added array support to sqlite

Author: dantownsend

piccolo/columns/column_types.py

@@ -1366,4 +1366,9 @@ def __init__(
 
     @property
     def column_type(self):
-        return f"{self.base_column.column_type}[]"
+        engine_type = self._meta.table._meta.db.engine_type
+        if engine_type == "postgres":
+            return f"{self.base_column.column_type}[]"
+        elif engine_type == "sqlite":
+            return "ARRAY"
+        raise Exception("Unrecognized engine type")

piccolo/engine/sqlite.py

@@ -14,6 +14,8 @@
 from piccolo.engine.exceptions import TransactionError
 from piccolo.query.base import Query
 from piccolo.querystring import QueryString
+
+from piccolo.utils.encoding import dump_json, load_json
 from piccolo.utils.sync import run_sync
 
 ###############################################################################
@@ -39,14 +41,14 @@ def convert_uuid_in(value) -> str:
     return str(value)
 
 
-def convert_time_in(value) -> str:
+def convert_time_in(value: datetime.time) -> str:
     """
     Converts the time value being passed into sqlite.
     """
     return value.isoformat()
 
 
-def convert_date_in(value):
+def convert_date_in(value: datetime.date):
     """
     Converts the date value being passed into sqlite.
     """
@@ -64,13 +66,24 @@ def convert_datetime_in(value: datetime.datetime) -> str:
     return str(value)
 
 
-def convert_timedelta_in(value):
+def convert_timedelta_in(value: datetime.timedelta):
     """
     Converts the timedelta value being passed into sqlite.
     """
     return value.total_seconds()
 
 
+def convert_array_in(value: list):
+    """
+    Converts a list value into a string.
+    """
+    if len(value) > 0:
+        if type(value[0]) not in [str, int, float]:
+            raise ValueError("Can only serialise str, int and float.")
+
+    return dump_json(value)
+
+
 # Out
 
 
@@ -129,6 +142,14 @@ def convert_timestamptz_out(value: bytes) -> datetime.datetime:
     return datetime.datetime.fromisoformat(value.decode("utf8"))
 
 
+def convert_array_out(value: bytes) -> t.List:
+    """
+    If the value if from an array column, deserialise the string back into a
+    list.
+    """
+    return load_json(value.decode("utf8"))
+
+
 sqlite3.register_converter("Numeric", convert_numeric_out)
 sqlite3.register_converter("Integer", convert_int_out)
 sqlite3.register_converter("UUID", convert_uuid_out)
@@ -137,13 +158,15 @@ def convert_timestamptz_out(value: bytes) -> datetime.datetime:
 sqlite3.register_converter("Seconds", convert_seconds_out)
 sqlite3.register_converter("Boolean", convert_boolean_out)
 sqlite3.register_converter("Timestamptz", convert_timestamptz_out)
+sqlite3.register_converter("Array", convert_array_out)
 
 sqlite3.register_adapter(Decimal, convert_numeric_in)
 sqlite3.register_adapter(uuid.UUID, convert_uuid_in)
 sqlite3.register_adapter(datetime.time, convert_time_in)
 sqlite3.register_adapter(datetime.date, convert_date_in)
 sqlite3.register_adapter(datetime.datetime, convert_datetime_in)
 sqlite3.register_adapter(datetime.timedelta, convert_timedelta_in)
+sqlite3.register_adapter(list, convert_array_in)
 
 ###############################################################################
 

piccolo/utils/encoding.py

@@ -16,3 +16,10 @@ def dump_json(data: t.Any) -> str:
         return orjson.dumps(data, default=str).decode("utf8")
     else:
         return json.dumps(data, default=str)
+
+
+def load_json(data: str) -> t.Any:
+    if ORJSON:
+        return orjson.loads(data)
+    else:
+        return json.loads(data)

tests/columns/test_array.py

@@ -3,14 +3,11 @@
 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.

tests/utils/test_encoding.py

@@ -0,0 +1,12 @@
+from unittest import TestCase
+
+from piccolo.utils.encoding import dump_json, load_json
+
+
+class TestEncodingDecoding(TestCase):
+    def test_dump_load(self):
+        """
+        Test dumping then loading an object.
+        """
+        payload = {"a": [1, 2, 3]}
+        self.assertEqual(load_json(dump_json(payload)), payload)