How do I filter ForeignKey choices in a Django ModelForm

Question

Say I have the following in my models py   class Company models Model      name        class Rate models Model      company   models ForeignKey Company     name        class Client models Model      name          company   models ForeignKey Company     base rate   models ForeignKey Rate    I e  there are multiple Companies  each having a range of Rates and Clients   Each Client should have a base Rate that is chosen from it s parent Company s Rates  not another Company s Rates   When creating a form for adding a Client  I would like to remove the Company choices  as that has already been selected via an  Add Client  button on the Company page  and limit the Rate choices to that Company as well   How do I go about this in Django 1 0     My current forms py file is just boilerplate at the moment   from models import   from django forms import ModelForm  class ClientForm ModelForm       class Meta          model   Client   And the views py is also basic   from django shortcuts import render to response  get object or 404 from models import   from forms import    def addclient request  company id       the company   get object or 404 Company  id company id       if request POST          form   ClientForm request POST          if form is valid                form save               return HttpResponseRedirect the company get clients url        else          form   ClientForm        return render to response  addclient html     form   form   the company  the company     In Django 0 96 I was able to hack this in by doing something like the following before rendering the template   manipulator fields 0  choices     r id r name  for r in Rate objects filter company id the company id     ForeignKey limit choices to seems promising but I don t know how to pass in the company id and I m not clear if that will work outside the Admin interface anyway   Thanks    This seems like a pretty basic request but if I should redesign something I m open to suggestions

User · Accepted Answer

ForeignKey is represented by django forms ModelChoiceField  which is a ChoiceField whose choices are a model QuerySet   See the reference for ModelChoiceField   So  provide a QuerySet to the field s queryset attribute   Depends on how your form is built   If you build an explicit form  you ll have fields named directly    form rate queryset   Rate objects filter company id the company id    If you take the default ModelForm object  form fields  rate   queryset        This is done explicitly in the view   No hacking around

User · Answer

If you haven t created the form and want to change the queryset you can do   formmodel base fields  myfield   queryset   MyModel objects filter        This is pretty useful when you are using generic views

User · Answer

A more public way is by calling get form in Admin classes  It also works for non-database fields too  For example here i have a field called   terminal list  on the form that can be used in special cases for choosing several terminal items from get list request   then filtering based on request user   class ChangeKeyValueForm forms ModelForm          terminal list   forms ModelMultipleChoiceField   queryset Terminal objects all          class Meta          model   ChangeKeyValue         fields      terminal list    param path    param value    scheduled time        class ChangeKeyValueAdmin admin ModelAdmin       form   ChangeKeyValueForm     list display     terminal   task list    plugin   last update time       list per page  16      def get form self  request  obj   None    kwargs           form   super ChangeKeyValueAdmin  self  get form request    kwargs          qs  filterargs   Terminal get list request          form base fields   terminal list   queryset   qs         return form

