fix: show tips for non exist ollama model

--bug=1050792 --user=刘瑞斌 【模型管理】ollama图片理解模型，选择服务器上不存在的模型时没有自动下载 https://www.tapd.cn/57709429/s/1636732

apps/setting/models_provider/impl/ollama_model_provider/credential/image.py

@@ -37,25 +37,15 @@ def is_valid(self, model_type: str, model_name, model_credential: Dict[str, obje
         model_type_list = provider.get_model_type_list()
         if not any(list(filter(lambda mt: mt.get('value') == model_type, model_type_list))):
             raise AppApiException(ValidCode.valid_error.value, f'{model_type} 模型类型不支持')
-
-        for key in ['api_base', 'api_key']:
-            if key not in model_credential:
-                if raise_exception:
-                    raise AppApiException(ValidCode.valid_error.value, f'{key} 字段为必填字段')
-                else:
-                    return False
         try:
-            model = provider.get_model(model_type, model_name, model_credential)
-            res = model.stream([HumanMessage(content=[{"type": "text", "text": "你好"}])])
-            for chunk in res:
-                print(chunk)
+            model_list = provider.get_base_model_list(model_credential.get('api_base'))
         except Exception as e:
-            if isinstance(e, AppApiException):
-                raise e
-            if raise_exception:
-                raise AppApiException(ValidCode.valid_error.value, f'校验失败,请检查参数是否正确: {str(e)}')
-            else:
-                return False
+            raise AppApiException(ValidCode.valid_error.value, "API 域名无效")
+        exist = [model for model in (model_list.get('models') if model_list.get('models') is not None else []) if
+                 model.get('model') == model_name or model.get('model').replace(":latest", "") == model_name]
+        if len(exist) == 0:
+            raise AppApiException(ValidCode.model_not_fount, "模型不存在,请先下载模型")
+
         return True
 
     def encryption_dict(self, model: Dict[str, object]):