Sequelize Command Examples (with examples)

Sequelize is a promise-based Node.js ORM (Object-Relational Mapping) that provides an easy way to interact with various relational databases such as Postgres, MySQL, MariaDB, SQLite, and Microsoft SQL Server. In this article, we will explore eight different use cases of the sequelize command by providing code examples and explanations for each.

Create a model with 3 fields and a migration file:

To create a model with three fields and generate a migration file, you can use the sequelize model:generate command. This command will create a new model file with the specified fields and generate a migration file that can be used to modify the database schema.

sequelize model:generate --name table_name --attributes field1:integer,field2:string,field3:boolean

• Motivation: Creating a model with fields and generating a migration file is essential when you need to modify the database schema and keep track of changes. This command simplifies the process of creating both the model and migration files.
• Arguments:
  • --name: The name of the table/model.
  • --attributes: The attributes/fields of the table/model, specified as a comma-separated list of field definitions with their data types.
• Example Output: This command will generate a new model file named table_name.model.js and a migration file named timestamp-create-table_name.js in the appropriate directories.

Run the migration file:

To run the migration file and apply the changes to the database, you can use the sequelize db:migrate command. This command will execute all pending migrations and update the database schema accordingly.

sequelize db:migrate

• Motivation: Migrations allow you to manage changes to your database schema, making it easy to version-control and collaborate on database changes. Running the migration file ensures that any pending changes are applied to the database.
• Arguments: None.
• Example Output: This command will execute all pending migration files and update the database schema. It will display log messages indicating the status of each migration.

Revert all migrations:

To revert all migrations and undo the changes made to the database, you can use the sequelize db:migrate:undo:all command. This command will revert all migrations in the order they were applied.

sequelize db:migrate:undo:all

• Motivation: Reverting all migrations can be useful when you want to roll back the database schema to a previous state or start fresh. This command allows you to easily undo all changes made by applying migrations.
• Arguments: None.
• Example Output: This command will undo all migrations applied to the database, reverting the changes made to the database schema. It will display log messages indicating the status of each migration being reverted.

Create a seed file with the specified name to populate the database:

To create a seed file with the specified name and populate the database with sample data, you can use the sequelize seed:generate command. This command will generate a new seed file in the appropriate directory, which can be used to populate the database.

sequelize seed:generate --name seed_filename

• Motivation: Seed files allow you to populate the database with initial data or sample data that is required for testing or development purposes. Creating a seed file with the specified name simplifies the process of generating seed files.
• Arguments:
  • --name: The name of the seed file.
• Example Output: This command will generate a new seed file named timestamp-seed_filename.js in the appropriate directory.

Populate database using all seed files:

To populate the database using all seed files, you can use the sequelize db:seed:all command. This command will execute all seed files in the order they were created, populating the database with the data specified in the seed files.

sequelize db:seed:all

• Motivation: Populating the database with seed data can be useful when you want to ensure that the database contains some initial data for testing or development purposes. Running all seed files simplifies the process of populating the database.
• Arguments: None.
• Example Output: This command will execute all seed files in the appropriate directory. It will display log messages indicating the status of each seed file being executed and the resulting changes made to the database.

Conclusion

In this article, we explored eight different use cases of the sequelize command by providing code examples, motivations, explanations for each argument, and example outputs. These commands allow you to easily create models, generate migration files, run migrations, revert migrations, create seed files, and populate the database using seed data. Sequelize simplifies the process of interacting with relational databases, making it easy to manage database schema changes and populate the database with initial or sample data.