Various tweaks to the overlay_contains function description and examples

qgis · Oct 15, 2020 · cb37b18 · cb37b18
1 parent 748aa4c
commit cb37b18
Showing 1 changed file with 16 additions and 12 deletions.
diff --git a/resources/function_help/json/overlay_contains b/resources/function_help/json/overlay_contains
@@ -2,50 +2,54 @@
   "name": "overlay_contains",
   "type": "function",
   "groups": ["GeometryGroup"],
-  "description": "Performs a spatial join of type CONTAINS. This returns an array of results of an expression evaluated on features from a different layer that CONTAINS the current feature, or, if no expression if provided, simply returns whether at least one feature from the other layer CONTAINS the current feature.",
+  "description": "Returns whether the current feature spatially contains at least one feature from a target layer, or an array of expression-based results for the features in the target layer contained in the current feature.<br><br>Read more on the underlying GEOS \"Contains\" predicate, as described in PostGIS <a href='https://postgis.net/docs/ST_Contains.html'>ST_CONTAINS</a> function.",
   "arguments": [
     {
       "arg": "layer",
-      "description": "the other layer"
+      "description": "the layer whose overlay is checked"
     },
     {
       "arg": "expression",
-      "description": "an optional expression to evaluate on the features from the other layer (if not set, the function will just return a boolean indicating whether there is at least one match)",
+      "description": "an optional expression to evaluate on the features from the target layer. If not set, the function will just return a boolean indicating whether there is at least one match.",
       "optional": true
     },
     {
       "arg": "filter",
-      "description": "an optional expression to filter the matching features (if not set, all features will be returned)",
+      "description": "an optional expression to filter the target features to check. If not set, all the features will be checked.",
       "optional": true
     },
     {
       "arg": "limit",
-      "description": "an optional integer to limit the number of matching features (if not set, all features will be returned)",
+      "description": "an optional integer to limit the number of matching features. If not set, all the matching features will be returned.",
       "optional": true
     },
     {
       "arg": "cache",
       "description": "set this to true to build a local spatial index (most of the time, this is unwanted, unless you are working with a particularly slow data provider)",
       "optional": true,
-      "default": false
+      "default": "false"
     }
   ],
   "examples": [
     {
       "expression": "overlay_contains('regions')",
-      "returns": "True"
+      "returns": "true if the current feature spatially contains a region"
+    },
+    {
+      "expression": "overlay_contains('regions', filter:= population > 10000)",
+      "returns": "true if the current feature spatially contains a region with a population greater than 10000"
     },
     {
       "expression": "overlay_contains('regions', name)",
-      "returns": "['South Africa', 'Africa', 'World']"
+      "returns": "an array of names, for the regions contained in the current feature"
     },
     {
-      "expression": "overlay_contains('regions', name, name != 'World')",
-      "returns": "['South Africa', 'Africa']"
+      "expression": "array_sort(overlay_contains(layer:='regions', expression:=\"name\", filter:= population > 10000))",
+      "returns": "an ordered array of names, for the regions contained in the current feature and with a population greater than 10000"
     },
     {
-      "expression": "overlay_contains('regions', name, limit:=1)",
-      "returns": "['South Africa']"
+      "expression": "overlay_contains(layer:='regions', expression:= geom_to_wkt($geometry), limit:=2)",
+      "returns": "an array of geometries (in WKT), for up to two regions contained in the current feature"
     }
   ]
 }