CheckColumns Constraint (#730)

* feat: add check columns class

* feat: write document of check columns part

* test: write a test for check columns constraints

* fix: debuging test exception raise mysql

* fix: set pragma no cover to ignore cov

* fix: ignore pytest raise in python 3.x not 10

* feat: set constraint name for check columns

* refactor: support index and check overwrites

* fix: debuging check constraint arguments

* fix: debug coverage all code tests

* fix: pass the map of type constraint to counter

* refactor: edit check name replace sapce underline

* refactor: write new function copy constraints

* test: write test for invalid constraint type

* fix: debug text cluase replaced names

* fix: set pragma no cover for result returned

* refactor: no coverage for main if statement

* perf: change get constraint copy func code

* fix: fix bug in mypy typing check

ormar/models/helpers/sqlalchemy.py

@@ -298,7 +298,7 @@ def populate_meta_sqlalchemy_table_if_required(meta: "ModelMeta") -> None:
 
 def set_constraint_names(meta: "ModelMeta") -> None:
     """
-    Populates the names on IndexColumn and UniqueColumns constraints.
+    Populates the names on IndexColumns and UniqueColumns and CheckColumns constraints.
 
     :param meta: Meta class of the Model without sqlalchemy table constructed
     :type meta: Model class Meta
@@ -317,6 +317,9 @@ def set_constraint_names(meta: "ModelMeta") -> None:
                 f"ix_{meta.tablename}_"
                 f'{"_".join([col for col in constraint._pending_colargs])}'
             )
+        elif isinstance(constraint, sqlalchemy.CheckConstraint) and not constraint.name:
+            sql_condition: str = str(constraint.sqltext).replace(" ", "_")
+            constraint.name = f"check_{meta.tablename}_{sql_condition}"
 
 
 def update_column_definition(

ormar/models/metaclass.py

@@ -9,6 +9,7 @@ from typing import (
     Type,
     Union,
     cast,
+    Callable,
 )
 
 import databases
@@ -18,6 +19,7 @@ from sqlalchemy.sql.schema import ColumnCollectionConstraint
 
 import ormar  # noqa I100
 import ormar.fields.constraints
+from ormar.fields.constraints import UniqueColumns, IndexColumns, CheckColumns
 from ormar import ModelDefinitionError  # noqa I100
 from ormar.exceptions import ModelError
 from ormar.fields import BaseField
@@ -186,7 +188,7 @@ def verify_constraint_names(
     for column_set in constraints_columns:
         if any(x not in old_aliases.values() for x in column_set):
             raise ModelDefinitionError(
-                f"Unique columns constraint "
+                f"Column constraints "
                 f"{column_set} "
                 f"has column names "
                 f"that are not in the model fields."
@@ -195,6 +197,33 @@ def verify_constraint_names(
             )
 
 
+def get_constraint_copy(
+    constraint: ColumnCollectionConstraint,
+) -> Union[UniqueColumns, IndexColumns, CheckColumns]:
+    """
+    Copy the constraint and unpacking it's values
+
+    :raises ValueError: if non subclass of ColumnCollectionConstraint
+    :param value: an instance of the ColumnCollectionConstraint class
+    :type value: Instance of ColumnCollectionConstraint child
+    :return: copy ColumnCollectionConstraint ormar constraints
+    :rtype: Union[UniqueColumns, IndexColumns, CheckColumns]
+    """
+
+    constraints = {
+        sqlalchemy.UniqueConstraint: lambda x: UniqueColumns(*x._pending_colargs),
+        sqlalchemy.Index: lambda x: IndexColumns(*x._pending_colargs),
+        sqlalchemy.CheckConstraint: lambda x: CheckColumns(x.sqltext),
+    }
+    checks = (key if isinstance(constraint, key) else None for key in constraints)
+    target_class = next((target for target in checks if target is not None), None)
+    constructor: Optional[Callable] = constraints.get(target_class)
+    if not constructor:
+        raise ValueError(f"{constraint} must be a ColumnCollectionMixin!")
+
+    return constructor(constraint)
+
+
 def update_attrs_from_base_meta(  # noqa: CCR001
     base_class: "Model", attrs: Dict, model_fields: Dict
 ) -> None:
@@ -222,10 +251,7 @@ def update_attrs_from_base_meta(  # noqa: CCR001
                     model_fields=model_fields,
                     parent_value=parent_value,
                 )
-                parent_value = [
-                    ormar.fields.constraints.UniqueColumns(*x._pending_colargs)
-                    for x in parent_value
-                ]
+                parent_value = [get_constraint_copy(value) for value in parent_value]
             if isinstance(current_value, list):
                 current_value.extend(parent_value)
             else: