'Options' object has no attribute 'get_all_field_names'
<p>In my <code>django-admin</code>, I am trying to make a <code>model</code> non-editable. </p>

<p>So, I am <code>overriding</code> a method <code>get_readonly_fields</code> of <code>admin.ModelAdmin</code>. </p>

<p><code>Here is my Code</code></p>

<pre><code>@admin.register(SMSTemplate)
class SMSTemplateAdmin(admin.ModelAdmin):
    list_display=['title', 'json', 'note']
       formfield_overrides = {
       JSONField: {'widget': PrettyJSONWidget }
    }

    def has_delete_permission(self, request, obj=None):
        return False

    def get_readonly_fields(self, request, obj=None):
        return self.model._meta.get_all_field_names()
</code></pre>

<p>But I am facing an error. I am pasting the error here. </p>

<pre><code>'Options' object has no attribute 'get_all_field_names'
</code></pre>

<p>Any Idea why ?</p>