Refactor search engine

* move text query build logic to a method
* Rename `TextFieldQuery` to `TextQuery`

src/argilla/server/search_engine.py

@@ -64,14 +64,14 @@ class Config:
 
 
 @dataclasses.dataclass
-class TextFieldQuery:
+class TextQuery:
     q: str
     field: Optional[str] = None
 
 
 @dataclasses.dataclass
 class Query:
-    text: TextFieldQuery
+    text: TextQuery
 
 
 @dataclasses.dataclass
@@ -108,7 +108,7 @@ async def create_index(self, dataset: Dataset):
             fields[f"fields.{field.name}"] = self._es_mapping_for_field(field)
 
         # See https://www.elastic.co/guide/en/elasticsearch/reference/current/dynamic-templates.html
-        dynamic_templates = [
+        dynamic_templates: List[dict] = [
             {
                 f"{question.name}_responses": {
                     "path_match": f"responses.*.values.{question.name}",
@@ -161,31 +161,11 @@ async def search(
         # See https://www.elastic.co/guide/en/elasticsearch/reference/current/search-search.html
 
         if isinstance(query, str):
-            query = Query(text=TextFieldQuery(q=query))
+            query = Query(text=TextQuery(q=query))
 
-        bool_query = {"must": []}
-        if not query.text.field:
-            # https://www.elastic.co/guide/en/elasticsearch/reference/current/query-dsl-combined-fields-query.html
-            text_query = {
-                "combined_fields": {
-                    "query": query.text.q,
-                    "fields": [f"fields.{field.name}" for field in dataset.fields],
-                    "operator": "and",
-                }
-            }
-        else:
-            # See https://www.elastic.co/guide/en/elasticsearch/reference/current/query-dsl-match-query.html
-            text_query = {
-                "match_phrase": {
-                    f"fields.{query.text.field}": {
-                        "query": query.text.q,
-                        "operator": "and",
-                    }
-                }
-            }
-
-        bool_query["must"].append(text_query)
+        text_query = self._text_query_builder(dataset, text=query.text)
 
+        bool_query = {"must": [text_query]}
         if user_response_status_filter:
             # See https://www.elastic.co/guide/en/elasticsearch/reference/current/query-dsl-terms-query.html
             user_response_status_field = f"responses.{user_response_status_filter.user.username}.status"
@@ -213,6 +193,18 @@ async def search(
 
         return SearchResponses(items=items)
 
+    @staticmethod
+    def _text_query_builder(dataset: Dataset, text: TextQuery) -> dict:
+        if not text.field:
+            # https://www.elastic.co/guide/en/elasticsearch/reference/current/query-dsl-combined-fields-query.html
+            field_names = [
+                f"fields.{field.name}" for field in dataset.fields if field.settings.get("type") == FieldType.text
+            ]
+            return {"combined_fields": {"query": text.q, "fields": field_names, "operator": "and"}}
+        else:
+            # See https://www.elastic.co/guide/en/elasticsearch/reference/current/query-dsl-match-query.html
+            return {"match": {f"fields.{text.field}": {"query": text.q, "operator": "and"}}}
+
     def _field_mapping_for_question(self, question: Question):
         settings = question.parsed_settings