Adding Configurations When Creating a Database

Let's see how we can add additional validations using Entity Framework

Creating an Application

How to create .NET web-API

Connecting to a Database

Working with SQLite in .NET (Code first)

Adding Validation

Add the 'IEntityTypeConfiguration' interface in the context class and implement the interface

After implementation, a method to configure will be added at the bottom (I moved it to the top manually)

▶ Adding Validations

We can use the property method to add validations to the entities and properties

builder.Property()

builder.Property(p => p.Description).HasMaxLength(200);

▶ Adding Types

We can use the property method to add types to the properties

builder.Property(d => d.Fee).HasColumnType("decimal(18,2)");

For instance, we can add a 'decimal' type to Sqlite which does not have the type.

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※ Items that have a spanner icon are attributes

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Override the 'OnModelCreating' method to use the configuration at the bottom

using System.Reflection;
using Microsoft.EntityFrameworkCore.Metadata.Builders;

protected override void OnModelCreating(ModelBuilder modelBuilder)
{
  base.OnModelCreating(modelBuilder);
  modelBuilder.ApplyConfigurationsFromAssembly(Assembly.GetExecutingAssembly());
}

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※ We can have a separate folder to organize our files

 

Create a folder

Add a C# class

Add the interface and validation as shown above (Or move the configuration file if already have one. In this scenario, additional work might be needed depending on where the file was located)

Add the overriding 'OnModleCreating' method in the context file

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In this writing, we have seen how we can add validations when creating a database in a .NET application