ArrayBuffer | ArrayBufferView in Typespec code generation for base64 sources instead of asking users to provide base64 sources.