Django set field value after a form is initialized

Question

I am trying to set the field to a certain value after the form is initialized    For example  I have the following class   class CustomForm forms Form       Email   forms EmailField min length 1  max length 200    In the view  I want to be able to do something like this   form   CustomForm   form  Email     GetEmailString    return HttpResponse t render c

User · Answer

If you ve already initialized the form  you can use the initial property of the field  For example    form   CustomForm   form fields  Email   initial   GetEmailString

User · Answer

If you have initialized the form like this  form   CustomForm     then the correct way as of Jan 2019  is to use  initial to replace the data  This will replace the data in the intial dict that goes along with the form  It also works if you have initialized using some instance such as  form   CustomForm instance instance   To replace data in the form  you need to  form initial  Email     GetEmailString     Generalizing this it would be   form initial  field name     new value

User · Answer

in widget use  value  attr  Example   username   forms CharField      required False      widget forms TextInput attrs   readonly   True   value    CONSTANT VALUE

User · Answer

Something like Nigel Cohen s would work if you were adding data to a copy of the collected set of form data   form   FormType request POST  if request method     POST       formcopy   form request POST copy        formcopy data  Email     GetEmailString

User · Answer

Another way to do this  if you have already initialised a form  with or without data   and you need to add further data before displaying it   form   Form request POST form  form data  Email     GetEmailString

User · Answer

To throw yet another way into the mix  this works too  with a bit more modern notation  It just works around the fact that a QueryDict is immutable    gt  gt  gt  the form data      f data dict     some field   47   gt  gt  gt  the form  some field   as widget     lt input type  hidden  name  some field  value  47          class  field-some field  id  id some field  gt

User · Answer

If you want to do it within the form s   init   method for some reason  you can manipulate the initial dict   class MyForm forms Form       my field   forms CharField max length 255       def   init   self   args    kwargs           super MyForm  self    init    args    kwargs          self initial  my field      Initial value

User · Answer

Since you re not passing in POST data  I ll assume that what you are trying to do is set an initial value that will be displayed in the form  The way you do this is with the initial keyword   form   CustomForm initial   Email   GetEmailString       See the Django Form docs for more explanation   If you are trying to change a value after the form was submitted  you can use something like   if form is valid        form cleaned data  Email     GetEmailString     Check the referenced docs above for more on using cleaned data

User · Answer

Just change your Form data field   class ChooseProjectForm forms Form       project   forms ModelChoiceField queryset project qs      my projects   forms BooleanField        def   init   self   args    kwargs           super ChooseProjectForm  self    init    args    kwargs          self data   self data copy      IMPORTANT  self data is immutable           any condition          if self data get  my projects                my projects   self fields  project   queryset filter my True              self fields  project   queryset   my projects             self fields  project   initial   my projects first   pk             self fields  project   empty label   None    disable  -----              self data update project my projects first   pk     Update Form data             self fields  project   widget   forms HiddenInput      Hide if you want

[django] Django set field value after a form is initialized

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