llm: consider null format same as empty value

README.md

@@ -407,8 +407,8 @@ See the [API documentation](./docs/api.md) for all endpoints.
 
 ### Database
 
-- [PostgreSQL extension pgai](https://github.com/timescale/pgai) (Create and search embeddings from Ollama models using pgvector)
-   - [Get started guide](https://github.com/timescale/pgai/blob/main/docs/ollama.md)
+- [pgai](https://github.com/timescale/pgai) - PostgreSQL as a vector database (Create and search embeddings from Ollama models using pgvector)
+   - [Get started guide](https://github.com/timescale/pgai/blob/main/docs/vectorizer-quick-start.md)
 - [MindsDB](https://github.com/mindsdb/mindsdb/blob/staging/mindsdb/integrations/handlers/ollama_handler/README.md) (Connects Ollama models with nearly 200 data platforms and apps)
 - [chromem-go](https://github.com/philippgille/chromem-go/blob/v0.5.0/embed_ollama.go) with [example](https://github.com/philippgille/chromem-go/tree/v0.5.0/examples/rag-wikipedia-ollama)
 - [Kangaroo](https://github.com/dbkangaroo/kangaroo) (AI-powered SQL client and admin tool for popular databases)

llm/server.go

@@ -701,7 +701,7 @@ func (s *llmServer) Completion(ctx context.Context, req CompletionRequest, fn fu
 
 	if len(req.Format) > 0 {
 		switch {
-		case bytes.Equal(req.Format, []byte(`""`)):
+		case bytes.Equal(req.Format, []byte(`""`)) || bytes.Equal(req.Format, []byte(`null`)):
 			// fallthrough
 		case bytes.Equal(req.Format, []byte(`"json"`)):
 			request["grammar"] = grammarJSON

llm/server_test.go

@@ -46,7 +46,7 @@ func TestLLMServerCompletionFormat(t *testing.T) {
 		}
 	}
 
-	valids := []string{`"json"`, `{"type":"object"}`, ``, `""`}
+	valids := []string{`"json"`, `{"type":"object"}`, ``, `""`, `null`}
 	for _, valid := range valids {
 		err := s.Completion(ctx, CompletionRequest{
 			Options: new(api.Options),