Django ForeignKey("x") field must be a "x" instance on update

Django version 4.2.9

I try to fix this :
Cannot assign "(‘customer’,)": "Project.customer" must be a "Customer" instance.

I have 2 classes, Project and Customer.

class Customer(models.Model):
    customer_name = models.CharField(max_length=50)
    string = models.CharField(max_length=50)

    def __str__(self):
        return f"{self.customer_name}"

class Project(models.Model):
    project_name = models.TextField()
    project_code = models.CharField(max_length=50,null=True,blank=True)
    project_scope = models.CharField(max_length=200,blank=True,null=True)
    customer = models.ForeignKey("Customer", on_delete=models.DO_NOTHING)
    project_type = models.ForeignKey("ProjectType", on_delete=models.DO_NOTHING)
    is_rd = models.BooleanField(null=True,blank=True)
    #TARIHLER
    request_date = models.DateField(auto_now=False, auto_now_add=False)
    confirmation_date = models.DateField(auto_now=False, auto_now_add=False, null=True,blank=True)
    estimated_finish_date = models.DateField(auto_now=False, auto_now_add=False)
    project_finish_date = models.DateField(auto_now=False, auto_now_add=False, null=True,blank=True,default="01/01/1970")
    update_date = models.DateField(auto_now=False, auto_now_add=False,null=True, blank=True,default="01/01/1970")
    start_date = models.DateField(auto_now=False, auto_now_add=False,null=True, blank=True,default="01/01/1970")
    #TARIHLER
    update_count = models.IntegerField(null=True,blank=True)
    estimated_cost = models.IntegerField()
    actual_cost = models.IntegerField(null=True,blank=True)

    is_active = models.BooleanField(default=False)
    project_leader_id = models.ForeignKey("account.MamurUser", on_delete=models.DO_NOTHING)
    bill = models.BooleanField()
    patent = models.BooleanField(default=False,blank=True)
    market = models.BooleanField(default=False,blank=True)
    is_confirmed = models.BooleanField(default=False,blank=True)
    is_pmo_confirmed = models.BooleanField(default=False,blank=True)

This is my views.py:

def edit_project(request):
    context={
            "projects" : Project.objects.filter(is_confirmed=False)
    }
    if request.method == "GET":
        return render(request,'pyka/project-edit.html',context)
    else:

        post = request.POST
        project_id = post['project_id']

        project = Project.objects.get(id=project_id)
        update_count = project.update_count
        update_count += 1
        valid = True # değişecek
        error = None
        
        now = datetime.date.today()
        project_name = post['project-name']
        customer = Customer.objects.get(id=post['customer'])
        type = ProjectType.objects.get(id=post['type'])
        project_scope = post['project-scope']
        project_budget = post['project-budget']
        user_data = post['userData']
        user_data = json.loads(user_data)
        start_date = post['start-date']
        end_date = post['end-date']
        patent = post.get('patent', False)
        market = post.get('market', False)
        # VALIDATION
        if valid:

            pd = ProjectDetail.objects.filter(project_id=project_id)

            for d in pd:
                if d.project_role is not Role.objects.get(id=2):
                    d.delete()

            project.project_name = project_name,
            project.project_scope = project_scope,
            project.customer = customer,
            project.project_type = type,
            project.estimated_finish_date = end_date,
            project.update_date = now,
            project.update_count = update_count,
            project.start_date = start_date,
            project.estimated_cost = project_budget,
            project.patent = patent,
            project.market = market,
            
            project.save()


            users = MamurUser.objects.all()
            pmo = Role.objects.filter(id=4).first()
            # Tüm PMO Userları projeye dahil et
            for user in users:
                if user.role_id == pmo:
                    ProjectDetail.objects.create(
                    user_id = MamurUser.objects.filter(id=user.id).first(),
                    project_id = project,
                    project_role = pmo,
                    )
        
            ProjectDetail.objects.create(
                    user_id = MamurUser.objects.filter(id=request.user.id).first(),
                    project_id = project,
                    project_role = Role.objects.filter(id=2).first(),
                )

            for data in user_data:
                user_id = data.get('user')
                ProjectDetail.objects.create(
                    user_id = MamurUser.objects.filter(id=user_id).first(),
                    project_id = project,
                    project_role = Role.objects.filter(id=1).first(),
                )
            context += {"success","Başarıyla Güncellendi"}
        return render(request,'pyka/project-edit.html',context)

and throws this :

Internal Server Error: /edit-project
raise ValueError(
ValueError: Cannot assign "(‘customer’,)": "Project.customer" must be a "Customer" instance.

I try to update Project instance, but Django throws exception