New model form generator: Support of BinaryField, FileField, ImageField

example_app/app.py

@@ -3,6 +3,7 @@
 from pymongo import monitoring
 
 from example_app import views
+from example_app.binary_demo import binary_demo_view
 from example_app.boolean_demo import boolean_demo_view
 from example_app.dates_demo import dates_demo_view
 from example_app.dict_demo import dict_demo_view
@@ -55,6 +56,8 @@
 app.add_url_rule("/bool/<pk>/", view_func=boolean_demo_view, methods=["GET", "POST"])
 app.add_url_rule("/dict", view_func=dict_demo_view, methods=["GET", "POST"])
 app.add_url_rule("/dict/<pk>/", view_func=dict_demo_view, methods=["GET", "POST"])
+app.add_url_rule("/binary", view_func=binary_demo_view, methods=["GET", "POST"])
+app.add_url_rule("/binary/<pk>/", view_func=binary_demo_view, methods=["GET", "POST"])
 
 if __name__ == "__main__":
     app.run(host="0.0.0.0", port=8000)

example_app/binary_demo.py

@@ -0,0 +1,20 @@
+"""Strings and strings related fields demo model."""
+
+from example_app.models import db
+
+
+class BinaryDemoModel(db.Document):
+    """Documentation example model."""
+
+    string_field = db.StringField()
+    binary_field = db.BinaryField()
+    binary_field_with_default = db.BinaryField(default=lambda: "foobar".encode("utf-8"))
+    file_field = db.FileField()
+    image_field = db.ImageField()
+
+
+def binary_demo_view(pk=None):
+    """Return all fields demonstration."""
+    from example_app.views import demo_view
+
+    return demo_view(model=BinaryDemoModel, view_name=binary_demo_view.__name__, pk=pk)

example_app/boolean_demo.py

@@ -17,9 +17,6 @@ class BooleanDemoModel(db.Document):
     )
 
 
-BooleanDemoForm = BooleanDemoModel.to_wtf_form()
-
-
 def boolean_demo_view(pk=None):
     """Return all fields demonstration."""
     from example_app.views import demo_view

example_app/dates_demo.py

@@ -22,9 +22,6 @@ class DateTimeModel(db.Document):
     )
 
 
-DateTimeDemoForm = DateTimeModel.to_wtf_form()
-
-
 def dates_demo_view(pk=None):
     """Return all fields demonstration."""
     from example_app.views import demo_view

example_app/dict_demo.py

@@ -24,9 +24,6 @@ class DictDemoModel(db.Document):
     )
 
 
-DictDemoForm = DictDemoModel.to_wtf_form()
-
-
 def dict_demo_view(pk=None):
     """Return all fields demonstration."""
     from example_app.views import demo_view

example_app/numbers_demo.py

@@ -19,9 +19,6 @@ class NumbersDemoModel(db.Document):
     integer_field_limited = db.IntField(min_value=1, max_value=200)
 
 
-NumbersDemoForm = NumbersDemoModel.to_wtf_form()
-
-
 def numbers_demo_view(pk=None):
     """Return all fields demonstration."""
     from example_app.views import demo_view

example_app/strings_demo.py

@@ -25,9 +25,6 @@ class StringsDemoModel(db.Document):
     url_field = db.URLField()
 
 
-StringsDemoForm = StringsDemoModel.to_wtf_form()
-
-
 def strings_demo_view(pk=None):
     """Return all fields demonstration."""
     from example_app.views import demo_view

example_app/templates/form_demo.html

@@ -30,7 +30,7 @@
     {{ render_navigation(page, view) }}
   </div>
   <div>
-    <form method="POST">
+    <form method="POST" enctype="multipart/form-data">
       {% for field in form %}
         {{ render_field(field, style='font-weight: bold') }}
       {% endfor %}

