OAPIF get feature count from server without fetching all features

qgis · Jan 31, 2023 · aa729bc · aa729bc
1 parent f306546
commit aa729bc
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Showing 3 changed files with 47 additions and 16 deletions.
diff --git a/src/providers/wfs/oapif/qgsoapifprovider.cpp b/src/providers/wfs/oapif/qgsoapifprovider.cpp
@@ -214,28 +214,54 @@ QgsWkbTypes::Type QgsOapifProvider::wkbType() const
 
 long long QgsOapifProvider::featureCount() const
 {
-  if ( mUpdateFeatureCountAtNextFeatureCountRequest )
+  // If no filter is set use the fast way of retrieving the feature count
+  if ( mSubsetString.isEmpty() )
   {
-    mUpdateFeatureCountAtNextFeatureCountRequest = false;
+    QString url = mShared->mItemsUrl;
+    url += QStringLiteral( "?limit=1" );
+    url = mShared->appendExtraQueryParameters( url );
+
 
-    QgsFeature f;
-    QgsFeatureRequest request;
-    request.setNoAttributes();
-    auto iter = getFeatures( request );
-    long long count = 0;
-    bool countExact = true;
-    while ( iter.nextFeature( f ) )
+    if ( !mShared->mServerFilter.isEmpty() )
     {
-      if ( count == 1000 ) // to avoid too long processing time
+      url += QStringLiteral( "&" );
+      url += mShared->mServerFilter;
+    }
+
+    QgsOapifItemsRequest itemsRequest( mShared->mURI.uri(), url );
+    if ( !itemsRequest.request( true, false ) )
+      return -1;
+    if ( itemsRequest.errorCode() != QgsBaseNetworkRequest::NoError )
+      return -1;
+
+    mShared->setFeatureCount( itemsRequest.numberMatched(), true );
+  }
+  else // Otherwise the slow way until server side filtering is implemented
+  {
+    if ( mUpdateFeatureCountAtNextFeatureCountRequest )
+    {
+      mUpdateFeatureCountAtNextFeatureCountRequest = false;
+
+      QgsFeature f;
+      QgsFeatureRequest request;
+      request.setNoAttributes();
+      auto iter = getFeatures( request );
+      long long count = 0;
+      bool countExact = true;
+      while ( iter.nextFeature( f ) )
       {
-        countExact = false;
-        break;
+        if ( count == 1000 ) // to avoid too long processing time
+        {
+          countExact = false;
+          break;
+        }
+        count ++;
       }
-      count ++;
-    }
 
-    mShared->setFeatureCount( count, countExact );
+      mShared->setFeatureCount( count, countExact );
+    }
   }
+
   return mShared->getFeatureCount();
 }
 

diff --git a/src/providers/wfs/oapif/qgsoapifprovider.h b/src/providers/wfs/oapif/qgsoapifprovider.h
@@ -212,7 +212,7 @@ class QgsOapifSharedData final: public QObject, public QgsBackgroundCachedShared
 
     bool hasServerSideFilter() const override { return false; }
 
-    bool supportsFastFeatureCount() const override { return false; }
+    bool supportsFastFeatureCount() const override { return mURI.filter().isEmpty(); }
 
     QgsRectangle getExtentFromSingleFeatureRequest() const override { return QgsRectangle(); }
 

diff --git a/tests/src/python/test_provider_oapif.py b/tests/src/python/test_provider_oapif.py
@@ -146,6 +146,7 @@ def setUpClass(cls):
 
         items = {
             "type": "FeatureCollection",
+            "numberMatched": 5,
             "features": [
                 {"type": "Feature", "id": "feat.1",
                  "properties": {"pk": 1, "cnt": 100, "name": "Orange", "name2": "oranGe", "num_char": "1", "dt": "2020-05-03 12:13:14", "date": "2020-05-03", "time": "12:13:14"},
@@ -165,6 +166,10 @@ def setUpClass(cls):
             ]
         }
 
+        # limit 1 for getting count
+        with open(sanitize(endpoint, '/collections/mycollection/items?limit=1&' + ACCEPT_ITEMS), 'wb') as f:
+            f.write(json.dumps(items).encode('UTF-8'))
+
         # first items
         with open(sanitize(endpoint, '/collections/mycollection/items?limit=10&' + ACCEPT_ITEMS), 'wb') as f:
             f.write(json.dumps(items).encode('UTF-8'))