Update app.py

app.py

@@ -1720,18 +1720,30 @@ with gr.Blocks(css=css, title="DataSynth — Analytics Hub") as demo:
         outputs=[prep_output, clean_state]
     )
 
-    # Column selection helpers
-    def _select_all_cols(df_path):
-        if not df_path:
-            return gr.CheckboxGroup.update(choices=[])
-        df = pd.read_csv(df_path)
-        return gr.CheckboxGroup.update(value=df.columns.tolist())
+    # safe helper: read columns from persisted df path
+    def _cols_from_df_path(df_path):
+        try:
+            if not df_path:
+                return []
+            df = pd.read_csv(df_path)
+            return [str(c) for c in df.columns]
+        except Exception:
+            return []
+
+    # callback for Select All button
+    def select_all_cols(df_path):
+        cols = _cols_from_df_path(df_path)
+        # return gr.update(...) (NOT component.update). Set both choices and value.
+        return gr.update(choices=cols, value=cols)
 
-    def _deselect_all_cols():
-        return gr.CheckboxGroup.update(value=[])
+    # callback for Deselect All button
+    def deselect_all_cols(df_path):
+        cols = _cols_from_df_path(df_path)
+        # keep choices, but clear value to deselect all
+        return gr.update(choices=cols, value=[])
 
-    select_all_cols.click(fn=_select_all_cols, inputs=[df_state], outputs=[available_cols])
-    deselect_all_cols.click(fn=_deselect_all_cols, outputs=[available_cols])
+    select_all_cols.click(fn=select_all_cols, inputs=[df_state], outputs=[available_cols])
+    deselect_all_cols.click(fn=deselect_all_cols, inputs=[df_state], outputs=[available_cols])
 
     # Show/hide custom value inputs based on method selection
     def _toggle_custom_inputs(num_method, cat_method):