Feat: Support passing knowledge base id as variable in retrieval component (#7088)

### What problem does this PR solve?

Fix #6600

Hello, I have the same business requirement as #6600. My use case is: 

We have many departments (> 20 now and increasing), and each department
has its own knowledge base. Because the agent workflow is the same, so I
want to change the knowledge base on the fly, instead of creating agents
for every department.

It now looks like this:


![屏幕截图_20250416_212622](https://github.com/user-attachments/assets/5cb3dade-d4fb-4591-ade3-4b9c54387911)

Knowledge bases can be selected from the dropdown, and passed through
the variables in the table. All selected knowledge bases are used for
retrieval.

### Type of change

- [ ] Bug Fix (non-breaking change which fixes an issue)
- [x] New Feature (non-breaking change which adds functionality)
- [ ] Documentation Update
- [ ] Refactoring
- [ ] Performance Improvement
- [ ] Other (please describe):

agent/component/base.py

 import os
 import logging
 from functools import partial
-from typing import Tuple, Union
+from typing import Any, Tuple, Union
 
 import pandas as pd
 
     def set_output(self, v):
         setattr(self._param, self._param.output_var_name, v)
 
+    def _fetch_outputs_from(self, sources: list[dict[str, Any]]) -> list[pd.DataFrame]:
+        outs = []
+        for q in sources:
+            if q.get("component_id"):
+                if q["component_id"].split("@")[0].lower().find("begin") >= 0:
+                    cpn_id, key = q["component_id"].split("@")
+                    for p in self._canvas.get_component(cpn_id)["obj"]._param.query:
+                        if p["key"] == key:
+                            outs.append(pd.DataFrame([{"content": p.get("value", "")}]))
+                            break
+                    else:
+                        assert False, f"Can't find parameter '{key}' for {cpn_id}"
+                    continue
+
+                if q["component_id"].lower().find("answer") == 0:
+                    txt = []
+                    for r, c in self._canvas.history[::-1][:self._param.message_history_window_size][::-1]:
+                        txt.append(f"{r.upper()}:{c}")
+                    txt = "\n".join(txt)
+                    outs.append(pd.DataFrame([{"content": txt}]))
+                    continue
+
+                outs.append(self._canvas.get_component(q["component_id"])["obj"].output(allow_partial=False)[1])
+            elif q.get("value"):
+                outs.append(pd.DataFrame([{"content": q["value"]}]))
+        return outs
+
     def get_input(self):
         if self._param.debug_inputs:
             return pd.DataFrame([{"content": v["value"]} for v in self._param.debug_inputs if v.get("value")])
 
         if self._param.query:
             self._param.inputs = []
-            outs = []
-            for q in self._param.query:
-                if q.get("component_id"):
-                    if q["component_id"].split("@")[0].lower().find("begin") >= 0:
-                        cpn_id, key = q["component_id"].split("@")
-                        for p in self._canvas.get_component(cpn_id)["obj"]._param.query:
-                            if p["key"] == key:
-                                outs.append(pd.DataFrame([{"content": p.get("value", "")}]))
-                                self._param.inputs.append({"component_id": q["component_id"],
-                                                           "content": p.get("value", "")})
-                                break
-                        else:
-                            assert False, f"Can't find parameter '{key}' for {cpn_id}"
-                        continue
-
-                    if q["component_id"].lower().find("answer") == 0:
-                        txt = []
-                        for r, c in self._canvas.history[::-1][:self._param.message_history_window_size][::-1]:
-                            txt.append(f"{r.upper()}:{c}")
-                        txt = "\n".join(txt)
-                        self._param.inputs.append({"content": txt, "component_id": q["component_id"]})
-                        outs.append(pd.DataFrame([{"content": txt}]))
-                        continue
-
-                    outs.append(self._canvas.get_component(q["component_id"])["obj"].output(allow_partial=False)[1])
-                    self._param.inputs.append({"component_id": q["component_id"],
-                                               "content": "\n".join(
-                                                   [str(d["content"]) for d in outs[-1].to_dict('records')])})
-                elif q.get("value"):
-                    self._param.inputs.append({"component_id": None, "content": q["value"]})
-                    outs.append(pd.DataFrame([{"content": q["value"]}]))
+            outs = self._fetch_outputs_from(self._param.query)
+
+            for out in outs:
+                records = out.to_dict("records")
+                content: str
+
+                if len(records) > 1:
+                    content = "\n".join(
+                        [str(d["content"]) for d in records]
+                    )
+                else:
+                    content = records[0]["content"]
+
+                self._param.inputs.append({
+                    "component_id": records[0].get("component_id"),
+                    "content": content
+                })
+
             if outs:
                 df = pd.concat(outs, ignore_index=True)
                 if "content" in df:

agent/component/retrieval.py

         self.top_n = 8
         self.top_k = 1024
         self.kb_ids = []
+        self.kb_vars = []
         self.rerank_id = ""
         self.empty_response = ""
         self.tavily_api_key = ""
     def _run(self, history, **kwargs):
         query = self.get_input()
         query = str(query["content"][0]) if "content" in query else ""
-        kbs = KnowledgebaseService.get_by_ids(self._param.kb_ids)
+
+        kb_ids: list[str] = self._param.kb_ids or []
+
+        kb_vars = self._fetch_outputs_from(self._param.kb_vars)
+
+        if len(kb_vars) > 0:
+            for kb_var in kb_vars:
+                if len(kb_var) == 1:
+                    kb_ids.append(str(kb_var["content"][0]))
+                else:
+                    for v in kb_var.to_dict("records"):
+                        kb_ids.append(v["content"])
+
+        filtered_kb_ids: list[str] = [kb_id for kb_id in kb_ids if kb_id]
+
+        kbs = KnowledgebaseService.get_by_ids(filtered_kb_ids)
         if not kbs:
             return Retrieval.be_output("")
 
