initial support for geopackage metatata issue#713

fiona/collection.py

@@ -221,6 +221,87 @@ def crs_wkt(self):
             self._crs_wkt = self.session.get_crs_wkt()
         return self._crs_wkt
 
+    def tags(self, ns=None):
+        """Returns a dict containing copies of the dataset or layers's
+        tags. Tags are pairs of key and value strings. Tags belong to
+        namespaces.  The standard namespaces are: default (None) and
+        'IMAGE_STRUCTURE'.  Applications can create their own additional
+        namespaces.
+
+        Parameters
+        ----------
+        ns: str, optional
+            Can be used to select a namespace other than the default.
+
+        Returns
+        -------
+        dict
+        """
+        if self.session:
+            return self.session.tags(ns=ns)
+        return None
+
+    def get_tag_item(self, key, ns=None):
+        """Returns tag item value
+
+        Parameters
+        ----------
+        key: str
+            The key for the metadata item to fetch.
+        ns: str, optional
+            Used to select a namespace other than the default.
+
+        Returns
+        -------
+        str
+        """
+        if self.session:
+            return self.session.get_tag_item(key=key, ns=ns)
+        return None
+
+    def set_tags(self, tags, ns=None):
+        """Writes a dict containing the dataset or layers's tags.
+        Tags are pairs of key and value strings. Tags belong to
+        namespaces.  The standard namespaces are: default (None) and
+        'IMAGE_STRUCTURE'.  Applications can create their own additional
+        namespaces.
+
+        Parameters
+        ----------
+        tags: dict
+            The dict of metadata items to set.
+        ns: str, optional
+            Used to select a namespace other than the default.
+
+        Returns
+        -------
+        int
+        """
+        if isinstance(self.session, WritingSession):
+            return self.session.set_tags(tags, ns=ns)
+        raise RuntimeError("Unable to set tags as not in writing mode.")
+
+    def set_tag_item(self, key, tag, ns=None):
+        """Sets the tag item value
+
+        Parameters
+        ----------
+        key: str
+            The key for the metadata item to set.
+        tag: str
+            The value of the metadata item to set.
+        ns: str, optional
+            Used to select a namespace other than the default.
+
+        Returns
+        -------
+        int
+        """
+        if isinstance(self.session, WritingSession):
+            return self.session.set_tag_item(key=key, tag=tag, ns=ns)
+        raise RuntimeError("Unable to set tag item as not in writing mode.")
+
+
     @property
     def meta(self):
         """Returns a mapping with the driver, schema, crs, and additional

fiona/ogrext.pyx

@@ -1,7 +1,8 @@
 # These are extension functions and classes using the OGR C API.
-
 from __future__ import absolute_import
 
+include "gdal.pxi"
+
 import datetime
 import json
 import locale
@@ -822,6 +823,76 @@ cdef class Session:
             return 0
 
 
+    def tags(self, ns=None):
+        """Returns a dict containing copies of the dataset or layers's
+        tags. Tags are pairs of key and value strings. Tags belong to
+        namespaces.  The standard namespaces are: default (None) and
+        'IMAGE_STRUCTURE'.  Applications can create their own additional
+        namespaces.
+
+        Parameters
+        ----------
+        ns: str, optional
+            Can be used to select a namespace other than the default.
+
+        Returns
+        -------
+        dict
+        """
+        cdef GDALMajorObjectH obj = NULL
+        if self.cogr_layer != NULL:
+            obj = self.cogr_layer
+        else:
+            obj = self.cogr_ds
+
+        cdef const char *domain = NULL
+        if ns:
+            ns = ns.encode('utf-8')
+            domain = ns
+
+        cdef char **metadata = NULL
+        metadata = GDALGetMetadata(obj, domain)
+        num_items = CSLCount(metadata)
+
+        return dict(metadata[i].decode('utf-8').split('=', 1) for i in range(num_items))
+
+
+    def get_tag_item(self, key, ns=None):
+        """Returns tag item value
+
+        Parameters
+        ----------
+        key: str
+            The key for the metadata item to fetch.
+        ns: str, optional
+            Used to select a namespace other than the default.
+
+        Returns
+        -------
+        str
+        """
+
+        key = key.encode('utf-8')
+        cdef const char *name = key
+
+        cdef const char *domain = NULL
+        if ns:
+            ns = ns.encode('utf-8')
+            domain = ns
+
+        cdef GDALMajorObjectH obj = NULL
+        if self.cogr_layer != NULL:
+            obj = self.cogr_layer
+        else:
+            obj = self.cogr_ds
+
+        cdef char *value = NULL
+        value = GDALGetMetadataItem(obj, name, domain)
+        if value == NULL:
+            return None
+        return value.decode("utf-8")
+
+
 cdef class WritingSession(Session):
 
     cdef object _schema_mapping
@@ -1210,6 +1281,80 @@ cdef class WritingSession(Session):
         gdal_flush_cache(cogr_ds)
         log.debug("Flushed data source cache")
 
