CODEWITHSUNDEEP
djangodjango-modelsdjango-views
Evergreenies
Evergreenies

Reputation: 45

I am working with Django, During inserting data into database i caught such error

I'm working with django, during inserting data into tables the error is generates as given below...

Error:

int() argument must be a string, a bytes-like object or a number, not 'Tbl_rule_category', How can we solve such error?

view.py

dataToRuleCtgry = Tbl_rule_category(category=category, created_by="XYZ",created_date=datetime.date.today())
dataToRuleCtgry.save()
dataToRule = Tbl_rule(rule_name=rule_name, closure=closure,category_id=Tbl_rule_category.objects.latest('category_id'), created_by="XYZ",created_date=datetime.date.today(),             updated_by="XYZ", updated_date=datetime.date.today(),             rule_type=rule_type, fk_tbl_rule_tbl_rule_category_id=Tbl_rule_category.objects.latest('category_id'))
dataToRule.save()

models.py

class Tbl_rule_category(models.Model):
    category_id = models.AutoField(primary_key=True)
    category = models.CharField(max_length=50)
    created_by = models.CharField(max_length=50)
    created_date = models.DateField(auto_now_add=True)

    def __str__(self):
        pass     # return self.category, self.created_by


class Tbl_rule(models.Model):
    rule_id = models.AutoField(primary_key=True)
    rule_name = models.CharField(max_length=50)
    closure = models.CharField(max_length=50)
    category_id = models.IntegerField()
    created_by = models.CharField(max_length=50)
    created_date = models.DateField(auto_now_add=True)
    updated_by = models.CharField(max_length=50)
    updated_date = models.DateField(auto_now=True)
    rule_type = models.CharField(max_length=50)
    fk_tbl_rule_tbl_rule_category_id = models.ForeignKey(Tbl_rule_category,on_delete=models.CASCADE, related_name='fk_tbl_rule_tbl_rule_category_id_r')

def __str__(self):
    return self.rule_name, self.closure, self.created_by, self.updated_by, self.rule_type

Upvotes: 0

Views: 103

Answers (2)

Aiky30
Aiky30

Reputation: 880

The error is occurring because the following is trying to add an object into an integer field: category_id=Tbl_rule_category.objects.latest('category_id')

You could just add: category_id=dataToRuleCtgry.get('category_id') or category_id=dataToRuleCtgry.category_id which will solve the error.

You also don't need to add: created_date=datetime.date.today() because your model defines auto_now=true.

As mentioned you should also amend the def __str__(self): to return a string. https://docs.djangoproject.com/en/2.0/ref/models/instances/#django.db.models.Model.str

Alternatively

You could just add the object link directly to your foreign key for the category model.fk_tbl_rule_tbl_rule_category_id=dataToRuleCtgry. You would no longer need the integer field category_id.

It would be better practice to use the model field name category_id instead of fk_tbl_rule_tbl_rule_category_id. This would mean deleting category_id and then rename fk_tbl_rule_tbl_rule_category_id to category_id.

Upvotes: 2

Burhan Khalid
Burhan Khalid

Reputation: 174728

In Django, the ORM takes care of the basic database details for you; which means in your code you really don't have to worry about individual row ids for maintaining foreign key relationships.

In fact, Django automatically assigns primary keys to all your objects so you should concentrate on fields that are relevant to your application.

You also don't have to worry about naming fields in the database, again Django will take care of that for you - you should create objects that have fields that are meaningful to users (that includes you as a programmer of the system) and not designed for databases.

Each Django model class represents a object in your system. So you should name the classes as you would name the objects. User and not tbl_user. The best practice is to use singular names. Django already knows how to create plural names, so if you create a model class User, django will automatically display Users wherever it makes sense. You can, of course, customize this behavior.

Here is how you should create your models (we will define __str__ later):

class RuleCategory(models.Model):
    name = models.CharField(max_length=50)
    created_by = models.CharField(max_length=50)
    created_date = models.DateField(auto_now_add=True)

class Rule(models.Model):
    name = models.CharField(max_length=50)
    closure = models.CharField(max_length=50)
    created_by = models.CharField(max_length=50)
    created_date = models.DateField(auto_now_add=True)
    updated_by = models.CharField(max_length=50)
    updated_date = models.DateField(auto_now=True)
    rule_type = models.CharField(max_length=50)
    category = models.ForeignKey(RuleCategory,on_delete=models.CASCADE)

Django will automatically create any primary or foreign key fields, and any intermediary tables required to manage the relationship between the two models.

Now, to add some records:

new_category = RuleCategory(name='My Category', created_by='XYZ')
new_category.save()

# Another way to set values
new_rule = Rule()
new_rule.name = 'Sample Rule'
new_rule.closure = closure
new_rule.created_by = 'XYZ'
new_rule.updated_by = 'XYZ'
new_rule.rule_type = rule_type
new_rule.category = new_category
new_rule.save()

Note this line new_rule.category = new_category - this is how we link two objects. Django knows that the primary key should go in the table and will take care of that automatically.

The final item is customizing the models by creating your own __str__ method - this should return some meaningful string that is meant for humans.

class RuleCategory(models.Model):
    name = models.CharField(max_length=50)
    created_by = models.CharField(max_length=50)
    created_date = models.DateField(auto_now_add=True)

    def __str__(self):
        return '{}'.format(self.name)

class Rule(models.Model):
    name = models.CharField(max_length=50)
    closure = models.CharField(max_length=50)
    created_by = models.CharField(max_length=50)
    created_date = models.DateField(auto_now_add=True)
    updated_by = models.CharField(max_length=50)
    updated_date = models.DateField(auto_now=True)
    rule_type = models.CharField(max_length=50)
    category = models.ForeignKey(RuleCategory,on_delete=models.CASCADE)

    def __str__(self):
        return '{} for category {}'.format(self.name, self.category)

If you notice something, I just put self.category in the __str__ for the Rule model. This is because we have already defined a __str__ for the RuleCategory model, which just returns the category name; so now when we print our Rule we created, we will get Sample Rule for category My Category as a result.

Upvotes: -1

Related Questions