953 Add array_columns to Table._meta (#954)

* add `TableMeta.array_columns`

* fix black warning

piccolo/table.py

@@ -78,6 +78,7 @@ class TableMeta:
     columns: t.List[Column] = field(default_factory=list)
     default_columns: t.List[Column] = field(default_factory=list)
     non_default_columns: t.List[Column] = field(default_factory=list)
+    array_columns: t.List[Array] = field(default_factory=list)
     email_columns: t.List[Email] = field(default_factory=list)
     foreign_key_columns: t.List[ForeignKey] = field(default_factory=list)
     primary_key: Column = field(default_factory=Column)
@@ -267,6 +268,7 @@ def __init_subclass__(
         columns: t.List[Column] = []
         default_columns: t.List[Column] = []
         non_default_columns: t.List[Column] = []
+        array_columns: t.List[Array] = []
         foreign_key_columns: t.List[ForeignKey] = []
         secret_columns: t.List[Secret] = []
         json_columns: t.List[t.Union[JSON, JSONB]] = []
@@ -304,6 +306,7 @@ def __init_subclass__(
 
                 if isinstance(column, Array):
                     column._setup_base_column(table_class=cls)
+                    array_columns.append(column)
 
                 if isinstance(column, Email):
                     email_columns.append(column)
@@ -337,6 +340,7 @@ def __init_subclass__(
             columns=columns,
             default_columns=default_columns,
             non_default_columns=non_default_columns,
+            array_columns=array_columns,
             email_columns=email_columns,
             primary_key=primary_key,
             foreign_key_columns=foreign_key_columns,
@@ -809,9 +813,11 @@ def is_unquoted(arg):
         # If unquoted, dump it straight into the query.
         query = ",".join(
             [
-                args_dict[column._meta.name].value
-                if is_unquoted(args_dict[column._meta.name])
-                else "{}"
+                (
+                    args_dict[column._meta.name].value
+                    if is_unquoted(args_dict[column._meta.name])
+                    else "{}"
+                )
                 for column in self._meta.columns
             ]
         )
@@ -995,9 +1001,11 @@ def _process_column_args(
         Convert any string arguments to column instances.
         """
         return [
-            cls._meta.get_column_by_name(column)
-            if (isinstance(column, str))
-            else column
+            (
+                cls._meta.get_column_by_name(column)
+                if (isinstance(column, str))
+                else column
+            )
             for column in columns
         ]
 

tests/table/test_metaclass.py

@@ -5,6 +5,7 @@
 from piccolo.columns.column_types import (
     JSON,
     JSONB,
+    Array,
     Email,
     ForeignKey,
     Varchar,
@@ -132,6 +133,17 @@ class MyTable(Table):
 
         self.assertEqual(MyTable._meta.email_columns, [MyTable.column_a])
 
+    def test_arry_columns(self):
+        """
+        Make sure ``TableMeta.array_columns`` are setup correctly.
+        """
+
+        class MyTable(Table):
+            column_a = Array(Varchar())
+            column_b = Varchar()
+
+        self.assertEqual(MyTable._meta.array_columns, [MyTable.column_a])
+
     def test_id_column(self):
         """
         Makes sure an id column is added.