+    def set_tags(self, tags, ns=None):
+        """Writes a dict containing the dataset or layers's tags.
+        Tags are pairs of key and value strings. Tags belong to
+        namespaces.  The standard namespaces are: default (None) and
+        'IMAGE_STRUCTURE'.  Applications can create their own additional
+        namespaces.
+
+        Parameters
+        ----------
+        tags: dict
+            The dict of metadata items to set.
+        ns: str, optional
+            Used to select a namespace other than the default.
+
+        Returns
+        -------
+        int
+        """
+        cdef GDALMajorObjectH obj = NULL
+        if self.cogr_layer != NULL:
+            obj = self.cogr_layer
+        else:
+            obj = self.cogr_ds
+
+        cdef const char *domain = NULL
+        if ns:
+            ns = ns.encode('utf-8')
+            domain = ns
+
+        cdef char **metadata = NULL
+        try:
+            for key, value in tags.items():
+                key = key.encode("utf-8")
+                value = value.encode("utf-8")
+                metadata = CSLAddNameValue(metadata, <const char *>key, <const char *>value)
+            return GDALSetMetadata(obj, metadata, domain)
+        finally:
+            CSLDestroy(metadata)
+
+    def set_tag_item(self, key, tag, ns=None):
+        """Sets the tag item value
+
+        Parameters
+        ----------
+        key: str
+            The key for the metadata item to set.
+        tag: str
+            The value of the metadata item to set.
+        ns: str
+            Used to select a namespace other than the default.
+
+        Returns
+        -------
+        int
+        """
+        key = key.encode('utf-8')
+        cdef const char *name = key
+        tag = tag.encode("utf-8")
+        cdef char *value = tag
+
+        cdef const char *domain = NULL
+        if ns:
+            ns = ns.encode('utf-8')
+            domain = ns
+
+        cdef GDALMajorObjectH obj = NULL
+        if self.cogr_layer != NULL:
+            obj = self.cogr_layer
+        else:
+            obj = self.cogr_ds
+
+        return GDALSetMetadataItem(obj, name, value, domain)
+
+
 cdef class Iterator:
 
     """Provides iterated access to feature data.

tests/test_session.py

@@ -1,4 +1,5 @@
 """Tests of the ogrext.Session class"""
+import pytest
 
 import fiona
 
@@ -7,3 +8,49 @@ def test_get(path_coutwildrnp_shp):
     with fiona.open(path_coutwildrnp_shp) as col:
         feat3 = col.get(2)
         assert feat3['properties']['NAME'] == 'Mount Zirkel Wilderness'
+
+
+@pytest.mark.parametrize("layer, namespace, tags", [
+    (None, None, {"test_tag1": "test_value1", "test_tag2": "test_value2"}),
+    (None, "test", {"test_tag1": "test_value1", "test_tag2": "test_value2"}),
+    (None, None, {}),
+    (None, "test", {}),  
+    ("layer", None, {"test_tag1": "test_value1", "test_tag2": "test_value2"}),
+    ("layer", "test", {"test_tag1": "test_value1", "test_tag2": "test_value2"}),
+    ("layer", None, {}),
+    ("layer", "test", {}),  
+])
+def test_set_tags(layer, namespace, tags, tmpdir):
+    test_geopackage = str(tmpdir.join("test.gpkg"))
+    schema = {'properties': {'CDATA1': 'str:254'}, 'geometry': 'Polygon'}
+    with fiona.open(test_geopackage, "w", driver="GPKG", schema=schema, layer=layer) as gpkg:
+        assert gpkg.tags() == {}
+        gpkg.set_tags(tags, ns=namespace)
+
+    with fiona.open(test_geopackage, layer=layer) as gpkg:
+        assert gpkg.tags(ns=namespace) == tags
+        if namespace is not None:
+            assert gpkg.tags() == {}
+        with pytest.raises(RuntimeError):
+            gpkg.set_tags({}, ns=namespace)
+
+
+@pytest.mark.parametrize("layer, namespace", [
+    (None, None),
+    (None, "test"),
+    ("test", None),
+    ("test", "test"),
+])
+def test_set_tag_item(layer, namespace, tmpdir):
+    test_geopackage = str(tmpdir.join("test.gpkg"))
+    schema = {'properties': {'CDATA1': 'str:254'}, 'geometry': 'Polygon'}
+    with fiona.open(test_geopackage, "w", driver="GPKG", schema=schema, layer=layer) as gpkg:
+        assert gpkg.get_tag_item("test_tag1", ns=namespace) is None
+        gpkg.set_tag_item("test_tag1", "test_value1", ns=namespace)
+
+    with fiona.open(test_geopackage, layer=layer) as gpkg:
+        if namespace is not None:
+            assert gpkg.get_tag_item("test_tag1") is None
+        assert gpkg.get_tag_item("test_tag1", ns=namespace) == "test_value1"
+        with pytest.raises(RuntimeError):
+            gpkg.set_tag_item("test_tag1", "test_value1", ns=namespace)