how to save many to many field using django custom forms - django

Question

how can i save many courses to the student table .I want to keep my design like this.This code is not saving the many to many field(courses) through AddStudentForm.It returns an error with courses variable.If i used CharField instead of ManyToManyField in models for courses then the code works perfectly,but when i use ManyToManyField then it is not working.
it throws courses when i used form.errors .If i didn't use form.errors then it doesn't give any error neither saves the data.
how can i save many courses to the student table .I want to keep my design like this.This code is not saving the many to many field(courses) through AddStudentForm.It returns an error with courses variable.
models.py
class Course(models.Model):
title = models.CharField(max_length=250)
price = models.IntegerField(default=0)
duration = models.CharField(max_length=50)
def __str__(self):
return self.title
class Student(models.Model):
name = models.CharField(max_length=100)
courses = models.ManyToManyField(Course)
email = models.EmailField()
image = models.ImageField(upload_to='Students',blank=True)
def __str__(self):
return self.name
forms.py
class AddStudentForm(forms.ModelForm):
# courses = forms.ModelMultipleChoiceField(widget=forms.CheckboxSelectMultiple, queryset=Course.objects.all())
class Meta:
model = Student
fields = ['name','courses','email','image']
def __init__(self, *args, **kwargs):
super(AddStudentForm, self).__init__(*args, **kwargs)
self.fields["courses"].widget = CheckboxSelectMultiple()
self.fields["courses"].queryset = Course.objects.all()
views.py
def addstudent(request):
courses = Course.objects.all()
if request.method == 'POST':
form = AddStudentForm(request.POST,request.FILES)
if form.is_valid():
student = form.save(commit=False)
course = form.cleaned_data['courses']
student.courses = course
student.save()
# student.courses.add(course)
# student.save_m2m()
# student.courses.set(course) # this method also didn't helped me
messages.success(request, 'student with name {} added.'.format(student.name))
return redirect('students:add_student')
else:
# messages.error(request,'Error in form.Try again')
return HttpResponse(form.errors) # this block is called and returns courses
else:
form = AddStudentForm()
return render(request,'students/add_student.html',{'form':form,'courses':courses})
add_student.html
<form action="{% url 'students:add_student' %}"
method="post"
enctype="multipart/form-data">
{% csrf_token %}
<div class="form-group">
<h5>Full Name <span class="text-danger">*</span>
</h5>
<div class="controls">
<input type="text" name="name" class="form-
control" > </div>
</div>
<div class="form-group">
<h5>Courses<span class="text-danger">*</span>
</h5>
<div class="controls">
{% for course in courses %}
<input name ="courses" type="checkbox" id="course-
{{course.id}}" value="{{course.title}}">
<label for="course-{{course.id}}">{{course.title}}
</label>
{% endfor %} # i think the problem is here.
</div>
</div>
<div class="form-group">
<h5>Email <span class="text-danger">*</span></h5>
<div class="controls">
<input type="text" name="email" class="form-
control" required> </div>
</div>
</div>
<div class="form-group">
<h5>Image <span class="text-danger">*</span></h5>
<div class="controls">
<input type="file" name="image" class="form-control" > </div>
</div>
<div class="text-xs-right">
<button type="submit" class="btn btn-info">Add</button>
</div>
</form>

Answer 1

You need to save first before you can assign m2m, the system needs the primary key of the Student model before it can insert into the m2m table.
if form.is_valid():
student = form.save(commit=False)
course = form.cleaned_data['courses']
student.save()
# this will save by itself
student.courses.set(course)