From b0bdd4e45d6de4a8f60cffe8d82f063381088f6c Mon Sep 17 00:00:00 2001
From: Spencer Ahrens <sahrens@fb.com>
Date: Mon, 5 Oct 2015 13:42:25 -0700
Subject: [PATCH] Fix ListView bug where onEndReached wouldn't trigger
 initially
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Summary: @​public

Sometimes we want to load a very small number of rows initially and want the
onEndReached callback to be called immediately to trigger more data to be
loaded without waiting for the  user to scroll at all.  This diff makes that
happen by also checking on mount instead of only when scrolling.

Reviewed By: @vjeux

Differential Revision: D2507184

fb-gh-sync-id: ea8e47667d00387a935a426dd45afe978fd6d8cd
---
 .../CustomComponents/ListView/ListView.js     | 22 ++++++++++++-------
 1 file changed, 14 insertions(+), 8 deletions(-)

diff --git a/Libraries/CustomComponents/ListView/ListView.js b/Libraries/CustomComponents/ListView/ListView.js
index 4554eb681..834de83a0 100644
--- a/Libraries/CustomComponents/ListView/ListView.js
+++ b/Libraries/CustomComponents/ListView/ListView.js
@@ -452,10 +452,23 @@ var ListView = React.createClass({
     this._updateVisibleRows(childFrames);
   },
 
+  _maybeCallOnEndReached: function(event) {
+    if (this.props.onEndReached &&
+        this.scrollProperties.contentLength !== this._sentEndForContentLength &&
+        this._getDistanceFromEnd(this.scrollProperties) < this.props.onEndReachedThreshold &&
+        this.state.curRenderedRowsCount === this.props.dataSource.getRowCount()) {
+      this._sentEndForContentLength = this.scrollProperties.contentLength;
+      this.props.onEndReached(event);
+      return true;
+    }
+    return false;
+  },
+
   _renderMoreRowsIfNeeded: function() {
     if (this.scrollProperties.contentLength === null ||
       this.scrollProperties.visibleLength === null ||
       this.state.curRenderedRowsCount === this.props.dataSource.getRowCount()) {
+      this._maybeCallOnEndReached();
       return;
     }
 
@@ -570,14 +583,7 @@ var ListView = React.createClass({
       isVertical ? 'y' : 'x'
     ];
     this._updateVisibleRows(e.nativeEvent.updatedChildFrames);
-    var nearEnd = this._getDistanceFromEnd(this.scrollProperties) < this.props.onEndReachedThreshold;
-    if (nearEnd &&
-        this.props.onEndReached &&
-        this.scrollProperties.contentLength !== this._sentEndForContentLength &&
-        this.state.curRenderedRowsCount === this.props.dataSource.getRowCount()) {
-      this._sentEndForContentLength = this.scrollProperties.contentLength;
-      this.props.onEndReached(e);
-    } else {
+    if (!this._maybeCallOnEndReached(e)) {
       this._renderMoreRowsIfNeeded();
     }