User · Answer

This is simple  and works with Django 1 4   class ClientAdminForm forms ModelForm       def   init   self   args    kwargs           super ClientAdminForm  self    init    args    kwargs            access object through self instance            self fields  base rate   queryset   Rate objects filter company self instance company   class ClientAdmin admin ModelAdmin       form   ClientAdminForm            You don t need to specify this in a form class  but can do it directly in the ModelAdmin  as Django already includes this built-in method on the ModelAdmin  from the docs    ModelAdmin formfield for foreignkey self  db field  request    kwargs       The formfield for foreignkey method on a ModelAdmin allows you to     override the default formfield for a foreign keys field  For example      to return a subset of objects for this foreign key field based on the    user      class MyModelAdmin admin ModelAdmin       def formfield for foreignkey self  db field  request    kwargs           if db field name     car               kwargs  queryset     Car objects filter owner request user          return super MyModelAdmin  self  formfield for foreignkey db field  request    kwargs    An even niftier way to do this  for example in creating a front-end admin interface that users can access  is to subclass the ModelAdmin and then alter the methods below   The net result is a user interface that ONLY shows them content that is related to them  while allowing you  a super-user  to see everything   I ve overridden four methods  the first two make it impossible for a user to delete anything  and it also removes the delete buttons from the admin site     The third override filters any query that contains a reference to  in the example  user  or  porcupine   just as an illustration      The last override filters any foreignkey field in the model to filter the choices available the same as the basic queryset     In this way  you can present an easy to manage front-facing admin site that allows users to mess with their own objects  and you don t have to remember to type in the specific ModelAdmin filters we talked about above     class FrontEndAdmin models ModelAdmin       def   init   self  model  admin site           self model   model         self opts   model  meta         self admin site   admin site         super FrontEndAdmin  self    init   model  admin site    remove  delete  buttons       def get actions self  request           actions   super FrontEndAdmin  self  get actions request          if  delete selected  in actions              del actions  delete selected           return actions   prevents delete permission      def has delete permission self  request  obj None           return False   filters objects that can be viewed on the admin site       def get queryset self  request           if request user is superuser              try                  qs   self model objects all               except AttributeError                  qs   self model  default manager get queryset               return qs          else              try                  qs   self model objects all               except AttributeError                  qs   self model  default manager get queryset                if hasattr self model     user                      return qs filter user request user              if hasattr self model     porcupine                      return qs filter porcupine request user porcupine              else                  return qs   filters choices for all foreignkey fields on the admin site       def formfield for foreignkey self  db field  request    kwargs           if request employee is superuser              return super FrontEndAdmin  self  formfield for foreignkey db field  request    kwargs           else              if hasattr db field rel to   user                    kwargs  queryset     db field rel to objects filter user request user              if hasattr db field rel to   porcupine                    kwargs  queryset     db field rel to objects filter porcupine request user porcupine              return super ModelAdminFront  self  formfield for foreignkey db field  request    kwargs

User · Answer

So  I ve really tried to understand this  but it seems that Django still doesn t make this very straightforward   I m not all that dumb  but I just can t see any  somewhat  simple solution   I find it generally pretty ugly to have to override the Admin views for this sort of thing  and every example I find never fully applies to the Admin views   This is such a common circumstance with the models I make that I find it appalling that there s no obvious solution to this     I ve got these classes     models py class Company models Model             class Contract models Model       company   models ForeignKey Company      locations   models ManyToManyField  Location   class Location models Model       company   models ForeignKey Company    This creates a problem when setting up the Admin for Company  because it has inlines for both Contract and Location  and Contract s m2m options for Location are not properly filtered according to the Company that you re currently editing   In short  I would need some admin option to do something like this     admin py class LocationInline admin TabularInline       model   Location class ContractInline admin TabularInline       model   Contract class CompanyAdmin admin ModelAdmin       inlines    ContractInline  LocationInline      inline filter   dict Location  company  self     Ultimately I wouldn t care if the filtering process was placed on the base CompanyAdmin  or if it was placed on the ContractInline    Placing it on the inline makes more sense  but it makes it hard to reference the base Contract as  self     Is there anyone out there who knows of something as straightforward as this badly needed shortcut   Back when I made PHP admins for this sort of thing  this was considered basic functionality   In fact  it was always automatic  and had to be disabled if you really didn t want it

User · Answer

If you haven t created the form and want to change the queryset you can do   formmodel base fields  myfield   queryset   MyModel objects filter        This is pretty useful when you are using generic views

User · Answer

In addition to S Lott s answer and as becomingGuru mentioned in comments  its possible to add the queryset filters by overriding the ModelForm   init   function   This could easily apply to regular forms  it can help with reuse and keeps the view function tidy    class ClientForm forms ModelForm       def   init   self company  args   kwargs           super  ClientForm self     init    args   kwargs    populates the post         self fields  rate   queryset   Rate objects filter company company          self fields  client   queryset   Client objects filter company company       class Meta          model   Client  def addclient request  company id           the company   get object or 404 Company  id company id           if request POST              form   ClientForm the company request POST     lt -- Note the extra arg             if form is valid                    form save                   return HttpResponseRedirect the company get clients url            else              form   ClientForm the company           return render to response  addclient html                                        form   form   the company  the company     This can be useful for reuse say if you have common filters needed on many models  normally I declare an abstract Form class   E g   class UberClientForm ClientForm       class Meta          model   UberClient  def view request               form   UberClientForm company            or even extend the existing custom init class PITAClient ClientForm       def   init   company   args    args           super  PITAClient self     init   company  args   kwargs          self fields  support staff   queryset   User objects exclude user  michael     Other than that I m just restating Django blog material of which there are many good ones out there

User · Answer

So  I ve really tried to understand this  but it seems that Django still doesn t make this very straightforward   I m not all that dumb  but I just can t see any  somewhat  simple solution   I find it generally pretty ugly to have to override the Admin views for this sort of thing  and every example I find never fully applies to the Admin views   This is such a common circumstance with the models I make that I find it appalling that there s no obvious solution to this     I ve got these classes     models py class Company models Model             class Contract models Model       company   models ForeignKey Company      locations   models ManyToManyField  Location   class Location models Model       company   models ForeignKey Company    This creates a problem when setting up the Admin for Company  because it has inlines for both Contract and Location  and Contract s m2m options for Location are not properly filtered according to the Company that you re currently editing   In short  I would need some admin option to do something like this     admin py class LocationInline admin TabularInline       model   Location class ContractInline admin TabularInline       model   Contract class CompanyAdmin admin ModelAdmin       inlines    ContractInline  LocationInline      inline filter   dict Location  company  self     Ultimately I wouldn t care if the filtering process was placed on the base CompanyAdmin  or if it was placed on the ContractInline    Placing it on the inline makes more sense  but it makes it hard to reference the base Contract as  self     Is there anyone out there who knows of something as straightforward as this badly needed shortcut   Back when I made PHP admins for this sort of thing  this was considered basic functionality   In fact  it was always automatic  and had to be disabled if you really didn t want it

User · Answer

To do this with a generic view  like CreateView     class AddPhotoToProject CreateView               a view where a user can associate a photo with a project             model   Connection     form class   CreateConnectionForm       def get context data self    kwargs           context   super AddPhotoToProject  self  get context data   kwargs          context  photo     self kwargs  pk           context  form   fields  project   queryset   Project objects for user self request user          return context     def form valid self  form           pobj   Photo objects get pk self kwargs  pk            obj   form save commit False          obj photo   pobj         obj save            return json     success   True           if self request is ajax                 final response   json dumps return json              return HttpResponse final response           else               messages success self request   photo was added to project                return HttpResponseRedirect reverse  MyPhotos      the most important part of that         context  form   fields  project   queryset   Project objects for user self request user      read my post here

User · Answer

A more public way is by calling get form in Admin classes  It also works for non-database fields too  For example here i have a field called   terminal list  on the form that can be used in special cases for choosing several terminal items from get list request   then filtering based on request user   class ChangeKeyValueForm forms ModelForm          terminal list   forms ModelMultipleChoiceField   queryset Terminal objects all          class Meta          model   ChangeKeyValue         fields      terminal list    param path    param value    scheduled time        class ChangeKeyValueAdmin admin ModelAdmin       form   ChangeKeyValueForm     list display     terminal   task list    plugin   last update time       list per page  16      def get form self  request  obj   None    kwargs           form   super ChangeKeyValueAdmin  self  get form request    kwargs          qs  filterargs   Terminal get list request          form base fields   terminal list   queryset   qs         return form

