fix: array columns reflection (#119)

Fixes #118

Author: Ilya Gurov

google/cloud/sqlalchemy_spanner/sqlalchemy_spanner.py

@@ -42,6 +42,7 @@
     "STRING": types.String,
     "TIME": types.TIME,
     "TIMESTAMP": types.TIMESTAMP,
+    "ARRAY": types.ARRAY,
 }
 
 _type_map_inv = {
@@ -476,28 +477,43 @@ def get_columns(self, connection, table_name, schema=None, **kw):
             columns = snap.execute_sql(sql)
 
             for col in columns:
-                if col[1].startswith("STRING"):
-                    end = col[1].index(")")
-                    size = int_from_size(col[1][7:end])
-                    type_ = _type_map["STRING"](length=size)
-                # add test creating a table with bytes
-                elif col[1].startswith("BYTES"):
-                    end = col[1].index(")")
-                    size = int_from_size(col[1][6:end])
-                    type_ = _type_map["BYTES"](length=size)
-                else:
-                    type_ = _type_map[col[1]]
-
                 cols_desc.append(
                     {
                         "name": col[0],
-                        "type": type_,
+                        "type": self._designate_type(col[1]),
                         "nullable": col[2] == "YES",
                         "default": None,
                     }
                 )
         return cols_desc
 
+    def _designate_type(self, str_repr):
+        """
+        Designate an SQLAlchemy data type from a Spanner
+        string representation.
+
+        Args:
+            str_repr (str): String representation of a type.
+
+        Returns:
+            An SQLAlchemy data type.
+        """
+        if str_repr.startswith("STRING"):
+            end = str_repr.index(")")
+            size = int_from_size(str_repr[7:end])
+            return _type_map["STRING"](length=size)
+        # add test creating a table with bytes
+        elif str_repr.startswith("BYTES"):
+            end = str_repr.index(")")
+            size = int_from_size(str_repr[6:end])
+            return _type_map["BYTES"](length=size)
+        elif str_repr.startswith("ARRAY"):
+            inner_type_str = str_repr[6:-1]
+            inner_type = self._designate_type(inner_type_str)
+            return _type_map["ARRAY"](inner_type)
+        else:
+            return _type_map[str_repr]
+
     @engine_to_connection
     def get_indexes(self, connection, table_name, schema=None, **kw):
         """Get the table indexes.

test/test_suite.py

@@ -49,6 +49,7 @@
 from sqlalchemy.ext.declarative import declarative_base
 from sqlalchemy.orm import relation
 from sqlalchemy.orm import Session
+from sqlalchemy.types import ARRAY
 from sqlalchemy.types import Integer
 from sqlalchemy.types import Numeric
 from sqlalchemy.types import Text
@@ -901,6 +902,33 @@ def test_binary_reflection(self):
             assert isinstance(typ, LargeBinary)
             eq_(typ.length, 20)
 
+    @testing.requires.table_reflection
+    def test_array_reflection(self):
+        """Check array columns reflection."""
+        orig_meta = self.metadata
+
+        str_array = ARRAY(String(16))
+        int_array = ARRAY(Integer)
+        Table(
+            "arrays_test",
+            orig_meta,
+            Column("id", Integer, primary_key=True),
+            Column("str_array", str_array),
+            Column("int_array", int_array),
+        )
+        orig_meta.create_all()
+
+        # autoload the table and check its columns reflection
+        tab = Table("arrays_test", orig_meta, autoload=True)
+        col_types = [col.type for col in tab.columns]
+        for type_ in (
+            str_array,
+            int_array,
+        ):
+            assert type_ in col_types
+
+        tab.drop()
+
 
 class CompositeKeyReflectionTest(_CompositeKeyReflectionTest):
     @testing.requires.foreign_key_constraint_reflection