EntityFrameworkCore.SqlExpressions

EntityFrameworkCore.SqlExpressions permet d'enregistrer des SqlExpressions simplement dans le mecanisme de rendu d' EntityFramework

EntityFrameworkCore.SqlExpressions.InMemory

Il est possible de faire simplement vos tests d'integration via cette librairie InMemory

Usage

Configuration

        
        services.AddDbContextPool<NorthwindContext>(builder =>
            builder.UseSqlServer("Data Source=localhost;Initial Catalog=Northwind;",
                optionsBuilder =>
                {
                    optionsBuilder.UseAddedExpressions(add =>
                    {
                        add(new SqlExpressionConfiguration(CustomSqlDbFunctionsExtensions.DeclaringType,
                            CustomSqlDbFunctionsExtensions.MyCustomMethodInfo,
                            arguments => new MyCustomSqlExpression(arguments)));
                    });
                }));

DbFunctionExtensions

public static class CustomSqlDbFunctionsExtensions
{
    public static Type DeclaringType { get; } = typeof(CustomSqlDbFunctionsExtensions);

    public static MethodInfo MyCustomMethodInfo { get; } =
        DeclaringType.GetMethod(nameof(MyCustom), new[] { typeof(DbFunctions), typeof(int) })!;

    public static string MyCustom(this DbFunctions _, int value) =>
        throw new InvalidOperationException(CoreStrings.FunctionOnClient(nameof(MyCustom)));
}

Custom SqlExpression

public sealed class MyCustomSqlExpression : SqlExpression
{
    private readonly SqlExpression[] sqlExpressions;

    private static readonly StringTypeMapping relationalTypeMapping;
    
    private static readonly SqlConstantExpression constantExpression;
    
    private static readonly Type stringType;

    public MyCustomSqlExpression(SqlExpression[] sqlExpressions) : base(stringType, relationalTypeMapping)
    {
        this.sqlExpressions = sqlExpressions.Prepend(constantExpression).ToArray();
    }

    static MyCustomSqlExpression()
    {
        relationalTypeMapping = new("nvarchar(max)", DbType.String);
        stringType = typeof(string);
        constantExpression = new SqlConstantExpression(Constant("-> ", stringType), relationalTypeMapping);
    }

    protected override Expression VisitChildren(ExpressionVisitor visitor)
    {
        return new SqlFunctionExpression("CONCAT", this.sqlExpressions, false,
            this.sqlExpressions.Select(_ => false), stringType,
            this.TypeMapping);
    }

    protected override void Print(ExpressionPrinter expressionPrinter)
    {
        expressionPrinter.Visit(this);
    }
}

Query

var result = dbContext.Regions.Select(r => EF.Functions.MyCustom(r.RegionId)).ToList();

License (MIT)