User · Answer

This is simple  and works with Django 1 4   class ClientAdminForm forms ModelForm       def   init   self   args    kwargs           super ClientAdminForm  self    init    args    kwargs            access object through self instance            self fields  base rate   queryset   Rate objects filter company self instance company   class ClientAdmin admin ModelAdmin       form   ClientAdminForm            You don t need to specify this in a form class  but can do it directly in the ModelAdmin  as Django already includes this built-in method on the ModelAdmin  from the docs    ModelAdmin formfield for foreignkey self  db field  request    kwargs       The formfield for foreignkey method on a ModelAdmin allows you to     override the default formfield for a foreign keys field  For example      to return a subset of objects for this foreign key field based on the    user      class MyModelAdmin admin ModelAdmin       def formfield for foreignkey self  db field  request    kwargs           if db field name     car               kwargs  queryset     Car objects filter owner request user          return super MyModelAdmin  self  formfield for foreignkey db field  request    kwargs    An even niftier way to do this  for example in creating a front-end admin interface that users can access  is to subclass the ModelAdmin and then alter the methods below   The net result is a user interface that ONLY shows them content that is related to them  while allowing you  a super-user  to see everything   I ve overridden four methods  the first two make it impossible for a user to delete anything  and it also removes the delete buttons from the admin site     The third override filters any query that contains a reference to  in the example  user  or  porcupine   just as an illustration      The last override filters any foreignkey field in the model to filter the choices available the same as the basic queryset     In this way  you can present an easy to manage front-facing admin site that allows users to mess with their own objects  and you don t have to remember to type in the specific ModelAdmin filters we talked about above     class FrontEndAdmin models ModelAdmin       def   init   self  model  admin site           self model   model         self opts   model  meta         self admin site   admin site         super FrontEndAdmin  self    init   model  admin site    remove  delete  buttons       def get actions self  request           actions   super FrontEndAdmin  self  get actions request          if  delete selected  in actions              del actions  delete selected           return actions   prevents delete permission      def has delete permission self  request  obj None           return False   filters objects that can be viewed on the admin site       def get queryset self  request           if request user is superuser              try                  qs   self model objects all               except AttributeError                  qs   self model  default manager get queryset               return qs          else              try                  qs   self model objects all               except AttributeError                  qs   self model  default manager get queryset                if hasattr self model     user                      return qs filter user request user              if hasattr self model     porcupine                      return qs filter porcupine request user porcupine              else                  return qs   filters choices for all foreignkey fields on the admin site       def formfield for foreignkey self  db field  request    kwargs           if request employee is superuser              return super FrontEndAdmin  self  formfield for foreignkey db field  request    kwargs           else              if hasattr db field rel to   user                    kwargs  queryset     db field rel to objects filter user request user              if hasattr db field rel to   porcupine                    kwargs  queryset     db field rel to objects filter porcupine request user porcupine              return super ModelAdminFront  self  formfield for foreignkey db field  request    kwargs

User · Answer

In addition to S Lott s answer and as becomingGuru mentioned in comments  its possible to add the queryset filters by overriding the ModelForm   init   function   This could easily apply to regular forms  it can help with reuse and keeps the view function tidy    class ClientForm forms ModelForm       def   init   self company  args   kwargs           super  ClientForm self     init    args   kwargs    populates the post         self fields  rate   queryset   Rate objects filter company company          self fields  client   queryset   Client objects filter company company       class Meta          model   Client  def addclient request  company id           the company   get object or 404 Company  id company id           if request POST              form   ClientForm the company request POST     lt -- Note the extra arg             if form is valid                    form save                   return HttpResponseRedirect the company get clients url            else              form   ClientForm the company           return render to response  addclient html                                        form   form   the company  the company     This can be useful for reuse say if you have common filters needed on many models  normally I declare an abstract Form class   E g   class UberClientForm ClientForm       class Meta          model   UberClient  def view request               form   UberClientForm company            or even extend the existing custom init class PITAClient ClientForm       def   init   company   args    args           super  PITAClient self     init   company  args   kwargs          self fields  support staff   queryset   User objects exclude user  michael     Other than that I m just restating Django blog material of which there are many good ones out there

User · Answer

To do this with a generic view  like CreateView     class AddPhotoToProject CreateView               a view where a user can associate a photo with a project             model   Connection     form class   CreateConnectionForm       def get context data self    kwargs           context   super AddPhotoToProject  self  get context data   kwargs          context  photo     self kwargs  pk           context  form   fields  project   queryset   Project objects for user self request user          return context     def form valid self  form           pobj   Photo objects get pk self kwargs  pk            obj   form save commit False          obj photo   pobj         obj save            return json     success   True           if self request is ajax                 final response   json dumps return json              return HttpResponse final response           else               messages success self request   photo was added to project                return HttpResponseRedirect reverse  MyPhotos      the most important part of that         context  form   fields  project   queryset   Project objects for user self request user      read my post here

[python] How do I filter ForeignKey choices in a Django ModelForm?

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