如何使admin.TabularInline中的某个字段成为条件字段？

from django.contrib import admin
from django.forms import widgets

class MyInline(admin.TabularInline):
    model = MyModel

    def get_formset(self, request, obj=None, **kwargs):
        formset = super().get_formset(request, obj, **kwargs)
        
        for form in formset.forms:
            # 设置字段条件，这里以一个名为field_name的字段为例
            if form.instance.field_name == '条件值':
                form.fields['field_name'].widget = widgets.TextInput(attrs={'readonly': 'readonly'})
        
        return formset

from django.contrib import admin
from django.forms import widgets

class MyInline(admin.TabularInline):
    model = MyModel

    def get_fields(self, request, obj=None):
        fields = super().get_fields(request, obj)
        
        # 设置字段条件，这里以一个名为field_name的字段为例
        for field_name in fields:
            if field_name == 'field_name':
                fields[field_name].widget = widgets.TextInput(attrs={'readonly': 'readonly'})
        
        return fields