Chat Use CVmodel (infiniflow#1607)

### What problem does this PR solve?

infiniflow#1230 

### Type of change

- [x] New Feature (non-breaking change which adds functionality)

api/db/services/dialog_service.py

@@ -13,6 +13,8 @@
 #  See the License for the specific language governing permissions and
 #  limitations under the License.
 #
+import os
+import json
 import re
 from copy import deepcopy
 
@@ -26,6 +28,7 @@
 from rag.nlp import keyword_extraction
 from rag.nlp.search import index_name
 from rag.utils import rmSpace, num_tokens_from_string, encoder
+from api.utils.file_utils import get_project_base_directory
 
 
 class DialogService(CommonService):
@@ -73,6 +76,15 @@ def count():
     return max_length, msg
 
 
+def llm_id2llm_type(llm_id):
+    fnm = os.path.join(get_project_base_directory(), "conf")
+    llm_factories = json.load(open(os.path.join(fnm, "llm_factories.json"), "r"))
+    for llm_factory in llm_factories["factory_llm_infos"]:
+        for llm in llm_factory["llm"]:
+            if llm_id == llm["llm_name"]:
+                return llm["model_type"].strip(",")[-1]
+
+
 def chat(dialog, messages, stream=True, **kwargs):
     assert messages[-1]["role"] == "user", "The last content of this conversation is not from user."
     llm = LLMService.query(llm_name=dialog.llm_id)
@@ -91,7 +103,10 @@ def chat(dialog, messages, stream=True, **kwargs):
 
     questions = [m["content"] for m in messages if m["role"] == "user"]
     embd_mdl = LLMBundle(dialog.tenant_id, LLMType.EMBEDDING, embd_nms[0])
-    chat_mdl = LLMBundle(dialog.tenant_id, LLMType.CHAT, dialog.llm_id)
+    if llm_id2llm_type(dialog.llm_id) == "image2text":
+        chat_mdl = LLMBundle(dialog.tenant_id, LLMType.IMAGE2TEXT, dialog.llm_id)
+    else:
+        chat_mdl = LLMBundle(dialog.tenant_id, LLMType.CHAT, dialog.llm_id)
 
     prompt_config = dialog.prompt_config
     field_map = KnowledgebaseService.get_field_map(dialog.kb_ids)
@@ -328,7 +343,10 @@ def get_table():
 
 
 def relevant(tenant_id, llm_id, question, contents: list):
-    chat_mdl = LLMBundle(tenant_id, LLMType.CHAT, llm_id)
+    if llm_id2llm_type(llm_id) == "image2text":
+        chat_mdl = LLMBundle(tenant_id, LLMType.IMAGE2TEXT, llm_id)
+    else:
+        chat_mdl = LLMBundle(tenant_id, LLMType.CHAT, llm_id)
     prompt = """
         You are a grader assessing relevance of a retrieved document to a user question. 
         It does not need to be a stringent test. The goal is to filter out erroneous retrievals.
@@ -347,7 +365,10 @@ def relevant(tenant_id, llm_id, question, contents: list):
 
 
 def rewrite(tenant_id, llm_id, question):
-    chat_mdl = LLMBundle(tenant_id, LLMType.CHAT, llm_id)
+    if llm_id2llm_type(llm_id) == "image2text":
+        chat_mdl = LLMBundle(tenant_id, LLMType.IMAGE2TEXT, llm_id)
+    else:
+        chat_mdl = LLMBundle(tenant_id, LLMType.CHAT, llm_id)
     prompt = """
         You are an expert at query expansion to generate a paraphrasing of a question.
         I can't retrieval relevant information from the knowledge base by using user's question directly.     

api/db/services/llm_service.py

@@ -70,7 +70,7 @@ def model_instance(cls, tenant_id, llm_type,
         elif llm_type == LLMType.SPEECH2TEXT.value:
             mdlnm = tenant.asr_id
         elif llm_type == LLMType.IMAGE2TEXT.value:
-            mdlnm = tenant.img2txt_id
+            mdlnm = tenant.img2txt_id if not llm_name else llm_name
         elif llm_type == LLMType.CHAT.value:
             mdlnm = tenant.llm_id if not llm_name else llm_name
         elif llm_type == LLMType.RERANK: