Python bindings: Accept str arg in FeatureDefn.GetFieldDefn

autotest/ogr/ogr_basic_test.py

@@ -662,6 +662,21 @@ def test_ogr_basic_16():
     assert list(ogr_basic_16_gen_list(2)) == [0, 1]
 
 
+def test_ogr_basic_getfielddefn():
+
+    defn = ogr.FeatureDefn()
+    defn.AddFieldDefn(ogr.FieldDefn("intfield", ogr.OFTInteger))
+
+    by_index = defn.GetFieldDefn(0)
+    by_name = defn.GetFieldDefn("intfield")
+
+    assert by_index.this == by_name.this
+
+    with gdaltest.enable_exceptions():
+        with pytest.raises(Exception, match="Invalid"):
+            defn.GetFieldDefn("does_not_exist")
+
+
 def test_ogr_basic_invalid_unicode():
 
     val = "\udcfc"

swig/include/python/docs/ogr_featuredef_docs.i

@@ -87,26 +87,24 @@ int:
     count of fields.
 ";
 
-%feature("docstring")  GetFieldDefn "OGRFieldDefnH
-OGR_FD_GetFieldDefn(OGRFeatureDefnH hDefn, int iField)
+%feature("docstring")  GetFieldDefn "
 
 Fetch field definition of the passed feature definition.
 
-This function is the same as the C++ method
-OGRFeatureDefn::GetFieldDefn().
+See :cpp:func:`OGRFeatureDefn::GetFieldDefn`.
 
 Parameters
 -----------
-hDefn:
-    handle to the feature definition to get the field definition from.
-iField:
-    the field to fetch, between 0 and GetFieldCount()-1.
+i : int / str
+    Field name or 0-based numeric index. For repeated
+    access, use of the numeric index avoids a lookup
+    step.
 
 Returns
 --------
-OGRFieldDefnH:
-    a handle to an internal field definition object or NULL if invalid
-    index. This object should not be modified or freed by the application.
+FieldDefn:
+    internal field definition object or ``None`` if the field does not
+    exist. This object should not be modified by the application.
 ";
 
 %feature("docstring")  AddFieldDefn "void
@@ -548,4 +546,4 @@ int:
     TRUE if the feature definition is identical to the other one.
 ";
 
-}
+}

swig/include/python/ogr_python.i

@@ -1156,6 +1156,11 @@ def ReleaseResultSet(self, sql_lyr):
     self.thisown = 0
 
 }
+
+%feature("pythonprepend") GetFieldDefn %{
+    if type(args[0]) is str:
+        args = (self.GetFieldIndex(args[0]), )
+%}
 }
 
 %extend OGRFieldDefnShadow {