WMS: add buildGetMapURL()

docs/source/usage.rst

@@ -73,6 +73,9 @@ Result:
    :height: 250px
    :alt: WMS GetMap generated by OWSLib
 
+To fetch the image with another HTTP client, ``buildGetMapURL`` takes the same parameters
+and returns the URL without sending a request.
+
 
 WFS
 ---

owslib/map/wms111.py

@@ -271,6 +271,20 @@ def getmap(self, layers=None, styles=None, srs=None, bbox=None,
             raise ServiceException(err_message)
         return u
 
+    def buildGetMapURL(self, **kwargs):
+        """Return the URL that getmap(method='Get') would request, without sending it.
+
+        Takes the same parameters as getmap(), except method and timeout.
+        """
+        kwargs.setdefault('bgcolor', '#FFFFFF')
+        kwargs.setdefault('exceptions', 'application/vnd.ogc.se_xml')
+        try:
+            base_url = next((m.get('url') for m in self.getOperationByName('GetMap').methods
+                            if m.get('type').lower() == 'get'))
+        except StopIteration:
+            base_url = self.url
+        return bind_url(base_url) + urlencode(self.__build_getmap_request(**kwargs))
+
     def getfeatureinfo(self,
                        layers=None,
                        styles=None,

owslib/map/wms130.py

@@ -323,6 +323,20 @@ def getmap(self, layers=None,
             raise ServiceException(err_message)
         return u
 
+    def buildGetMapURL(self, **kwargs):
+        """Return the URL that getmap(method='Get') would request, without sending it.
+
+        Takes the same parameters as getmap(), except method and timeout.
+        """
+        kwargs.setdefault('bgcolor', '#FFFFFF')
+        kwargs.setdefault('exceptions', 'XML')
+        try:
+            base_url = next((m.get('url') for m in self.getOperationByName('GetMap').methods
+                            if m.get('type').lower() == 'get'))
+        except StopIteration:
+            base_url = self.url
+        return bind_url(base_url) + urlencode(self.__build_getmap_request(**kwargs))
+
     def getfeatureinfo(self, layers=None,
                        styles=None,
                        srs=None,

tests/test_wms_getmap.py

@@ -1,7 +1,7 @@
 from unittest import mock
 
 import pytest
-from tests.utils import service_ok
+from tests.utils import resource_file, service_ok
 
 from owslib.wms import WebMapService
 from owslib.map.wms130 import WebMapService_1_3_0
@@ -38,6 +38,22 @@ def test_build_getmap_request_bbox_precision(version):
     assert request['bbox'] == ','.join(map(str, bbox_yx))
 
 
+@pytest.mark.parametrize("version, caps", [("1.3.0", "wms_mesonet-caps-130.xml"), ("1.1.1", "wms_mesonet-caps.xml")])
+def test_build_getmap_url(version, caps):
+    """buildGetMapURL returns the URL getmap would request"""
+    with open(resource_file(caps), 'rb') as f:
+        wms = WebMapService(SERVICE_URL, version=version, xml=f.read())
+    params = dict(layers=['nexrad_base_reflect'], srs='EPSG:4326', bbox=(-126, 24, -66, 50),
+                  size=(250, 250), format='image/png', time='2006-06-23T03:10:00Z')
+
+    response = mock.Mock()
+    response.info.return_value = {'Content-Type': 'image/png'}
+    with mock.patch(f"owslib.map.wms{version.replace('.', '')}.openURL", return_value=response):
+        wms.getmap(**params)
+
+    assert wms.buildGetMapURL(**params) == wms.request
+
+
 @pytest.mark.online
 @pytest.mark.skipif(not service_ok(SERVICE_URL),
                     reason="WMS service is unreachable")