Merge pull request #454 from BSd3v/fix-infinite-no-rows

Author: BSd3v

CHANGELOG.md

@@ -13,6 +13,8 @@ Links "DE#nnn" prior to version 2.0 point to the Dash Enterprise closed-source D
   - Added test for `OBJ_MAYBE_FUNCTION_OR_MAP_MAYBE_FUNCTIONS` to test that the value is an object before parsing, 
   - this allows for reused keys to not comply with being an object
 
+### Fixed
+- [#454](https://github.com/plotly/dash-ag-grid/pull/454) fixes issue where a rowCount of 0 would cause the grid not to display new data
 
 ## [35.2.0] - 2026-04-03
 ### Added 

src/lib/fragments/AgGrid.react.js

@@ -274,6 +274,9 @@ export function DashAgGrid(props) {
     const [openGroups, setOpenGroups] = useState({});
     const [columnState_push, setColumnState_push] = useState(true);
     const [rowTransactionState, setRowTransactionState] = useState(null);
+    const resettingCount = useRef(false);
+    const prevRowCountRef = useRef(null);
+    const resetTimeoutRef = useRef(null);
 
     const components = useMemo(
         () => ({
@@ -841,9 +844,11 @@ export function DashAgGrid(props) {
         return {
             getRows(params) {
                 getRowsParams.current = params;
+                if (resettingCount.current) {
+                    return;
+                }
                 customSetProps({getRowsRequest: params});
             },
-
             destroy() {
                 getRowsParams.current = null;
             },
@@ -1408,13 +1413,50 @@ export function DashAgGrid(props) {
         }
     }, [props.id]);
 
-    // Handle infinite scrolling datasource
+    // handle getRowsResponse
     useEffect(() => {
-        if (isDatasourceLoadedForInfiniteScrolling()) {
+        if (isDatasourceLoadedForInfiniteScrolling() && getRowsParams.current) {
+            const params = getRowsParams.current;
+
             const {rowData, rowCount} = props.getRowsResponse;
-            getRowsParams.current.successCallback(rowData, rowCount);
+
+            // If we were previously at 0 rows, tell ag‑Grid the new count first,
+            // then defer the successCallback so ag‑Grid has processed setRowCount.
+            // This avoids an edge case where ag‑Grid ignores the successCallback because it thinks the
+            // request is already fulfilled, since the row count is >0, but then doesn't render any rows
+            // because it hasn't processed the new row count yet.
+            // We do not use purge, reset on the cache or datasource refresh here,
+            // since those would trigger a new getRows request, which we do not want since we already have the new data
+            // and just need to get ag‑Grid to process the new row count and render it.
+            if (
+                prevRowCountRef.current !== null &&
+                prevRowCountRef.current === 0
+            ) {
+                resettingCount.current = true;
+                params.api.setRowCount(rowCount, false);
+
+                resetTimeoutRef.current = setTimeout(() => {
+                    resettingCount.current = false;
+                    const p = getRowsParams.current;
+                    if (p) {
+                        p.successCallback(rowData, rowCount);
+                    }
+                }, 0);
+            } else {
+                params.successCallback(rowData, rowCount);
+            }
+
+            prevRowCountRef.current = rowCount;
             customSetProps({getRowsResponse: null});
         }
+
+        return () => {
+            if (resetTimeoutRef.current) {
+                clearTimeout(resetTimeoutRef.current);
+                resetTimeoutRef.current = null;
+            }
+            resettingCount.current = false;
+        };
     }, [props.getRowsResponse]);
 
     // Handle master detail response

tests/test_infinite_scroll.py

@@ -3,12 +3,12 @@
 """
 
 import dash_ag_grid as dag
-import dash
-from dash import Input, Output, html, dcc, Dash, no_update
-from . import utils
-import pandas as pd
+from dash import Input, Output, html, dcc, Dash, no_update, ctx
 from dash.testing.wait import until
+from . import utils
 import time
+import numpy as np
+import pandas as pd
 
 
 def test_is001_infinite_scroll(dash_duo):
@@ -247,4 +247,87 @@ def scroll(n):
     for x in range(8):
         dash_duo.find_element("#scroll").click()
         time.sleep(3)  # pausing to emulate separation because user inputs
-    assert list(filter(lambda i: i.get("level") != "WARNING", dash_duo.get_logs())) == []
+    assert list(filter(lambda i: i.get("level") != "WARNING", dash_duo.get_logs())) == []
+
+def test_is003_infinite_scroll_clear(dash_duo):
+    app = Dash(__name__)
+    data = pd.DataFrame(
+        {
+            "id": [str(x) for x in range(1000)],
+            "value": np.random.rand(1000),
+        }
+    )
+
+    clear_button = html.Button("Clear", id="clear")
+    reset_button = html.Button("Reset", id='reset')
+
+    grid = dag.AgGrid(
+        columnDefs=[
+            {"field": "id"},
+            {"field": "value"},
+        ],
+        getRowId="params.data.id",
+        rowModelType="infinite",
+        id="grid"
+    )
+
+    test_data = []
+
+
+    @app.callback(
+        Output(grid, "getRowsResponse"),
+        Input(grid, "getRowsRequest"),
+        Input(clear_button, "n_clicks"),
+        Input(reset_button, "n_clicks"),
+        prevent_initial_call=True,
+    )
+    def update_rfq_grid_rows(
+        request,
+        n_clicks_clear,
+        n_clicks_reset,
+    ):
+        if ctx.triggered_id == "clear":
+            response = {
+                "rowData": [], "rowCount": 0,
+            }
+            return response
+
+        if request is None:
+            partial_df = data.head(100)
+        else:
+            partial_df = data.iloc[request["startRow"] : request["endRow"]]
+
+        response = {
+            "rowData": partial_df.to_dict("records"),
+            "rowCount": len(data.index),
+        }
+        test_data.append('response')
+        return response
+
+    app.layout = html.Div(
+        children=[
+            clear_button,
+            reset_button,
+            grid,
+        ]
+    )
+
+    dash_duo.start_server(app)
+
+    grid_dom = utils.Grid(dash_duo, 'grid')
+    grid_dom.wait_for_cell_text(0, 0, "0")
+
+    for x in range(2, 5):
+        dash_duo.find_element("#clear").click()
+        until(
+            lambda: len(
+                dash_duo.find_elements(
+                    "#grid .ag-center-cols-container > *"
+                )
+            )
+                    == 0,
+            timeout=3,
+        )
+        dash_duo.find_element("#reset").click()
+        grid_dom.wait_for_cell_text(0, 0, "0")
+        assert x == len(test_data)  # make sure the callback was called the expected number of times