prototype for array field

Author: dantownsend

piccolo/columns/base.py

@@ -475,6 +475,11 @@ def get_sql_value(self, value: t.Any) -> t.Any:
             output = f"'{value.isoformat().replace('T', '')}'"
         elif isinstance(value, bytes):
             output = f"'{value.hex()}'"
+        elif isinstance(value, list):
+            # Convert to the array syntax.
+            output = (
+                "'{" + ", ".join([self.get_sql_value(i) for i in value]) + "}'"
+            )
         else:
             output = value
 

piccolo/columns/column_types.py

@@ -52,7 +52,7 @@ def get_querystring(
         value: t.Union[str, Varchar, Text],
         engine_type: str,
         reverse=False,
-    ):
+    ) -> QueryString:
         Concat = ConcatPostgres if engine_type == "postgres" else ConcatSQLite
 
         if isinstance(value, (Varchar, Text)):
@@ -106,7 +106,7 @@ def get_querystring(
         operator: str,
         value: t.Union[int, float, Integer],
         reverse=False,
-    ):
+    ) -> QueryString:
         if isinstance(value, Integer):
             column: Integer = value
             if len(column._meta.call_chain) > 0:
@@ -1343,3 +1343,27 @@ class Blob(Bytea):
     """
 
     pass
+
+
+###############################################################################
+
+
+class Array(Column):
+    value_type = list
+
+    def __init__(
+        self,
+        base_column: Column,
+        default: t.Union[t.List, t.Callable[[], t.List], None] = list,
+        **kwargs,
+    ) -> None:
+        self._validate_default(default, (list, None))
+
+        self.base_column = base_column
+        self.default = default
+        kwargs.update({"base_column": base_column, "default": default})
+        super().__init__(**kwargs)
+
+    @property
+    def column_type(self):
+        return f"{self.base_column.column_type}[]"

tests/columns/test_array.py

@@ -0,0 +1,32 @@
+from unittest import TestCase
+
+from piccolo.table import Table
+from piccolo.columns.column_types import Array, Integer
+
+from ..base import postgres_only
+
+
+class MyTable(Table):
+    value = Array(base_column=Integer())
+
+
+@postgres_only
+class TestArrayPostgres(TestCase):
+    """
+    Make sure an Array column can be created.
+    """
+
+    def setUp(self):
+        MyTable.create_table().run_sync()
+
+    def tearDown(self):
+        MyTable.alter().drop_table().run_sync()
+
+    def test_storage(self):
+        """
+        Make sure data can be stored and retrieved.
+        """
+        MyTable(value=[1, 2, 3]).save().run_sync()
+
+        row = MyTable.objects().first().run_sync()
+        self.assertEqual(row.value, [1, 2, 3])