# Models -Type errors, and Primary keys

**URL:** <https://forum.djangoproject.com/t/models-type-errors-and-primary-keys/17837>\
**Category:** Using the ORM\
**Created:** [December 26, 2022, 6:59pm UTC](https://forum.djangoproject.com/t/models-type-errors-and-primary-keys/17837 "2022-12-26T18:59:13Z")\
**Posts on this page:** 8\
**Page:** 1

<div class="post-metadata">

**Author:** ![zuri](https://sea2.discourse-cdn.com/flex026/user_avatar/forum.djangoproject.com/zuri/32/10925_2.png) [@zuri](https://forum.djangoproject.com/u/zuri)\
**Post date:** [December 26, 2022, 6:59pm UTC](https://forum.djangoproject.com/t/models-type-errors-and-primary-keys/17837/1 "2022-12-26T18:59:13Z")

</div>

Hello, I’m new to Django, and models.

Is there any reason why a Model would throw an error without using a custom primary key(primary\_key=True)

Without using the custom primary key, in any module I create, I get the error below.

Type Error: Field ‘id’ expected a number but got ‘author’  
Type Error: Field ‘id’ expected a number but got ‘name’

my code:

from django.db import models

class Plan(models.Model):  
author = models.CharField(max\_length=64)  
the\_plan = models.CharField(max\_length=64)

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

```

class Weapon(models.Model):  
name = models.CharField(max\_length=64)  
type = models.CharField(max\_length=64)

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

```

Thanks for any help!

---

<div class="post-metadata">

**Author:** ![KenWhitesell](https://sea2.discourse-cdn.com/flex026/user_avatar/forum.djangoproject.com/kenwhitesell/32/280_2.png) [@KenWhitesell](https://forum.djangoproject.com/u/KenWhitesell)\
**Post date:** [December 26, 2022, 8:36pm UTC](https://forum.djangoproject.com/t/models-type-errors-and-primary-keys/17837/2 "2022-12-26T20:36:17Z")

</div>

**All** Django models have a primary key. See [Model field reference | Django documentation | Django](https://docs.djangoproject.com/en/4.1/ref/models/fields/#django.db.models.Field.primary_key) and [Models | Django documentation | Django](https://docs.djangoproject.com/en/4.1/topics/db/models/#automatic-primary-key-fields).

---

<div class="post-metadata">

**Author:** ![Artur](https://sea2.discourse-cdn.com/flex026/user_avatar/forum.djangoproject.com/artur/32/11321_2.png) [@Artur](https://forum.djangoproject.com/u/Artur)\
**Post date:** [December 28, 2022, 7:00pm UTC](https://forum.djangoproject.com/t/models-type-errors-and-primary-keys/17837/3 "2022-12-28T19:00:11Z")

</div>

I’m new to Django as well but have succesfully used models that did not have a custom primary key. In these situations Django creates an id pk automatically. When are you receiving these errors?

---

<div class="post-metadata">

**Author:** ![zuri](https://sea2.discourse-cdn.com/flex026/user_avatar/forum.djangoproject.com/zuri/32/10925_2.png) [@zuri](https://forum.djangoproject.com/u/zuri)\
**Post date:** [December 28, 2022, 7:56pm UTC](https://forum.djangoproject.com/t/models-type-errors-and-primary-keys/17837/4 "2022-12-28T19:56:25Z")

</div>

I had a few practice projects with several baseline apps installed. Each had a few models created, all without a custom primary key. Everything was working, I went back in a day later, and I could not save the models in the ORM.

I kept getting this error below:

Type Error: Field ‘id’ expected a number but got ‘first\_name’

Adding a custom primary key to each model stopped the errors, and I was able to save the model and make migrations. Without the custom, primary key things would break, and the Type Error returned.

I created some new projects, and models without the custom key, and all function properly.  
I’m not sure what happened. Maybe the python cache files were causing a conflict?

Anyways, it was all just dummy data, but a strange event nonetheless in this learning process.

---

<div class="post-metadata">

**Author:** ![KenWhitesell](https://sea2.discourse-cdn.com/flex026/user_avatar/forum.djangoproject.com/kenwhitesell/32/280_2.png) [@KenWhitesell](https://forum.djangoproject.com/u/KenWhitesell)\
**Post date:** [December 28, 2022, 8:02pm UTC](https://forum.djangoproject.com/t/models-type-errors-and-primary-keys/17837/5 "2022-12-28T20:02:53Z")

</div>

It would be of more help to us if you posted the _complete_ traceback of the error, along with the code throwing it.

