Dapper.DDD.Repository.Sql 1.7.0

Dapper.DDD.Repository.Sql

This package provides support for using Dapper.DDD.Repository with MS SQL Server.

Usage

Install the package Microsoft.Data.SqlClient in your project. Then simply provide an instance of SqlQueryGenerator as your QueryGenerator, set your Schema and create a SqlConnectionFactory in your project, and you're done:

	...
	options.ConnectionFactory = new SqlConnectionFactory("CONNECTIONSTRING");
	options.QueryGeneratorFactory = new SqlQueryGeneratorFactory();
	options.Schema = "dbo"; // Default schema, adjust if necessary
	...

Also here's a simple SqlConnectionFactory you can use:

using System.Data;
using Dapper.DDD.Repository.Interfaces;
using Microsoft.Data.SqlClient;

namespace YOUR_NAMESPACE_HERE;

internal class SqlConnectionFactory : IConnectionFactory
{
	private readonly string _connectionString;

	public SqlConnectionFactory(string connectionString)
	{
		if (string.IsNullOrWhiteSpace(connectionString))
			throw new ArgumentException("connectionString cannot be null or whitespace.", nameof(connectionString));

		_connectionString = connectionString;
	}

	public IDbConnection CreateConnection()
	{
		return new SqlConnection(_connectionString);
	}
}

Using Geometry and Geography

Dapper doesn't inherently play that well with these column types, however this package has a solution for it. In this example I'll use NetTopologySuite for my C# Geometry classes, but the principle is the same if you're using Microsoft's classes (or even some other third party).

The solution is actually rather simple: Serialize Geometry/Geography columns to binary, as this is supported by Dapper. To do so requires two configurations:

• The SqlQueryGeneratorFactory needs to know which types to serialize in order to generate the proper SQL (which looks like this: ([dbo].[Table].[Column]).Serialize() AS [Column])
• TypeConverters needs to be added for actually converting to/from binary

Here's an example of such a configuration for the Point type from NetTopologySuite - use the same approach for any other types:

	using NetTopologySuite.Geometries;
	using NetTopologySuite.IO;
	...
	services.ConfigureDapperRepositoryDefaults(options =>
	{
		...
		options.QueryGeneratorFactory = new SqlQueryGeneratorFactory().SerializeColumnType(type => type.Namespace == "NetTopologySuite.Geometries"); // This ensure any Geometry type from NetTopologySuite gets serialized in the queries
		options.AddTypeConverter<Point, byte[]>(geo => new SqlServerBytesWriter() { IsGeography = false }.Write(geo), bytes => (Point)new SqlServerBytesReader() { IsGeography = false }.Read(bytes)); // Set IsGeography to true if you're using geography and not geometry
		...
	}

And that's basically it, now you can define properties of the type Point in any of your aggregates and the built-in ITableRepository will work correctly.

There are however still 2 caveats to look out for:

• You need to remember to .Serialize() your column manually for your own queries, otherwise you'll get an exception similar to this: System.Data.DataException : Error parsing column
• There is currently no way to support both geography and geometry of the same C# type simultaneously. This is because only a single TypeConverter can exist for a single type. A workaround might be to declare two classes yourself and use those instead like this:

	public class GeometryPoint : Point
	{
		...
	}

	public class GeographyPoint : Point
	{
		...
	}
	...
	options.AddTypeConverter<GeometryPoint, byte[]>(geo => new SqlServerBytesWriter() { IsGeography = false }.Write(geo), bytes => (GeometryPoint)new SqlServerBytesReader() { IsGeography = false }.Read(bytes));
	options.AddTypeConverter<GeographyPoint, byte[]>(geo => new SqlServerBytesWriter() { IsGeography = true }.Write(geo), bytes => (GeographyPoint)new SqlServerBytesReader() { IsGeography = true }.Read(bytes));

Note: I haven't tested this approach myself, so it might not be that simple! It depends on whether the SqlServerBytesReader can deal with custom types or not.

Known issues with Geometry and Geography

These 2 exceptions will appear if you've missed one of the steps above:

• System.Data.DataException : Error parsing column: You've not added .SerializeColumnType to your SqlQueryGeneratorFactory, it's not correctly detecting the type or you've forgotten to call .Serialize() in your own custom Query.
• System.ArgumentException : An item with the same key has already been added. Key: Item: You've not added a TypeConverter for one or more of your C# geometry types.