             rerank_mdl = LLMBundle(kbs[0].tenant_id, LLMType.RERANK, self._param.rerank_id)
 
         if kbs:
-            kbinfos = settings.retrievaler.retrieval(query, embd_mdl, kbs[0].tenant_id, self._param.kb_ids,
+            kbinfos = settings.retrievaler.retrieval(query, embd_mdl, kbs[0].tenant_id, filtered_kb_ids,
                                         1, self._param.top_n,
                                         self._param.similarity_threshold, 1 - self._param.keywords_similarity_weight,
                                         aggs=False, rerank_mdl=rerank_mdl,
         if self._param.use_kg and kbs:
             ck = settings.kg_retrievaler.retrieval(query,
                                                    [kbs[0].tenant_id],
-                                                   self._param.kb_ids,
+                                                   filtered_kb_ids,
                                                    embd_mdl,
                                                    LLMBundle(kbs[0].tenant_id, LLMType.CHAT))
             if ck["content_with_weight"]:

web/src/components/knowledge-base-item.tsx

 import { MultiSelect } from './ui/multi-select';
 
 interface KnowledgeBaseItemProps {
+  tooltipText?: string;
   required?: boolean;
   onChange?(): void;
 }
 
 const KnowledgeBaseItem = ({
+  tooltipText,
   required = true,
   onChange,
 }: KnowledgeBaseItemProps) => {
     <Form.Item
       label={t('knowledgeBases')}
       name="kb_ids"
-      tooltip={t('knowledgeBasesTip')}
+      tooltip={tooltipText || t('knowledgeBasesTip')}
       rules={[
         {
           required,

web/src/locales/en.ts

       promptTip:
         'Use the system prompt to describe the task for the LLM, specify how it should respond, and outline other miscellaneous requirements. The system prompt is often used in conjunction with keys (variables), which serve as various data inputs for the LLM. Use a forward slash `/` or the (x) button to show the keys to use.',
       promptMessage: 'Prompt is required',
+      knowledgeBasesTip:
+        'Select the knowledge bases to associate with this chat assistant, or choose variables containing knowledge base IDs below.',
+      knowledgeBaseVars: 'Knowledge base variables',
     },
   },
 };

web/src/locales/zh.ts

       promptMessage: '提示词是必填项',
       promptTip:
         '系统提示为大模型提供任务描述、规定回复方式，以及设置其他各种要求。系统提示通常与 key （变量）合用，通过变量设置大模型的输入数据。你可以通过斜杠或者 (x) 按钮显示可用的 key。',
+      knowledgeBasesTip: '选择关联的知识库，或者在下方选择包含知识库ID的变量。',
+      knowledgeBaseVars: '知识库变量',
     },
     footer: {
       profile: 'All rights reserved @ React',

web/src/pages/flow/form/components/dynamic-input-variable.tsx

 import styles from './index.less';
 
 interface IProps {
+  name?: string;
   node?: RAGFlowNodeType;
+  title?: string;
 }
 
 enum VariableType {
 const getVariableName = (type: string) =>
   type === VariableType.Reference ? 'component_id' : 'value';
 
-const DynamicVariableForm = ({ node }: IProps) => {
+const DynamicVariableForm = ({ name: formName, node }: IProps) => {
+  formName = formName || 'query';
   const { t } = useTranslation();
   const valueOptions = useBuildComponentIdSelectOptions(
     node?.id,
   const handleTypeChange = useCallback(
     (name: number) => () => {
       setTimeout(() => {
-        form.setFieldValue(['query', name, 'component_id'], undefined);
-        form.setFieldValue(['query', name, 'value'], undefined);
+        form.setFieldValue([formName, name, 'component_id'], undefined);
+        form.setFieldValue([formName, name, 'value'], undefined);
       }, 0);
     },
     [form],
   );
 
   return (
-    <Form.List name="query">
+    <Form.List name={formName}>
       {(fields, { add, remove }) => (
         <>
           {fields.map(({ key, name, ...restField }) => (
               </Form.Item>
               <Form.Item noStyle dependencies={[name, 'type']}>
                 {({ getFieldValue }) => {
-                  const type = getFieldValue(['query', name, 'type']);
+                  const type = getFieldValue([formName, name, 'type']);
                   return (
                     <Form.Item
                       {...restField}
   );
 }
 
-const DynamicInputVariable = ({ node }: IProps) => {
+const DynamicInputVariable = ({ name, node, title }: IProps) => {
   const { t } = useTranslation();
   return (
-    <FormCollapse title={t('flow.input')}>
-      <DynamicVariableForm node={node}></DynamicVariableForm>
+    <FormCollapse title={title || t('flow.input')}>
+      <DynamicVariableForm name={name} node={node}></DynamicVariableForm>
     </FormCollapse>
   );
 };

web/src/pages/flow/form/retrieval-form/index.tsx

       <Rerank></Rerank>
       <TavilyItem name={'tavily_api_key'}></TavilyItem>
       <UseKnowledgeGraphItem filedName={'use_kg'}></UseKnowledgeGraphItem>
-      <KnowledgeBaseItem></KnowledgeBaseItem>
+      <KnowledgeBaseItem
+        tooltipText={t('knowledgeBasesTip')}
+      ></KnowledgeBaseItem>
+      <DynamicInputVariable
+        name={'kb_vars'}
+        node={node}
+        title={t('knowledgeBaseVars')}
+      ></DynamicInputVariable>
       <Form.Item
         name={'empty_response'}
         label={t('emptyResponse', { keyPrefix: 'chat' })}