django save form - overwrite old row

Question

I have a form to add new data to my database, but this form overwrites the existing data in my table. I want to add a new tuple and keep old tuples in my database's table

forms.py

class StudentForm(forms.ModelForm):
    class Meta:
        model = student
        fields = ('First_Name', 'Last_Name', 'Birthday', 'Phone', 'Mobile', 'STNO',
          'Father_Name', 'Father_Job', 'Father_Phone', 'ID_Code',
          'National_ID', 'Address', 'Study_Field', 'Probation')

views.py

def add_student(request):
    if request.method == "POST":
        form = StudentForm(request.POST)
        if form.is_valid():
            new_student = form.save(commit=True)
            new_student.author = request.user
            new_student.save()
            return redirect('../')
    else:
        form = StudentForm()
    return render(request, 'school_manager/students/new_student.html', {'form': form})

models.py

class student(models.Model):
    id = models.IntegerField(default=1,null=False,primary_key=True)
    First_Name = models.CharField("First Name ", max_length=100,null=True)
    Last_Name = models.CharField("Last Name ",max_length=100,null=True)
    Birthday = models.CharField("Birthday ",max_length=10,null=True)
    Phone = models.CharField("Phone ",max_length=20,null=True)
    Mobile = models.CharField("Mobile ",max_length=20,null=True)
    STNO = models.CharField("STNO ",max_length=10,null=True)
    Father_Name = models.CharField("Father Name ",max_length=100,null=True)
    Father_Job = models.CharField("Father Job ",max_length=100,null=True)
    Father_Phone = models.CharField("Father Phone ",max_length=20,null=True)
    ID_Code = models.CharField("ID Code ",max_length=10,null=True)
    National_ID = models.CharField("National ID ",max_length=10,null=True)
    Address = models.CharField("Address ",max_length=200,null=True)
    Study_Field = models.CharField("Study Field ",max_length=100,null=True)
    Probation = models.BooleanField("Probation ",default=True)
    def __STR__ (self):
        return self.STNO

What table? Do you mean you don't want to update new_student and instead create a new one? — Sayse
– Sayse, Commented Dec 11, 2015 at 9:30
database table ..... yes i want to create but this code update existing row @Sayse — Arash Hatami
– Arash Hatami, Commented Dec 11, 2015 at 9:42
Possible duplicate of How do I clone a Django model instance object and save it to the database? — Sayse
– Sayse, Commented Dec 11, 2015 at 9:48
i just want add a new table row :( . for example a blog ..... add a new post with title and content when click "Add" button each time @Sayse — Arash Hatami
– Arash Hatami, Commented Dec 11, 2015 at 9:54

dani herrera · Accepted Answer · 2015-12-11 10:00:45Z

4

The model was relevant. Look this:

class student(models.Model):
    id = models.IntegerField(default=1,null=False,primary_key=True)

You are always creating student number 1.

You should to set a new id by hand for each student:

def add_student(request):
    if request.method == "POST":
        form = StudentForm(request.POST)
        if form.is_valid():
            new_student = form.save(commit=False)
            id = a_function_to_take_another_id_for_a_student()
            new_student.id = id
            new_student = form.save(commit=True)
            new_student.author = request.user

Another approach is to can change type id to auto increment field:

id = models.AutoField(primary_key=True)

edited Dec 11, 2015 at 10:00

answered Dec 11, 2015 at 9:58

dani herrera

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1 Comment

Sayse Over a year ago

Good spot, I rescind my comment.. (The model shouldn't have been relevant :P)

GwynBleidD · Accepted Answer · 2015-12-11 10:01:35Z

2

Problem is in your model. You've explictly set ID field, as below:

    id = models.IntegerField(default=1,null=False,primary_key=True)

But you're not setting it in form. That way django will each time create row with ID = 1 (because that's default value).

When you're creating field with ID that already exists in database, django will update existing field because it can't create new (there can't be more than one field with same primary key).

You should change type of ID to AutoField or remove it's definition, django will then create default ID field that will be an AutoField.

answered Dec 11, 2015 at 10:01

GwynBleidD

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2 Comments

Arash Hatami Over a year ago

i used that "default=1" in the past for some problems and i forget remove that .... thank you ... problem solved

dani herrera Over a year ago

@ArashHatami, you know how to say thanks: vote up their post ! Every upvote is an implicit "thank you".

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