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I have created a sample Django application with multiple models within it and populated data.

Now, I need to add a new column to one of the models?

Here are my concerns?

  1. What will happen if I do syncdb after adding a column to the model , will it just alter the table and add the new column?
  2. Or will it create a new table after deleting all the columns?

Is there any better way to tackle this issue?

user1050619
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3 Answers3

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syncdb does not work for altering database tables. Here is the documentation (Readup on : Syncdb will not alter existing tables)

A clean way to achieve this would be to use a 3rd party tool such as django south which would handle the migrations (Handle the alter table scripts in your case) for you.

Here is a step by step tutorial on south, and here is the official documentation on south

karthikr
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    South has emerged as the dominant tool for managing this, but you can also modify your schema to add the column directly. Something like `alter table myapp_mymodel add column mycolumn integer;` - or whatever depending on your data type and database back end. This is much less maintainable, so it's not the preferred approach, but if you just need a small modification it's an option. – Peter DeGlopper Aug 07 '13 at 16:46
  • Agreed. Especially when the project is in the early stages of development, and you are still developing it locally, it is a good option – karthikr Aug 07 '13 at 16:49
  • If you do end up making changes by hand, `python manage.py sql ` will output the sql Django would use if it were creating the tables for the app. This is useful for keeping your column types consistent and more importantly for getting foreign key constraints and indexes and the like. – Peter DeGlopper Aug 07 '13 at 16:52
3

syncdb will not add new column and if the table already exist it will not create no new table. the thing i used to do is simply after adding the field name in your model. get within the shell and type:

$ python manage.py dbshell 

you will get directly within your database shell (mysql or psql) it up to what database
you are using.

mysql> | psql> ALTER TABLE <table_name> ADD column varchar(100);

and it will add the new column to your table, doesn't matter if the table it already populated or not.
drabo2005
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0

In development, I use the reset function a lot. It's useful for me as I don't mind blowing away dev data. It basically makes new database tables for just that app - so it will remove your data. Not useful if you wish to keep the data populated, south is better as mentioned above.

python manage.py reset <app-name>
professorDante
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    `reset` is deprecated as of 1.5. It's handy when your situation is simple enough, but it can have major problems with constraints. https://code.djangoproject.com/ticket/14268 links to some specifics, and the note "Resetting individual tables is a hard problem; Django can't be a substitute for a good DBA in this case." – Peter DeGlopper Aug 07 '13 at 17:22