IRIS ListBuild as a Column type

sqlalchemy_iris/__init__.py

@@ -24,6 +24,7 @@
 from .base import TINYINT
 from .base import VARBINARY
 from .base import VARCHAR
+from .base import IRISListBuild
 
 base.dialect = dialect = iris.dialect
 
@@ -45,5 +46,6 @@
     "TINYINT",
     "VARBINARY",
     "VARCHAR",
+    "IRISListBuild",
     "dialect",
 ]

sqlalchemy_iris/base.py

@@ -91,6 +91,7 @@ def check_constraints(cls):
 from .types import IRISDate
 from .types import IRISDateTime
 from .types import IRISUniqueIdentifier
+from .types import IRISListBuild
 
 
 ischema_names = {

sqlalchemy_iris/types.py

@@ -1,7 +1,9 @@
 import datetime
 from decimal import Decimal
 from sqlalchemy.sql import sqltypes
+from sqlalchemy.types import UserDefinedType
 from uuid import UUID as _python_UUID
+from intersystems_iris import IRISList
 
 HOROLOG_ORDINAL = datetime.date(1840, 12, 31).toordinal()
 
@@ -194,6 +196,47 @@ def process(value):
                 return None
 
 
+class IRISListBuild(UserDefinedType):
+    cache_ok = True
+
+    def __init__(self, max_items: int = None, item_type: type = float):
+        super(UserDefinedType, self).__init__()
+        self.max_items = max_items
+        max_length = None
+        if type is float or type is int:
+            max_length = max_items * 10
+        elif max_items:
+            max_length = 65535
+        self.max_length = max_length
+
+    def get_col_spec(self, **kw):
+        if self.max_length is None:
+            return "VARBINARY(65535)"
+        return "VARBINARY(%d)" % self.max_length
+
+    def bind_processor(self, dialect):
+        def process(value):
+            irislist = IRISList()
+            if not value:
+                return value
+            if not isinstance(value, list) and not isinstance(value, tuple):
+                raise ValueError("expected list or tuple, got '%s'" % type(value))
+            for item in value:
+                irislist.add(item)
+            return irislist.getBuffer()
+
+        return process
+
+    def result_processor(self, dialect, coltype):
+        def process(value):
+            if value:
+                irislist = IRISList(value)
+                return irislist._list_data
+            return value
+
+        return process
+
+
 class BIT(sqltypes.TypeEngine):
     __visit_name__ = "BIT"
 
@@ -212,3 +255,7 @@ class LONGVARCHAR(sqltypes.VARCHAR):
 
 class LONGVARBINARY(sqltypes.VARBINARY):
     __visit_name__ = "LONGVARBINARY"
+
+
+class LISTBUILD(sqltypes.VARBINARY):
+    __visit_name__ = "VARCHAR"

tests/test_suite.py

@@ -18,6 +18,7 @@
 from sqlalchemy.types import VARBINARY
 from sqlalchemy.types import BINARY
 from sqlalchemy_iris import TINYINT
+from sqlalchemy_iris import IRISListBuild
 from sqlalchemy.exc import DatabaseError
 import pytest
 
@@ -281,3 +282,42 @@ class BizarroCharacterFKResolutionTest(_BizarroCharacterFKResolutionTest):
     )
     def test_fk_ref(self, connection, metadata, use_composite, tablename, columnname):
         super().test_fk_ref(connection, metadata, use_composite, tablename, columnname)
+
+
+class IRISListBuildTest(fixtures.TablesTest):
+    __backend__ = True
+
+    @classmethod
+    def define_tables(cls, metadata):
+        Table(
+            "data",
+            metadata,
+            Column("val", IRISListBuild(10, float)),
+        )
+
+    @classmethod
+    def fixtures(cls):
+        return dict(
+            data=(
+                ("val",),
+                ([1.0] * 50,),
+                ([1.23] * 50,),
+                ([i for i in range(0, 50)],),
+                (None,),
+            )
+        )
+
+    def _assert_result(self, select, result):
+        with config.db.connect() as conn:
+            eq_(conn.execute(select).fetchall(), result)
+
+    def test_listbuild(self):
+        self._assert_result(
+            select(self.tables.data),
+            [
+                ([1.0] * 50,),
+                ([1.23] * 50,),
+                ([i for i in range(0, 50)],),
+                (None,),
+            ],
+        )