Last update: January 30, 2024

Creating Custom Module with DB Agnostic Approach¶

Use this technique if you want to develop a module that can work with different database systems without having to rewrite your code for each one.

Virto Commerce Module Templates for Dotnet is a tool that helps you generate the basic structure and files for a new module based on some parameters.

To create a new module with a database agnostic approach:

Run the following command to create a CustomerReviews folder containing all the required projects and files for your module:
```
dotnet new vc-module-dba-template --ModuleName CustomerReviews --Author "Jon Doe" --CompanyName VirtoCommerce
```
Open the solution in Visual Studio.

Module Template Features¶

The template key features are:

It generates four projects allowing your module to be database agnostic. Each project provides a specific implementation for working with a particular database system. The CustomerReviews.Data project serves as the common base for all database-related functionality. These projects are:
- CustomerReviews.Data
- CustomerReviews.Data.MySql
- CustomerReviews.Data.PostgreSql
- CustomerReviews.Data.SqlServer
The Data.[Provider] projects have a specific structure and configuration for each database system: MySql, PostgreSql, and SqlServer:
- Migrations folder contains the migration files for the database system.
- DbContextOptionsBuilderExtensions class contains the helper method for configuring the DbContextOptionsBuilder for specific database provider.
- [Provider]DbContextFactory class contains implementation of IDesignTimeDbContextFactory for for specific database provider.
- Readme.md file contains the instructions for configuring and migration creation the specific database provider.
The Data project contains the common data models and interfaces that are shared by all database systems.
The Module.Initialize method registers the DbContext service using the AddDbContext extension method from Virto Commerce Platform Core library.
The OnModelCreating extension method customizes the entity type configuration for different database systems using conditional compilation symbols. You can specify the properties, keys, indexes, relationships, etc. of your entities using a fluent API.

To use this feature, you need to implement the IEntityTypeConfiguration<TEntity> interface in your entity configuration classes. It defines a Configure method that takes an EntityTypeBuilder<TEntity> parameter and configures various aspects of the entity type.

Below is an example implementing this interface for CurrencyEntity:
```
public class CurrencyEntityConfiguration : IEntityTypeConfiguration<CurrencyEntity>
{
    public void Configure(EntityTypeBuilder<CurrencyEntity> builder)
    {
        builder.Property(x => x.ExchangeRate).HasColumnType("decimal").HasPrecision(18, 4);
    }
}
```