How to properly add column headers into WTForms dynamic selectfield list

Question

I have a Pandas dataframe and trying to return the column headers into WTForm dynamic list on a Flask application. However when I try to submit the HTML form, I get a validation error. Here is my form class error.

   data = pd.read_excel("sampledata.xlsx")
   col_headers = list(data.columns)

   col_list = list(col_headers)
   dic_list = {i : col_list[i] for i in range(0, len(col_list))}


   class StatementForm(FlaskForm):
   date = SelectField('Date', choices = [(key, dic_list[key]) for key in dic_list])

I have tested the HTML form by manually inputting a tuple in the choices list and it worked. Apparently the problem is in the 'date' parameter and the choices.

Your help in reviwing the code is most apreciated.

Try str(key) in your choices comprehension. In my experience the SelectField does not like integer keys. — Woody Pride
– Woody Pride, Commented May 17, 2019 at 18:30
Also, you can get rid of some steps by doing: choices = [(str(x), y) for (x, y) in list(enumerate(data.columns))] and do it all in one line. Let me know if this works — Woody Pride
– Woody Pride, Commented May 17, 2019 at 18:34
@snakecharmerb There is nothing much to show on the console, the validation rules stops the code from loading. Here is the screenshot pasteboard.co/IfaeH7r.png — Zion Oyemade
– Zion Oyemade, Commented May 17, 2019 at 20:17
@WoodyPride it kind of worked because my form now displays the column header values and submits. However I noticed whenever the data is called it is the Key or index ID that is outputted. form = StatementForm() date = form.date.data date returns an index number — Zion Oyemade
– Zion Oyemade, Commented May 18, 2019 at 7:31
@WoodyPride Please drop your comment as an answer so I can accept it. I was able to resolve the outputted Index ID - This solution from stackoverflow.com/questions/21217475/… worked. — Zion Oyemade
– Zion Oyemade, Commented May 18, 2019 at 8:39

Woody Pride · Accepted Answer · 2019-05-20 14:18:43Z

1

Try using the following to create your choices:

choices = [(str(x), y) for (x, y) in list(enumerate(data.columns))]

The difference is that that value in the above code is a string. As per the WFT-Forms documentation:

Select fields keep a choices property which is a sequence of (value, label) pairs. The value portion can be any type in theory, but as form data is sent by the browser as strings, you will need to provide a function which can coerce the string representation back to a comparable object.

In your version you are trying to pass integers as the value, so that is why it is breaking.

answered May 20, 2019 at 14:18

Woody Pride

14k10 gold badges51 silver badges64 bronze badges

Sign up to request clarification or add additional context in comments.

Collectives™ on Stack Overflow

How to properly add column headers into WTForms dynamic selectfield list

1 Answer 1

Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related