AgentFlow: Support multipart/form-data (file + fields) in Prediction API and map fields into $vars

[lokii2024]

Summary

When using AgentFlows (self-hosted Flowise), I need to send a file upload along with extra input values (e.g., process_id, project_id, project_type). Right now, the Prediction API only works with JSON (uploads[] + variables). If a client can only send multipart/form-data, the flow cannot consume both file and fields without writing a custom variables.

Howt to pass this custom variables and custom or this custom variable

[HenryHengZJ]

We have plan to allow File Upload as form input on the Start node, that way you can kick start the flow with other form input values with the files as well