Entity Framework Core

Structr.EntityFrameworkCore package provides methods to easily implement auto-auditing in Entity Framework Core DbContext, ModelBuilder extensions which applies the entity type default configuration and IQueryable<T> extensions to paginate through a list of entities.

Installation

EntityFrameworkCore package is available on NuGet.

dotnet add package Structr.EntityFrameworkCore

Usage

EntityFrameworkCore package have a reference to Structr.Domain package that provides some abstract classes for entities, value objects and interfaces which are intended to help to implement Domain Model.

Auto-auditing

Auto-auditing - it's entity change auditing for Entity Framework Core entities. The basic way to add auditing is to override the SaveChanges() method of the DbContext and plug in some logic for filling and tracking auditable properties (e.g. DateCreated or CreatedBy) automatically.

For example, create some entity that inherits Entity<TEntity,TKey> class and ICreatable interface.

public class Issue : Entity<Issue, int>, ICreatable
{
    public string Name { get; set; }
    public string Description { get; set; }
    public DateTime DateCreated { get; set; } // It's an auditable property from "ICreatable".
}

Create your own DbContext class implementation with configure some auditing dependencies (e.g. ITimestampProvider) and override SaveChanges() methods.

public class DataContext : DbContext
{
    public DbSet<Issue> Issues { get; set; };

    private readonly AuditTimestampProvider? _auditTimestampProvider;

    public DataContext(DbContextOptions<DataContext> options, ITimestampProvider? timestampProvider = null) 
        : base(options)
    {
        _auditTimestampProvider = timestampProvider != null ? timestampProvider.GetTimestamp : null;
    }

    public override int SaveChanges(bool acceptAllChangesOnSuccess)
    {
        this.Audit(_auditTimestampProvider); // Auto-audit entities.
        return base.SaveChanges(acceptAllChangesOnSuccess);
    }

    public override Task<int> SaveChangesAsync(bool acceptAllChangesOnSuccess, CancellationToken cancellationToken = default(CancellationToken))
    {
        this.Audit(_auditTimestampProvider); // Auto-audit entities.
        return base.SaveChangesAsync(acceptAllChangesOnSuccess, cancellationToken);
    }
}

Now if you add a new instance of Issue to DbSet<Issue> and call SaveChanges() or SaveChangesAsync() method, the DateCreated property will be filled in automatically.

Auto-configure entity types

Create your own DbContext class implementation and override OnModelCreating() method with calling ApplyEntityConfiguration(), ApplyValueObjectConfiguration() and/or ApplyAuditableConfiguration() methods.

public class DataContext : DbContext
{
    public DataContext(DbContextOptions<DataContext> options) 
    : base(options)
    {}

    protected override void OnModelCreating(ModelBuilder builder)
    {
        builder.ApplyEntityConfiguration();
        builder.ApplyValueObjectConfiguration();
        builder.ApplyAuditableConfiguration();
    }
}

ModelBuilder extension methods list:

Method name	Description
ApplyEntityConfiguration	Applies the default configuration for all classes inherited from the Entity<TEntity, TKey>. Automatically configures PK for entities with HasKey() method.
ApplyValueObjectConfiguration	Applies the default configuration for all classes inherited from the ValueObject<TValueObject>.
ApplyAuditableConfiguration	Applies the default configuration for all classes that implement the IAuditable.

You can configure options when applying entity types default configurations. For example, configure PK column name for all domain entities:

protected override void OnModelCreating(ModelBuilder builder)
{
    builder.ApplyEntityConfiguration(options =>
    {
        options.Configure = (entityType, builder) =>
        {
            builder.Property("Id")
                .HasColumnName($"{entityType.ClrType.Name}ID");
        };
    });
}

EntityConfigurationOptions properties:

Property name	Property type	Description
Configure	Action<IMutableEntityType, EntityTypeBuilder>	Delegate for configuring Entities. Default value is null.

Configure name strategy for all properties of value objects:

protected override void OnModelCreating(ModelBuilder builder)
{
    builder.ApplyValueObjectConfiguration(options =>
    {
        options.Configure = (entityType, navigationName, builder) =>
        {
            foreach (var property in entityType.GetProperties().Where(x => x.IsPrimaryKey() == false))
            {
                property.SetColumnName(navigationName + "_" + property.Name);
            }
        };
    });
}

ValueObjectConfigurationOptions properties:

Property name	Property type	Description
Configure	Action<IMutableEntityType, string, OwnedNavigationBuilder>	Delegate for configuring Value Objects. Default value is null.

Configure signed properties for auditable entities:

protected override void OnModelCreating(ModelBuilder builder)
{
    builder.ApplyAuditableConfiguration(options =>
    {
        options.SignedColumnIsRequired = true;
        options.SignedColumnMaxLength = 100;
    });
}

AuditableConfigurationOptions properties:

Property name	Property type	Description
SignedColumnMaxLength	int	Defines the maximum size of a signed column (CreatedBy, ModifiedBy, DeletedBy). Default value is 50.
SignedColumnIsRequired	bool	Defines if a signed column (CreatedBy, ModifiedBy, DeletedBy) is required. Default value is false.

Pagination

Use .ToPagedList() and .ToPagedListAsync() extension methods for IQueryable<T> to paginate result of entities query:

PagedList<Issue> issues = _dbContext.Issues
    .OrderByDescending(x => x.DateCreated)
    .ToPagedList(pageNumber: 1, pageSize: 10); // Returns only top 10 of latest issues.

If you call ToPagedList() method with pageSize parameter equals -1 that returns all entities from DbContext without limitation.