Sometimes you realize that you need to add some new fields to an existing sequelize migrations. This is especially important for production apps where refreshing the migration is not an option. Below is a quick guide on how to implement it.
Let's assume you want to add some new fields to Users table; below are the steps.
Step 1 - Create a new migration
npx sequelize-cli migration:create --name modify_users_add_new_fields
Step 2 - Edit the migrations to suit the need
module.exports = {
up(queryInterface, Sequelize) {
return Promise.all([
queryInterface.addColumn(
'Users', // table name
'twitter', // new field name
{
type: Sequelize.STRING,
allowNull: true,
},
),
queryInterface.addColumn(
'Users',
'linkedin',
{
type: Sequelize.STRING,
allowNull: true,
},
),
queryInterface.addColumn(
'Users',
'bio',
{
type: Sequelize.TEXT,
allowNull: true,
},
),
]);
},
down(queryInterface, Sequelize) {
// logic for reverting the changes
return Promise.all([
queryInterface.removeColumn('Users', 'linkedin'),
queryInterface.removeColumn('Users', 'twitter'),
queryInterface.removeColumn('Users', 'bio'),
]);
},
};
Step 3 - Update the model with the new fields
Step 4 - Run migration
npx sequelize-cli db:migrate
That is it, you have successfully added new fields to an existing migration.
Top comments (16)
Hi, great tutorial. Does this keep the data in the database? or does it remove all data?
"npx sequelize-cli db:migrate" keeps the data in the database. To wipe the database you'd need to do "npx sequelize-cli db:migrate:undo:all" before "npx sequelize-cli db:migrate"
If a migration is rolled back, I think that will remove data.
Keeps data
@nedsoft please I want to ask how can one generate migration from existing model, say you have model in user.js file and you already defined your user model
how do I now generate migration base on this existing model?
Sequelize supports a feature called "model migrations," where you can generate and apply migrations directly from your Sequelize model definitions. This approach simplifies the process of making schema changes. You can use the npx sequelize migration:generate command with the --name option to create a migration based on changes in your models. For example:
npx sequelize migration:generate --name update-models
This command will generate a migration file with changes based on the differences between your models and the current database schema. You can then run the migration as usual.
Note that this approach requires you to have well-defined Sequelize models that accurately represent your database schema.
How to maintain sequence of the coloumn to be added while creating the coloumn. if I need to add the coloumn after a particular coloumn which already exists. By the above implementation the coloumn will always be added at the end of the list.
Hi all,
When I run npx sequelize-cli db:migrate I got this error:
Cannot find "{myPath}/config/config.json". Have you run "sequelize init"?
I don't have a config.json file, should I create it or maybe it should be created by npx sequelize-cli migration:create --name modify_users_add_new_fields ?
If I have to create, how it should be?
Thanks all guys
This tutorial describes how to extend a existing migration. If you haven't used the CLI for your project, you have to initialize it by npx sequelize init
Thanks very much !
there is no much tutorials for these things out there!
what fi i want to add the new field after a particular field.
How can we add a column after specific column?
Like this:
return Promise.all([queryInterface.addColumn(
'users', // table name
'verifier', // new field name
{
type: Sequelize.STRING,
allowNull: true,
after: 'manager_bonus',
}
),
]);
Thanks, this was helpful
Luv ya Chinedu!
So, if we have to edit then we have to change in file that we created, or just use cli for edit in any file?