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Sequelize CLI (Command Line Interface), is an easy-to-use ORM (Object Relational Mapping) tool for Node.js that works with SQL databases. Sequelize also offers a wide range of features, including support for multiple dialects, transaction support, data validation, and association to sequelize cli create model.
With Sequelize, you can work more efficiently on your Node.js project, while still leveraging the power and flexibility of SQL databases. By following the steps outlined in this article, you'll be on your way to mastering Sequelize CLI.
To create a project that utilizes Postgres, and Sequelize you need to create a new directory. To generate a new directory please input the "mkdir" command and the desired folder name thereafter. In this example, we'll call the directory "sequelize-project".
To initiate designing a project that leverages Postgres with Sequelize along with the helpful 'Sequelize CLI' tooling; you must start with making a fresh directory to serve as its abode. You may execute this dutifully using 'mkdir', utilizing any fitting title accordingly which in our case will be "sequelize-project".
Here's a code snippet that demonstrates how to install Postgres, Sequelize, and the Sequelize CLI in a directory called "sequelize-project":
Follow these steps to create a new Sequelize project and open the project directory in your code editor.
By running npx sequelize-cli init, you'll create a basic project structure for your Sequelize application, including a config file, a models directory, and a migrations directory. This command will also create a .sequelizerc file, which allows you to configure certain aspects of Sequelize's behavior.
After initializing the Sequelize project using the CLI, the resulting project structure will include several subdirectories: config, migrations, models, and seeders. The config directory contains configuration files that allow your project to work with the Postgres database.
In order to set up your project for Postgres, you can access the config/config.json file and substitute the current code with the code provided below:
Take note of this piece of code - it entails a categorization into three discrete environments, denoted by their respective names: development, test, and production. The significance of each environment lies in its association with a specific Postgres database as well as setting out its individual host particulars along with dialects.
An important featured here is that all databases' naming conventions include the prefix "my_sequelize_project_". By customizing your project settings correspondingly you permit a troubleshoot-free protocol for interaction between it and your designated repository while using both Sequelize and its relevant CLI.
The command "npx sequelize-cli db:create" is used to create a new database in a Sequelize-based Node.js application.
To create a new model called "User" in a Sequelize-based Node.js application, we can use the command.
This command generates a model file and a migration file based on the provided information.
The generated model file for "User" is located in the "sequelize-project/models/user.js" directory and contains the code to organize and interact with the User data in the database.
Sequelize can be a powerful tool when utilized correctly. Here we have a code block that demonstrates how to create a User-model in a very clear way with four specified attributes: firstName, lastName, email and password; each attribute being given its own STRING data type.
To fully establish said Model through definition it leverages the use of sequelize.define(). Two inputs need to be provided when implementing this function - which ends up being the name chosen for our new model followed by an object containing those specific details pertaining to the models attributes & any additional details.
The associate() method is left empty for now, but this is where we can define any relationships between the User model and other models in the application.
Overall, this model file will help organize and interact with the User data in the database via the directory path as sequelize-project/migrations/20190914184520-create-user.js:
The Sequelize CLI generates migration files with timestamps based on the current time and date. As a result, the timestamp in the file name, such as "20190914184520", will be different each time a new migration is created.
Sequelize cli migration refers to the process of using the Sequelize Command-Line Interface (CLI) to manage and apply database migrations in a Sequelize project. To execute sequelize cli migration, create the Users table and necessary columns in our Postgres database. Now, run the following command:
Next, we'll create a seed file using the following command:
In the generated seed file, you can replace the temporary data with actual data you want to use to describe the code.
In the above code snippet, up is the function that inserts the data into the Users table, while down is the function that removes the data. We use queryInterface.bulkInsert to insert the data and queryInterface.bulkDelete to remove it. The createdAt and updatedAt fields are set to the current date and time using the new Date() function.
After creating the seed file, we can execute it using the following command:
This will insert the data we specified in the seed file into the Users table in our Postgres database.
To check if the data has been successfully inserted, we can drop into psql and query the database by running the following commands:
The first command opens the psql shell and connects to our development database. The second command selects all rows from the Users table.
If the data has been inserted correctly, we should see a single row showing the information we included in our seed file, such as:
Sequelize CLI with TypeScript brings the power of a robust Object-Relational Mapping (ORM) library together with the benefits of TypeScript's static typing. This dynamic duo empowers developers to build scalable and maintainable applications with ease. The Sequelize CLI seamlessly integrates with TypeScript, enabling you to define models, establish associations, and perform database operations using TypeScript's strong typing system.
With Sequelize CLI and TypeScript, you can enjoy enhanced code readability, autocompletion, and type safety, minimizing errors and boosting productivity. This powerful combination simplifies the development process, making it easier to build sophisticated database-driven applications while ensuring code quality and maintainability.
It’s clear that Sequelize CLI is a powerful tool for working with databases in Node.js applications. With Sequelize CLI, you can easily create models, migrations, and seed files for your databases, and execute them with simple commands. This saves a lot of time and effort compared to writing database-related code from scratch.
By following the steps outlined in this topic, get started with Sequelize CLI and use it to set up a basic database with a Users table, insert data into the table, and query the data to verify that it has been successfully inserted. Till then, build more complex database structures and perform advanced operations with ease, using Sequelize CLI.