How to Create a Singleton DB Instance with Accessible Methods in Go?

How to Create a Singleton DB Instance

In this scenario, we aim to create a singleton DB instance with explicit methods to avoid boilerplate code. The provided code declares an interface, DBOperations, which outlines required methods. DBManager encapsulates the database connection and provides these methods. However, if you intend to call these methods on the singleton reference, modifications are necessary.

Solution:

Use the following approach:

1. Create an Exported Interface: Define an exported interface named Manager that declares the desired methods.
2. Implement Unexported Type: Implement the Manager interface in an unexported type, manager. This prevents external modification of the interface.
3. Initialize Global Variable: Create a global variable of the Manager interface type and initialize it using a package init() function.
4. Configure Package Initialization: The init() function runs automatically before any references to the package and initializes the database connection.

By implementing these steps, you can create a singleton DB instance with accessible methods without the need for explicit synchronization.

Catching and Returning Exceptions from gorm.Create()

To catch and return exceptions from gorm.Create(), modify the AddArticle method in manager as follows:

<code class="go">func (mgr *manager) AddArticle(article *article.Article) (err error) {
    if err := mgr.db.Create(article).Error; err != nil {
        return err
    }
    return nil
}</code>

This allows you to return the error object directly, enabling error handling in the calling code.

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