Fixed #19139 -- Made OpenLayersWidget follow GeoModelAdmin's modifiable attribute

Thanks Tim Graham for the review.

django/contrib/gis/admin/widgets.py

@@ -22,6 +22,9 @@ class OpenLayersWidget(Textarea):
         # Update the template parameters with any attributes passed in.
         if attrs:
             self.params.update(attrs)
+            self.params['editable'] = self.params['modifiable']
+        else:
+            self.params['editable'] = True
 
         # Defaulting the WKT value to a blank string -- this
         # will be tested in the JavaScript and the appropriate

django/contrib/gis/templates/gis/admin/openlayers.html

@@ -31,7 +31,9 @@
 //]]>
 </script>
 <div id="{{ id }}_map"{% if LANGUAGE_BIDI %} dir="ltr"{% endif %}></div>
+{% if editable %}
 <a href="javascript:{{ module }}.clearFeatures()">Delete all Features</a>
+{% endif %}
 {% if display_wkt %}<p> WKT debugging window:</p>{% endif %}
 <textarea id="{{ id }}" class="vWKTField required" cols="150" rows="10" name="{{ name }}">{{ wkt }}</textarea>
 <script type="text/javascript">{% block init_function %}{{ module }}.init();{% endblock %}</script>

django/contrib/gis/tests/geoadmin/admin.py

+from django.contrib.gis import admin
+
+
+class UnmodifiableAdmin(admin.OSMGeoAdmin):
+    modifiable = False

django/contrib/gis/tests/geoadmin/tests.py

@@ -7,6 +7,7 @@ if HAS_GEOS:
     from django.contrib.gis import admin
     from django.contrib.gis.geos import Point
 
+    from .admin import UnmodifiableAdmin
     from .models import City
 
 
@@ -20,13 +21,31 @@ class GeoAdminTest(TestCase):
         self.assertTrue(any(geoadmin.openlayers_url in js for js in admin_js))
 
     def test_olmap_OSM_rendering(self):
-        geoadmin = admin.site._registry[City]
-        result = geoadmin.get_map_widget(City._meta.get_field('point'))(
-        ).render('point', Point(-79.460734, 40.18476))
+        delete_all_btn = """<a href="javascript:geodjango_point.clearFeatures()">Delete all Features</a>"""
+
+        original_geoadmin = admin.site._registry[City]
+        params = original_geoadmin.get_map_widget(City._meta.get_field('point')).params
+        result = original_geoadmin.get_map_widget(City._meta.get_field('point'))(
+        ).render('point', Point(-79.460734, 40.18476), params)
         self.assertIn(
             """geodjango_point.layers.base = new OpenLayers.Layer.OSM("OpenStreetMap (Mapnik)");""",
             result)
 
+        self.assertIn(delete_all_btn, result)
+
+        admin.site.unregister(City)
+        admin.site.register(City, UnmodifiableAdmin)
+        try:
+            geoadmin = admin.site._registry[City]
+            params = geoadmin.get_map_widget(City._meta.get_field('point')).params
+            result = geoadmin.get_map_widget(City._meta.get_field('point'))(
+            ).render('point', Point(-79.460734, 40.18476), params)
+
+            self.assertNotIn(delete_all_btn, result)
+        finally:
+            admin.site.unregister(City)
+            admin.site.register(City, original_geoadmin.__class__)
+
     def test_olmap_WMS_rendering(self):
         geoadmin = admin.GeoModelAdmin(City, admin.site)
         result = geoadmin.get_map_widget(City._meta.get_field('point'))(