"Please correct the error below." when saving edit model form with inline formset and space at the end of primary key value

[Alex Uralov]

I have an Attribute instance in DB with name 'Motor type ' (space in the end). Also, I have AttributeValueInlineAdmin as inline for AttributeAdmin. When I try to change field display_name for that instance in Django admin I get an error "Please correct the error below." with no errors shown.

The reason for that error is the space at the end of the primary key.

[Alex Uralov]

Models and admin classes

[Tim Graham]

I can't reproduce this given the models and admin you provided. Which version of Django are you using? Starting ​in Django 1.9:

CharField now strips input of leading and trailing whitespace by default. This can be disabled by setting the new strip argument to False.

The behavior I see when editing an Attribute whose name contains a trailing space is that a new instance is created because primary keys aren't editable as described in #2259.

[Alex Uralov]

Replying to Tim Graham:

I can't reproduce this given the models and admin you provided. Which version of Django are you using? Starting ​in Django 1.9:

CharField now strips input of leading and trailing whitespace by default. This can be disabled by setting the new strip argument to False.

The behavior I see when editing an Attribute whose name contains a trailing space is that a new instance is created because primary keys aren't editable as described in #2259.

I use Django==2.0.8. Could you reproduce this by steps:
1) Create a new Attribute item without spaces. For example 'test'
2) Change the name (primary key) of the attribute via db query. UPDATE "public"."MODULE_attribute" SET "name" = 'test ' WHERE "name" = 'test'
3) Open Django admin panel and try to append any AttributeValue to 'test ' attribute.
4) I get the error message "Please correct the error below."

[Tim Graham]

Yes, I can reproduce with those steps. Thanks. Inspecting the errors manually, I see [{'attribute': ['The inline value did not match the parent instance.']}]. I think the root cause is that the trailing space is stripped in the parent instance but not for the child instance. I don't think this is a bug in Django but it could be considered a duplicate of #2259 in that the primary key probably shouldn't be editable in the first place. I think you could fix that using ModelAdmin.readonly_fields.

[Alex Uralov]

Thank you for the advice!