Venflow Setup

Configure the Database

Warning

Be aware, that LINQPad may throw unexpected errors and you therefore should use a real .Net Project instead.

In Venflow you are reflecting your PostgreSQL database with the Database class, which will host all of your tables. In the following example we will configure a database containing two tables, Blogs and Posts. One Blog contains many posts and a post contains a single Blog.

public class BlogDatabase : Database
{
    public Table<Blog> Blogs { get; set; }
    public Table<Post> Posts { get; set; }

    public BlogDatabase() : base("Your connection string.")
    {
    }
}

Note

Usually you would use your Database with an IOC Container and register it as a Transient/Scoped depending on the use.

Warning

This class represents a connection to your database and therefore doesn't support multi threaded use.

Entities

Entities represent a row inside a table of your database, for our current example this would look something like the following. Entities have to follow a specific schema:

• The Entity itself has to be public.
• All properties representing a column have to be public and need to have a public setter.

public class Blog
{
    public int Id { get; set; }
    public string Name { get; set; }
    
    public IList<Post> Posts { get; }
    
    public Blog()
    {
        Posts = new List<Post>();
    }
}

public class Post
{
    public int Id { get; set; }
    public string Title { get; set; }
    public string Content { get; set; }
    
    public int BlogId { get; set; }
    public Blog Blog { get; set; }
}

Note

You don't necessarily need to instantiate the Posts navigation property on the Blog Entity, since Venflow will instantiate them otherwise. However in most cases it is more convenient to instantiate them on your own, otherwise foreign collections might be null!

Warning

All properties which you want to be updateable by change-tracking have to be marked as virtual!

Configuring Entities

Now lets configure the actual relation between Blogs and Posts through the EntityConfiguration<T> class. In the Configure , method you can configure several things such as the name of the table this entity should map to and much more. These configuration classes do automatically get discovered, if they are in the same assembly as the Database class. If they are not in the same assembly, you can override the Configure method in the Database class which passes in a DatabaseOptionsBuilder, which will allow you to specify assemblies which should also be searched for entity configurations.

public class BlogConfiguration : EntityConfiguration<Blog>
{
    protected override void Configure(IEntityBuilder<Blog> entityBuilder)
    {
        entityBuilder.HasMany(b => b.Posts)
                     .WithOne(p => p.Blog)
                     .UsingForeignKey(p => p.BlogId);
    }
}

Note

Most of the configurations have to be configured with the IEntityConfiguration<T> interface, however there are a few exceptions to this rule.

• Primary Keys get automatically mapped if they are named Id or decorated with the KeyAttribute.
• A property can also be ignored with the NotMappedAttribute.