example_app/templates/layout.html

@@ -23,6 +23,7 @@
     <li><a href="{{ url_for("dates_demo_view") }}">DateTime demo</a></li>
     <li><a href="{{ url_for("boolean_demo_view") }}">Booleans demo</a></li>
     <li><a href="{{ url_for("dict_demo_view") }}">Dict/Json demo</a></li>
+    <li><a href="{{ url_for("binary_demo_view") }}">Binary/Files/Images demo</a></li>
   </ul>
 </nav>
 <div>

example_app/views.py

@@ -4,11 +4,6 @@
 from mongoengine.context_managers import switch_db
 
 from example_app import models
-from example_app.boolean_demo import BooleanDemoModel
-from example_app.dates_demo import DateTimeModel
-from example_app.dict_demo import DictDemoModel
-from example_app.numbers_demo import NumbersDemoModel
-from example_app.strings_demo import StringsDemoModel
 
 
 def generate_data():
@@ -50,15 +45,10 @@ def generate_data():
 
 def delete_data():
     """Clear database."""
-    with switch_db(models.Todo, "default"):
-        models.Todo.objects().delete()
-        BooleanDemoModel.objects().delete()
-        DateTimeModel.objects().delete()
-        DictDemoModel.objects().delete()
-        StringsDemoModel.objects().delete()
-        NumbersDemoModel.objects().delete()
-    with switch_db(models.Todo, "secondary"):
-        models.Todo.objects().delete()
+    from example_app.app import db
+
+    db.connection["default"].drop_database("example_app")
+    db.connection["secondary"].drop_database("example_app_2")
 
 
 def index():

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):
@@ -590,20 +577,7 @@ class FileField(WtfFieldMixin, fields.FileField):
     All arguments should be passed as keyword arguments, to exclude unexpected behaviour.
     """
 
-    DEFAULT_WTF_FIELD = wtf_fields.FileField if wtf_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.MongoFileField if custom_fields else None
 
 
 class FloatField(WtfFieldMixin, fields.FloatField):
@@ -751,18 +725,15 @@ class ImageField(WtfFieldMixin, fields.ImageField):
     All arguments should be passed as keyword arguments, to exclude unexpected behaviour.
     """
 
-    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.
+    DEFAULT_WTF_FIELD = custom_fields.MongoImageField if custom_fields else None
 
-        :raises NotImplementedError: Field converter to WTForm Field not implemented.
-        """
-        raise NotImplementedError("Field converter to WTForm Field not implemented.")
+    @property
+    @wtf_required
+    def wtf_generated_options(self) -> dict:
+        """Inserts accepted type in widget rendering (does not do validation)."""
+        options = super().wtf_generated_options
+        options["render_kw"] = {"accept": "image/*"}
+        return options
 
 
 class IntField(WtfFieldMixin, fields.IntField):

flask_mongoengine/wtf/fields.py

@@ -9,9 +9,13 @@
 
 from flask import json
 from mongoengine.queryset import DoesNotExist
+from werkzeug.datastructures import FileStorage
 from wtforms import fields as wtf_fields
 from wtforms import validators as wtf_validators
 from wtforms import widgets as wtf_widgets
+from wtforms.utils import unset_value
+
+from flask_mongoengine.wtf import widgets as mongo_widgets
 
 
 def coerce_boolean(value: Optional[str]) -> Optional[bool]:
@@ -31,6 +35,14 @@ def coerce_boolean(value: Optional[str]) -> Optional[bool]:
         raise ValueError("Unexpected string value.")
 
 
+def _is_empty_file(file_object):
+    """Detects empty files and file streams."""
+    file_object.seek(0)
+    first_char = file_object.read(1)
+    file_object.seek(0)
+    return not bool(first_char)
+
+
 # noinspection PyAttributeOutsideInit,PyAbstractClass
 class QuerySetSelectField(wtf_fields.SelectFieldBase):
     """
@@ -309,6 +321,26 @@ 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 +357,6 @@ 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
@@ -351,6 +381,53 @@ class MongoEmailField(EmptyStringIsNoneMixin, wtf_fields.EmailField):
     pass
 
