Add in forms support of BinaryField

Author: insspb

example_app/binary_demo.py

@@ -8,6 +8,7 @@ class BinaryDemoModel(db.Document):
 
     string_field = db.StringField()
     binary_field = db.BinaryField()
+    binary_field_with_default = db.BinaryField(default=lambda: "foobar".encode("utf-8"))
 
 
 def binary_demo_view(pk=None):

flask_mongoengine/db_fields.py

@@ -305,20 +305,7 @@ class BinaryField(WtfFieldMixin, fields.BinaryField):
     All arguments should be passed as keyword arguments, to exclude unexpected behaviour.
     """
 
-    DEFAULT_WTF_FIELD = custom_fields.BinaryField if custom_fields else None
-
-    def to_wtf_field(
-        self,
-        *,
-        model: Optional[Type] = None,
-        field_kwargs: Optional[dict] = None,
-    ):
-        """
-        Protection from execution of :func:`to_wtf_field` in form generation.
-
-        :raises NotImplementedError: Field converter to WTForm Field not implemented.
-        """
-        raise NotImplementedError("Field converter to WTForm Field not implemented.")
+    DEFAULT_WTF_FIELD = custom_fields.MongoBinaryField if custom_fields else None
 
 
 class BooleanField(WtfFieldMixin, fields.BooleanField):

flask_mongoengine/wtf/fields.py

@@ -309,6 +309,26 @@ def process_formdata(self, valuelist):
             super().process_formdata(valuelist)
 
 
+# noinspection PyAttributeOutsideInit
+class MongoBinaryField(wtf_fields.TextAreaField):
+    """
+    Special WTForm :class:`~.wtforms.fields.TextAreaField` that convert input to binary.
+    """
+
+    def process_formdata(self, valuelist):
+        """Converts string form value to binary type and ignoring empty form fields."""
+        if not valuelist or valuelist[0] == "":
+            self.data = None
+        else:
+            self.data = valuelist[0].encode("utf-8")
+
+    def _value(self):
+        """
+        Ensures that encoded string data will not be encoded once more on form edit.
+        """
+        return self.data.decode("utf-8") if self.data is not None else ""
+
+
 class MongoBooleanField(wtf_fields.SelectField):
     """Mongo SelectField field for BooleanFields, that correctly coerce values."""
 
@@ -325,8 +345,6 @@ def __init__(
         Replaces defaults of :class:`wtforms.fields.SelectField` with for Boolean values.
 
         Fully compatible with :class:`wtforms.fields.SelectField` and have same parameters.
-
-
         """
         if coerce is None:
             coerce = coerce_boolean

tests/test_db_fields.py

@@ -148,7 +148,6 @@ def test__ensure_callable_or_list__raise_error_if_argument_not_callable_and_not_
     @pytest.mark.parametrize(
         "FieldClass",
         [
-            db_fields.BinaryField,
             db_fields.CachedReferenceField,
             db_fields.DynamicField,
             db_fields.EmbeddedDocumentField,