How to show different inlines depending of current object field value

Question

Given a model named MainModel and a RelatedModel, where the later has a ForeignKey field to MainModel:

class          


        

Answer 1

Here is a piece of code I wrote when I was faced with the same problem. It is a bit brute force style, I guess, but is very agile and should suit all cases.

class MyModelAdmin(admin.ModelAdmin):
    def __init__(self, *args, **kwargs):
        super(MyModelAdmin, self).__init__(*args, **kwargs)
        self.inline_instances_hash = {}
        for inline_class in self.inlines:
            for inline_instance in self.inline_instances:
                if isinstance(inline_instance, inline_class):
                    break
            self.inline_instances_hash[inline_class] = inline_instance

    def get_inline_instance(self, inline_class):
        return self.inline_instances_hash[inline_class]

    def get_form(self, request, obj=None, **kwargs):
        if obj:
            self.inline_instances = []
            if self.CONDITION:
                self.inline_instances.append(self.get_inline_instance(
                    THE_INLINE_CLASS_I_WANT))
            #...
        else:
            self.inline_instances = self.inline_instances_hash.values()