 
+class MongoFileField(wtf_fields.FileField):
+    """GridFS file field."""
+
+    widget = mongo_widgets.MongoFileInput()
+
+    def __init__(self, **kwargs):
+        """Extends base field arguments with file delete marker."""
+        super().__init__(**kwargs)
+
+        self._should_delete = False
+        self._marker = f"_{self.name}_delete"
+
+    def process(self, formdata, data=unset_value, extra_filters=None):
+        """Extracts 'delete' marker option, if exists in request."""
+        if formdata and self._marker in formdata:
+            self._should_delete = True
+        return super().process(formdata, data=data, extra_filters=extra_filters)
+
+    def populate_obj(self, obj, name):
+        """Upload, replace or delete file from database, according form action."""
+        field = getattr(obj, name, None)
+
+        if field is None:
+            return None
+
+        if self._should_delete:
+            field.delete()
+            return None
+
+        if isinstance(self.data, FileStorage) and not _is_empty_file(self.data.stream):
+            action = field.replace if field.grid_id else field.put
+            action(
+                self.data.stream,
+                filename=self.data.filename,
+                content_type=self.data.content_type,
+            )
+
+
+class MongoFloatField(wtf_fields.FloatField):
+    """
+    Regular :class:`wtforms.fields.FloatField`, with widget replaced to
+    :class:`wtforms.widgets.NumberInput`.
+    """
+
+    widget = wtf_widgets.NumberInput(step="any")
+
+
 class MongoHiddenField(EmptyStringIsNoneMixin, wtf_fields.HiddenField):
     """
     Regular :class:`wtforms.fields.HiddenField`, that transform empty string to `None`.
@@ -359,6 +436,12 @@ class MongoHiddenField(EmptyStringIsNoneMixin, wtf_fields.HiddenField):
     pass
 
 
+class MongoImageField(MongoFileField):
+    """GridFS image field."""
+
+    widget = mongo_widgets.MongoImageInput()
+
+
 class MongoPasswordField(EmptyStringIsNoneMixin, wtf_fields.PasswordField):
     """
     Regular :class:`wtforms.fields.PasswordField`, that transform empty string to `None`.
@@ -407,15 +490,6 @@ class MongoURLField(EmptyStringIsNoneMixin, wtf_fields.URLField):
     pass
 
 
-class MongoFloatField(wtf_fields.FloatField):
-    """
-    Regular :class:`wtforms.fields.FloatField`, with widget replaced to
-    :class:`wtforms.widgets.NumberInput`.
-    """
-
-    widget = wtf_widgets.NumberInput(step="any")
-
-
 class MongoDictField(MongoTextAreaField):
     """Form field to handle JSON in :class:`~flask_mongoengine.db_fields.DictField`."""
 

flask_mongoengine/wtf/widgets.py

@@ -0,0 +1,40 @@
+"""Custom widgets for Mongo fields."""
+from markupsafe import Markup, escape
+from mongoengine.fields import GridFSProxy, ImageGridFsProxy
+from wtforms.widgets.core import FileInput
+
+
+class MongoFileInput(FileInput):
+    """Renders a file input field with delete option."""
+
+    template = """
+        <div>
+        <i class="icon-file"></i>%(name)s %(size)dk (%(content_type)s)
+        <input type="checkbox" name="%(marker)s">Delete</input>
+        </div>
+        """
+
+    def _is_supported_file(self, field) -> bool:
+        """Checks type of file input."""
+        return field.data and isinstance(field.data, GridFSProxy)
+
+    def __call__(self, field, **kwargs) -> Markup:
+        placeholder = ""
+
+        if self._is_supported_file(field):
+            placeholder = self.template % {
+                "name": escape(field.data.name),
+                "content_type": escape(field.data.content_type),
+                "size": field.data.length // 1024,
+                "marker": f"_{field.name}_delete",
+            }
+
+        return Markup(placeholder) + super().__call__(field, **kwargs)
+
+
+class MongoImageInput(MongoFileInput):
+    """Renders an image input field with delete option."""
+
+    def _is_supported_file(self, field) -> bool:
+        """Checks type of file input."""
+        return field.data and isinstance(field.data, ImageGridFsProxy)