Data Retrieve With Eloquent From One to Many Relationship Table

If you are new to Laravel development, you might wonder how to retrieve data from a one-to-many relationship table using Eloquent. In this guide, we will explore the necessary steps and provide examples to help you get started.

First, let’s define what a relationship is. In Laravel, a relationship connects two database tables that allow you to retrieve related data. Different types of relationships exist, such as one-to-one, one-to-many, and many-to-many. In this article, we will focus on one-to-many relationships.

Creating One-to-Many Relationship

To define a one-to-many relationship, you need two database tables: a “users” table and a “roles” table. The “users” table has a “user_id” column that serves as the foreign key in the “roles” table. This means that each user can have multiple roles.

All models in Laravel extend the eloquent model class.(Illuminate\Database\Eloquent\Model:class) To create the relationship, you must define it in the User model. Here’s an example:

This code defines a “roles” method that returns a hasMany eloquent relationship. This means that each user can have multiple roles, and each role belongs to only one user.

Now that we have defined the relationship, we can retrieve the related data using Eloquent. To retrieve a user’s roles, you can use the following code:

In this code, we first retrieve the user with an ID of 1 using the find method. Then we access the user’s roles using the roles property. This returns a collection of Role models.

Defining the Inverse

You can also define the inverse of the relationship. This means that you can retrieve a user’s information from the Role model. To do this, you need to define the relationship in the Role model:

In this code, we define a “user” method that returns a belongsTo relationship. This means that each role belongs to only one user.

Now, you can retrieve a role’s user using the following code:

This code retrieves the role with an ID of 1 and then accesses the role’s user using the user property. This returns a User model.

Timestamps

By default, Eloquent will add created_at and updated_at timestamps to your database table. This means that the corresponding timestamp is updated each time a row is created or updated.

If you want to disable the timestamps, you can set the timestamps property in your model to false:

If you want to customize the timestamp column names, you can set the created_at and updated_at properties in your model:

This code sets the created_at column name to “creation_date” and the updated_at column name to “last_update“.

Return BelongsToMany

If you have a many-to-many relationship, you can use the belongsToMany method to retrieve the related data. Let’s say we have a “products” table and a “categories” table; each product can belong to multiple categories. We can define the relationship in the Product model like this:

In this code, we define a categories method that returns a belongsToMany relationship. This means that each product can belong to multiple categories, and each category can be associated with multiple products.

To retrieve a product’s categories, you can use the following code:

In this code, we first retrieve the product with an ID of 1 using the find method. Then we access the product’s categories using the categories property. This returns a collection of Category models.

Return HasMany Through

If you have a complex relationship, you can use the hasManyThrough method to retrieve the related data. Let’s say we have a “countries” table, a “states” table, and a “cities” table. Each country has many states, and each state has many cities. We can define the relationship in the Country model like this:

In this code, we define a cities method that returns a hasManyThrough relationship. This means that we can retrieve all the cities that belong to a country by going through the states table.

To retrieve a country’s cities, you can use the following code:

In this code, we first retrieve the country with an ID of 1 using the find method. Then we access the country’s cities using the cities property. This returns a collection of City models.

Retrieving data from a one-to-many relationship table using Eloquent is a powerful feature of Laravel that allows you to retrieve related data easily. This article has covered the necessary steps and provided examples to help you get started. We hope that this guide has been helpful to you as a newbie Laravel developer. If you have any questions or comments, feel free to leave them below.