Unexpected read_only behavior

[qrilka]

It looks that read_only doesn't work correctly with WTForms initialization, e.g.:

In [1]: from wtforms_components import read_only

In [2]: from wtforms import Form, TextField

In [3]: class MyForm(Form):
   ...:     foo = TextField()
   ...:     def __init__(self, *args, **kwargs):
   ...:         super(MyForm, self).__init__(*args, **kwargs)
   ...:         read_only(self.foo)
   ...:         

In [4]: from werkzeug.datastructures import MultiDict

In [5]: form=MyForm(MultiDict({'foo':'bar'})
   ...: )

In [6]: form.data
Out[6]: {'foo': 'bar'}

In [7]: form.validate()
Out[7]: True

In [8]: form.data
Out[8]: {'foo': 'bar'}

Is it normal that the field which is supposed to be read-only accepts form data?
I think the problem is in the fact that the field is being modified after form base class constructor where form data gets read

[qrilka]

BTW overriding process method is also not quite correct - it will not fill field with "source object" data, I've done readonly field by overriding process_formdata in my form process method and that seems to give me correct behavior

[tvuotila]

You are correct on why your code works as it does. Form-class constructor calls process-method internally. I have rewrote the code to make the reason more apparent:

In [1]: from wtforms_components import read_only

In [2]: from wtforms import Form, TextField

In [3]: class MyForm(Form):
   ...:         foo = TextField()
   ...:         def __init__(self, *args, **kwargs):
   ...:                 super(MyForm, self).__init__(*args, **kwargs)
   ...:                 

In [4]: from werkzeug.datastructures import MultiDict

In [5]: form = MyForm()

In [6]: form.process(MultiDict({'foo':'bar'}))

In [7]: read_only(form.foo)
Out[7]: <wtforms.fields.simple.TextField at 0x10f14aa50>

In [8]: form.data
Out[8]: {'foo': 'bar'}

In [9]: form.validate()
Out[9]: True

In [10]: form.data
Out[10]: {'foo': 'bar'}

Lets now change the order of two lines:

In [11]: from wtforms_components import read_only

In [12]: from wtforms import Form, TextField

In [13]: class MyForm(Form):
   ....:         foo = TextField()
   ....:         def __init__(self, *args, **kwargs):
   ....:                 super(MyForm, self).__init__(*args, **kwargs)
   ....:                 

In [14]: from werkzeug.datastructures import MultiDict

In [15]: form = MyForm()

In [16]: read_only(form.foo)
Out[16]: <wtforms.fields.simple.TextField at 0x10f14ae10>

In [17]: form.process(MultiDict({'foo':'bar'}))

In [18]: form.data
Out[18]: {'foo': None}

In [19]: form.validate()
Out[19]: True

In [20]: form.data
Out[20]: {'foo': None}

As you can see, the field is read only after read_only-function is called. It makes no difference if I move the function back to constructor.

In [21]: from wtforms_components import read_only

In [22]: from wtforms import Form, TextField

In [23]: class MyForm(Form):
   ....:         foo = TextField()
   ....:         def __init__(self, *args, **kwargs):
   ....:                 super(MyForm, self).__init__(*args, **kwargs)
   ....:                 read_only(self.foo)
   ....:                 

In [24]: from werkzeug.datastructures import MultiDict

In [25]: form = MyForm()

In [26]: form.process(MultiDict({'foo':'bar'}))

In [27]: form.data
Out[27]: {'foo': None}

In [28]: form.validate()
Out[28]: True

In [29]: form.data
Out[29]: {'foo': None}

I know MyForm(MultiDict({'foo':'bar'}) is how examples use forms. It would be nice to set field to read only before constructor is called. Something like foo = read_only(TextField()) or foo = read_only(TextField)(). IMHO