Fix AIField generation for mistral API provider (baserow#4996)

Author: dimmur-brw

backend/src/baserow/core/generative_ai/generative_ai_model_types.py

@@ -319,9 +319,7 @@ def prompt(
                 # accepts 1.
                 kwargs["temperature"] = min(temperature, 1)
             response = client.chat.complete(
-                messages=[
-                    {"role": "user", "content": [{"type": "text", "text": prompt}]}
-                ],
+                messages=[{"role": "user", "content": prompt}],
                 model=model,
                 **kwargs,
             )

changelog/entries/unreleased/bug/4994_fix_aifield_generation_for_mistral_api_provider.json

@@ -0,0 +1,9 @@
+{
+    "type": "bug",
+    "message": "Fix AIField generation for mistral API provider",
+    "issue_origin": "github",
+    "issue_number": 4994,
+    "domain": "database",
+    "bullet_points": [],
+    "created_at": "2026-03-17"
+}

premium/backend/src/baserow_premium/fields/job_types.py

@@ -512,7 +512,13 @@ def _generate_value_for(self, row: GeneratedTableModel) -> Any:
         # additional prompt trying to force the output, for example.
         message = ai_output_type.format_prompt(message, ai_field)
 
+        if not message or not message.strip():
+            # If the resolved prompt is empty, preserve the existing value instead
+            # of overwriting it with NULL in the database.
+            return getattr(row, ai_field.db_column, None)
+
         if self.use_file_fields:
+            file_ids = []
             try:
                 file_ids = AIFileManager.upload_files_from_file_field(
                     ai_field, row, generative_ai_model_type