Changes between Initial Version and Version 2 of Ticket #34333


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Timestamp:
Feb 13, 2023, 3:09:56 PM (3 years ago)
Author:
Raphael Beekmann
Comment:

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  • Ticket #34333 – Description

    initial v2  
    11Hello,
    22
    3 I have a model, already created through previous migrations, and in a new migration I added a new field with a UniqueConstraint.
    4 The model looks like this (the new field is 'type') :
     3I have a model, already created through previous migrations, and in a new migration I added a new field with an UniqueConstraint. The migrations script try to create the constraint first and then the new field, resulting an error :
     4
     5{{{
     6django.core.exceptions.FieldDoesNotExist: NewModel has no field named 'category'
     7}}}
     8
     9
     10To reproduce the bug :
     11
     121. Create a project with two models linked together with a One-to-Many relation and an unique constraint :
     13
     14{{{
     15class Type(models.Model):
     16    name = models.CharField(max_length=10)
     17
     18
     19class Model(models.Model):
     20    name = models.CharField(max_length=10)
     21    type = models.ForeignKey(Type, on_delete=models.SET_NULL, null=True)
     22    date = models.DateField(auto_now=True)
     23
     24    class Meta:
     25        constraints = (
     26            models.UniqueConstraint(fields=('date', 'type'), name='unique_type_for_date'),
     27        )
     28}}}
     29
     302. Create a migration file with `manage.py makemigrations`
     31
     323. Add a new model with another One-to-Many relation and unique constraint. The models looks like this :
    533
    634
    735{{{
     36class Type(models.Model):
     37    name = models.CharField(max_length=10)
     38
     39
     40class Category(models.Model):
     41    name = models.CharField(max_length=10)
     42
     43
    844class Model(models.Model):
    9     name = models.CharField()
    10     date = models.DateField()
    11     type = models.ForeignKey(OtherModel)
     45    name = models.CharField(max_length=10)
     46    type = models.ForeignKey(Type, on_delete=models.SET_NULL, null=True)
     47    category = models.ForeignKey(Category, on_delete=models.SET_NULL, null=True)
     48    date = models.DateField(auto_now=True)
    1249
    1350    class Meta:
    1451        constraints = (
    15             models.UniqueConstraint(fields=('date', 'type'), name='unique_date_for_type'),
     52            models.UniqueConstraint(fields=('date', 'type'), name='unique_type_for_date'),
     53            models.UniqueConstraint(fields=('date', 'category'), name='unique_category_for_date'),
    1654        )
    1755}}}
    1856
    19 When I run the makemigrations script it adds first the constraint and then the new field. That occurs an error when executing the migration :
     57
     584. Create a new migration file. The order of the migration's steps are incorrect and the migration crash :
     59
    2060
    2161{{{
    22 django.core.exceptions.FieldDoesNotExist: DailyTask has no field named 'type'
     62class Migration(migrations.Migration):
     63
     64    dependencies = [
     65        ('app', '0001_initial'),
     66    ]
     67
     68    operations = [
     69        migrations.CreateModel(
     70            name='Category',
     71            fields=[
     72                ('id', models.BigAutoField(auto_created=True, primary_key=True, serialize=False, verbose_name='ID')),
     73                ('name', models.CharField(max_length=10)),
     74            ],
     75        ),
     76        migrations.AddConstraint(
     77            model_name='model',
     78            constraint=models.UniqueConstraint(fields=('date', 'category'), name='unique_category_for_date'),
     79        ),
     80        migrations.AddField(
     81            model_name='model',
     82            name='category',
     83            field=models.ForeignKey(null=True, on_delete=django.db.models.deletion.SET_NULL, to='app.category'),
     84        ),
     85    ]
    2386}}}
    2487
    25 I have to manually move the adds of the constraint before the adds of the new field in the migration file to make it work.
    26 
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