make django model field read only or disable in admin while saving the object first time

Question

I want to disable the few fields from model in django admin while saving initially.

"<input type="text" id="disabledTextInput" class="form-control" placeholder="Disabled input">"

like this.

My model is:

class Blogmodel(models.Model):
    tag = models.ForeignKey(Tag)
    headline = models.CharField(max_length=255)
    image=models.ImageField(upload_to=get_photo_storage_path, null=True, blank=False)
    body_text = models.TextField()
    pub_date = models.DateField()
    authors = models.ForeignKey(Author)
    n_comments = models.IntegerField()

i want to disable the "headline" and "n_comments". i tried it in admin.py file, but its not disabling the fields on initial saving. But for editing the fields its working, it making the fields read only.

in admin.py

class ItemAdmin(admin.ModelAdmin):
    exclude=("headline ",)
    def get_readonly_fields(self, request, obj=None):
        if obj:
            return ['headline']
        else:
            return []

Headling getting disabled but for edit only. i want to disable it at the time of object creation. i.e. first save. can anyone guide me for this?

Answer 1

There is no need to override get_readonly_fields. Simplest solution would be:

class ItemAdmin(admin.ModelAdmin):
    exclude=("headline ",)
    readonly_fields=('headline', )

When using readonly_fields you can't override get_readonly_fields, because default implementation reads readonly_fields variable. So overriding it only if you have to have some logic on deciding which field should be read-only at time.