CODEWITHSUNDEEP
pythondjango
Afzal S.H.
Afzal S.H.

Reputation: 1084

Django ListField with add and remove

The below link specifies how to create a list-field in Django.

How to create list field in django

My question; how to add, remove items to this field? if in case that's possible. I want to be able to add to and remove from this field of a Model's instance afterwards. If not possible please someone suggest me an alternative.

Upvotes: 2

Views: 2969

Answers (2)

WeizhongTu
WeizhongTu

Reputation: 6414

in ListField:

to_python function is used to convert database string to python object(here is list) get_prep_value is used to handle python object to string(to store into database next step). when you call your obj.listfield, such as a.list, you'll get a python list, so you could use a.list.append(val), a.list.insert(0, val) method to operate, and at last call a.save(), listfield will do the conversion for you between database and python.

class Dummy(models.Model):
    mylist = ListField()

    def insert_to_mylist(self, index, value):
        self.mylist.insert(index, value)
        #self.save()
    def remove_from_mylist(self, value):
        self.mylist.remove(value)
        #self.save()

for example:

d = Dummy()
d.mylist.insert(0, 'tu')
d.save()

d.mylist.remove('tu')
d.save()

d.insert_to_mylist(0, "tu")
d.save()

d.remove_from_mylist('tu')
d.save()

if you want to insert or remove without .save(), just add .save() to insert_to_mylist and remove_from_mylist function.

ListField is just used to conversion between database and python, so add a remove or insert to it may be difficult. But you can do it in your Model, if many Models need to use this method, just write an abstract model.

Upvotes: 4

Aswin Murugesh
Aswin Murugesh

Reputation: 11070

My way of storing lists in models is by converting them to a string and storing them as TextField.

Upvotes: 1

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