---

<div class="post-metadata">

**Author:** ![zuri](https://sea2.discourse-cdn.com/flex026/user_avatar/forum.djangoproject.com/zuri/32/10925_2.png) [@zuri](https://forum.djangoproject.com/u/zuri)\
**Post date:** [December 29, 2022, 12:23am UTC](https://forum.djangoproject.com/t/models-type-errors-and-primary-keys/17837/6 "2022-12-29T00:23:57Z")

</div>

This simple model is an example

```auto
from django.db import models

# Create your models here.

class Bonsai(models.Model):
    
    # remove (s) from table name in Django admin
    class Meta:
        verbose_name_plural = "Bonsai"    

    name = models.CharField(max_length=64)
    age = models.IntegerField()
    placement = models.CharField(max_length=64)

    def __str__ (self):
        return f"{self.name} ({self.age} years)"

```

_o = Bonsai(“Oak”, 44,“Outdoor”)_  
_o.save()_

**Traceback…**

```auto
Traceback (most recent call last):
  File "<console>", line 1, in <module>
  File "C:\Users\Studio\Desktop\CodeMedia\env\Lib\site-packages\django\db\models\base.py", line 812, in save
    self.save_base(
  File "C:\Users\Studio\Desktop\CodeMedia\env\Lib\site-packages\django\db\models\base.py", line 863, in save_base
    updated = self._save_table(
              ^^^^^^^^^^^^^^^^^
  File "C:\Users\Studio\Desktop\CodeMedia\env\Lib\site-packages\django\db\models\base.py", line 976, in _save_table
    updated = self._do_update(
              ^^^^^^^^^^^^^^^^
  File "C:\Users\Studio\Desktop\CodeMedia\env\Lib\site-packages\django\db\models\base.py", line 1019, in _do_update
    filtered = base_qs.filter(pk=pk_val)
               ^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\Studio\Desktop\CodeMedia\env\Lib\site-packages\django\db\models\query.py", line 1420, in filter
    return self._filter_or_exclude(False, args, kwargs)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\Studio\Desktop\CodeMedia\env\Lib\site-packages\django\db\models\query.py", line 1438, in _filter_or_exclude
    clone._filter_or_exclude_inplace(negate, args, kwargs)
  File "C:\Users\Studio\Desktop\CodeMedia\env\Lib\site-packages\django\db\models\query.py", line 1445, in _filter_or_exclude_inplace
    self._query.add_q(Q(*args, **kwargs))
  File "C:\Users\Studio\Desktop\CodeMedia\env\Lib\site-packages\django\db\models\sql\query.py", line 1532, in add_q
    clause, _ = self._add_q(q_object, self.used_aliases)
                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\Studio\Desktop\CodeMedia\env\Lib\site-packages\django\db\models\sql\query.py", line 1562, in _add_q
    child_clause, needed_inner = self.build_filter(
                                 ^^^^^^^^^^^^^^^^^^
  File "C:\Users\Studio\Desktop\CodeMedia\env\Lib\site-packages\django\db\models\sql\query.py", line 1478, in build_filter
    condition = self.build_lookup(lookups, col, value)
                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\Studio\Desktop\CodeMedia\env\Lib\site-packages\django\db\models\sql\query.py", line 1303, in build_lookup
    lookup = lookup_class(lhs, rhs)
             ^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\Studio\Desktop\CodeMedia\env\Lib\site-packages\django\db\models\lookups.py", line 27, in __init__
    self.rhs = self.get_prep_lookup()
               ^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\Studio\Desktop\CodeMedia\env\Lib\site-packages\django\db\models\lookups.py", line 341, in get_prep_lookup
    return super().get_prep_lookup()
           ^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\Studio\Desktop\CodeMedia\env\Lib\site-packages\django\db\models\lookups.py", line 85, in get_prep_lookup
    return self.lhs.output_field.get_prep_value(self.rhs)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\Studio\Desktop\CodeMedia\env\Lib\site-packages\django\db\models\fields\ __init__.py", line 2020, in get_prep_value
    raise e. __class__ (
ValueError: Field 'id' expected a number but got 'Oak'.

```

---

<div class="post-metadata">

**Author:** ![KenWhitesell](https://sea2.discourse-cdn.com/flex026/user_avatar/forum.djangoproject.com/kenwhitesell/32/280_2.png) [@KenWhitesell](https://forum.djangoproject.com/u/KenWhitesell)\
**Post date:** [December 29, 2022, 1:47am UTC](https://forum.djangoproject.com/t/models-type-errors-and-primary-keys/17837/7 "2022-12-29T01:47:24Z")

</div>

One issue is that you’re not using the model correctly.

From the docs at [Making queries | Django documentation | Django](https://docs.djangoproject.com/en/4.1/topics/db/queries/#creating-objects)

> To create an object, instantiate it **using keyword arguments** to the model class, then call [`save()`](https://docs.djangoproject.com/en/4.1/ref/models/instances/#django.db.models.Model.save) to save it to the database.

It’s not considered “proper” to try to create the instance using positional arguments.

I don’t have an explanation as to why it works in some cases - I’d just chalk that up as being “one of those things”.

---

<div class="post-metadata">

**Author:** ![zuri](https://sea2.discourse-cdn.com/flex026/user_avatar/forum.djangoproject.com/zuri/32/10925_2.png) [@zuri](https://forum.djangoproject.com/u/zuri)\
**Post date:** [December 29, 2022, 5:31am UTC](https://forum.djangoproject.com/t/models-type-errors-and-primary-keys/17837/8 "2022-12-29T05:31:31Z")

</div>

That solved it.

Thanks for the solution Ken!

Also, thanks for the suggestions @Artur!