---
created: 2026-05-08
status: approved
---

# Cascading Channel-Model Selector for User Ratio

## Goal

Improve the "Add Ratio" modal in UserRatioSection: select channel first, then pick a model from that channel's supported models via dropdown instead of manual text input.

## Scope

Single file: `web/src/components/table/users/modals/UserRatioSection.jsx`

No backend changes — the existing `/api/channel/` endpoint already returns the `models` field (comma-separated string) for each channel.

## Design

### Data flow

1. `loadChannels()` fetches channel list, stores two things:
   - `channelOptions`: `[{ label, value }]` for the channel dropdown (existing)
   - `channelMap`: `{ [channelId]: channelObject }` for looking up `models` by channel ID (new)
2. When user selects a channel in the form:
   - Parse `channel.models` by comma into an array
   - Set `modelOptions` to `[{ label: model, value: model }]` for each model
   - Clear any previously selected model value
3. Model dropdown uses `modelOptions` with `filter` and `showClear`, disabled when no channel is selected

### Form field order

1. Channel (Select, with search) — existing
2. Model (Select, with search) — changed from Input to Select
3. Ratio (InputNumber) — existing

### What does NOT change

- Backend API and data model
- Table columns and display
- Submit payload format (`model_name`, `channel_id`, `ratio`)