Add size parameter

Author: WaVEV

django_mongodb_backend/fields/array.py

@@ -10,6 +10,7 @@
 from ..forms import SimpleArrayField
 from ..query_utils import process_lhs, process_rhs
 from ..utils import prefix_validation_error
+from .validators import LengthValidator
 
 __all__ = ["ArrayField"]
 
@@ -27,14 +28,23 @@ class ArrayField(CheckFieldDefaultMixin, Field):
     }
     _default_hint = ("list", "[]")
 
-    def __init__(self, base_field, max_size=None, **kwargs):
+    def __init__(self, base_field, max_size=None, size=None, **kwargs):
         self.base_field = base_field
         self.max_size = max_size
+        self.size = size
+        if size and max_size:
+            raise ValueError("Cannot define both, size and max_size")
         if self.max_size:
             self.default_validators = [
                 *self.default_validators,
                 ArrayMaxLengthValidator(self.max_size),
             ]
+        if self.size:
+            self.default_validators = [
+                *self.default_validators,
+                ArrayMaxLengthValidator(self.size),
+                LengthValidator(self.size),
+            ]
         # For performance, only add a from_db_value() method if the base field
         # implements it.
         if hasattr(self.base_field, "from_db_value"):
@@ -125,10 +135,7 @@ def deconstruct(self):
         if path == "django_mongodb_backend.fields.array.ArrayField":
             path = "django_mongodb_backend.fields.ArrayField"
         kwargs.update(
-            {
-                "base_field": self.base_field.clone(),
-                "max_size": self.max_size,
-            }
+            {"base_field": self.base_field.clone(), "max_size": self.max_size, "size": self.size}
         )
         return name, path, args, kwargs
 

django_mongodb_backend/fields/validators.py

@@ -0,0 +1,19 @@
+from django.core.validators import BaseValidator
+from django.utils.deconstruct import deconstructible
+from django.utils.translation import ngettext_lazy
+
+
+@deconstructible
+class LengthValidator(BaseValidator):
+    message = ngettext_lazy(
+        "List contains %(show_value)d item, it should contain %(limit_value)d.",
+        "List contains %(show_value)d items, it should contain %(limit_value)d.",
+        "show_value",
+    )
+    code = "length"
+
+    def compare(self, a, b):
+        return a != b
+
+    def clean(self, x):
+        return len(x)

tests/model_fields_/test_arrayfield.py

@@ -817,6 +817,23 @@ def test_with_max_size_singular(self):
         with self.assertRaisesMessage(exceptions.ValidationError, msg):
             field.clean([1, 2], None)
 
+    def test_with_size(self):
+        field = ArrayField(models.IntegerField(), size=3)
+        field.clean([1, 2, 3], None)
+        with self.assertRaises(exceptions.ValidationError) as cm:
+            field.clean([1, 2, 3, 4], None)
+        self.assertEqual(
+            cm.exception.messages[0],
+            "List contains 4 items, it should contain 3.",
+        )
+
+    def test_with_size_singular(self):
+        field = ArrayField(models.IntegerField(), size=2)
+        field.clean([1, 2], None)
+        msg = "List contains 1 item, it should contain 2."
+        with self.assertRaisesMessage(exceptions.ValidationError, msg):
+            field.clean([1], None)
+
     def test_nested_array_mismatch(self):
         field = ArrayField(ArrayField(models.IntegerField()))
         field.clean([[1, 2], [3, 4]], None)

tests/validators_/__init__.py

@@ -0,0 +1,14 @@
+from django.core.exceptions import ValidationError
+from django.test import SimpleTestCase
+
+from django_mongodb_backend.fields.validators import LengthValidator
+
+
+class TestValidators(SimpleTestCase):
+    def test_validators(self):
+        validator = LengthValidator(10)
+        with self.assertRaises(ValidationError):
+            validator([])
+        with self.assertRaises(ValidationError):
+            validator(list(range(11)))
+        self.assertEqual(validator(list(range(10))), None)