Add support for config file properties to PostgreSQL provider (#829)

* 🐛 Add support for the properties keyword from the config file

* 🚨 Fixed flake8 errors

* ✅ Added a test for config properties

pygeoapi/provider/postgresql.py

@@ -60,7 +60,7 @@ class DatabaseConnection:
      The class returns a connection object.
     """
 
-    def __init__(self, conn_dic, table, context="query"):
+    def __init__(self, conn_dic, table, properties=[], context="query"):
         """
         PostgreSQLProvider Class constructor returning
 
@@ -81,15 +81,17 @@ class DatabaseConnection:
 
         :param table: table name containing the data. This variable is used to
                 assemble column information
+        :param properties: User-specified subset of column names to expose
         :param context: query or hits, if query then it will determine
                 table column otherwise will not do it
-        :returns: psycopg2.extensions.connection
+        :returns: DatabaseConnection
         """
 
         self.conn_dic = conn_dic
         self.table = table
         self.context = context
         self.columns = None
+        self.properties = properties
         self.fields = {}  # Dict of columns. Key is col name, value is type
         self.conn = None
 
@@ -117,6 +119,8 @@ class DatabaseConnection:
 
             self.cur.execute(query_cols)
             result = self.cur.fetchall()
+            if self.properties:
+                result = [res for res in result if res[0] in self.properties]
             self.columns = SQL(', ').join(
                 [Identifier(item[0]) for item in result]
                 )
@@ -173,7 +177,9 @@ class PostgreSQLProvider(BaseProvider):
         :returns: dict of fields
         """
         if not self.fields:
-            with DatabaseConnection(self.conn_dic, self.table) as db:
+            with DatabaseConnection(self.conn_dic,
+                                    self.table,
+                                    properties=self.properties) as db:
                 self.fields = db.fields
         return self.fields
 
@@ -246,7 +252,9 @@ class PostgreSQLProvider(BaseProvider):
         if resulttype == 'hits':
 
             with DatabaseConnection(self.conn_dic,
-                                    self.table, context="hits") as db:
+                                    self.table,
+                                    properties=self.properties,
+                                    context="hits") as db:
                 cursor = db.conn.cursor(cursor_factory=RealDictCursor)
 
                 where_clause = self.__get_where_clauses(
@@ -266,7 +274,9 @@ class PostgreSQLProvider(BaseProvider):
 
         end_index = startindex + limit
 
-        with DatabaseConnection(self.conn_dic, self.table) as db:
+        with DatabaseConnection(self.conn_dic,
+                                self.table,
+                                properties=self.properties) as db:
             cursor = db.conn.cursor(cursor_factory=RealDictCursor)
 
             props = db.columns if select_properties == [] else \
@@ -364,7 +374,9 @@ class PostgreSQLProvider(BaseProvider):
         """
 
         LOGGER.debug('Get item from Postgis')
-        with DatabaseConnection(self.conn_dic, self.table) as db:
+        with DatabaseConnection(self.conn_dic,
+                                self.table,
+                                properties=self.properties) as db:
             cursor = db.conn.cursor(cursor_factory=RealDictCursor)
 
             sql_query = SQL("SELECT {},ST_AsGeoJSON({}) \

tests/test_postgresql_provider.py

@@ -57,9 +57,15 @@ def config():
     }
 
 
+@pytest.fixture()
+def config_with_properties(config):
+    config_ = {'properties': ['name', 'waterway', 'width', 'does_not_exist']}
+    config_.update(config)
+    return config_
+
+
 def test_query(config):
     """Testing query for a valid JSON object with geometry"""
-
     p = PostgreSQLProvider(config)
     feature_collection = p.query()
     assert feature_collection.get('type', None) == 'FeatureCollection'
@@ -73,7 +79,7 @@ def test_query(config):
 
 
 def test_query_with_property_filter(config):
-    """Test query  valid features when filtering by property"""
+    """Test query valid features when filtering by property"""
     p = PostgreSQLProvider(config)
     feature_collection = p.query(properties=[("waterway", "stream")])
     features = feature_collection.get('features', None)
@@ -94,6 +100,20 @@ def test_query_with_property_filter(config):
     assert (len(other_features) != 0)
 
 
+def test_query_with_config_properties(config_with_properties):
+    """
+    Test that query is restricted by properties in the config.
+    No properties should be returned that are not requested.
+    Note that not all requested properties have to exist in the query result.
+    """
+    p = PostgreSQLProvider(config_with_properties)
+    feature_collection = p.query()
+    feature = feature_collection.get('features', None)[0]
+    properties = feature.get('properties', None)
+    for property_name in properties.keys():
+        assert property_name in config_with_properties["properties"]
+
+
 def test_query_hits(config):
     """Test query resulttype=hits with properties"""
     psp = PostgreSQLProvider(config)