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自定义EF Core addor用复合键更新

any composite-primary-key entity-framework-core entity-framework

0

materight · 技术社区 · 6 年前

Microsoft.EntityFrameworkCore 实现 AddOrUpdateMethod . 它工作正常,但是对于具有复合主键的实体 AnyAsync

方法如下:

public static async Task AddOrUpdateAsync<TEntity>(this DbSet<TEntity> table, Expression<Func<TEntity, object>> key, Expression<Func<TEntity, bool>> deleteExpression, params TEntity[] entities) where TEntity : class
{
    var getKeyFunction = key.Compile();
    var getShouldDeleteFunction = deleteExpression.Compile();
    var context = GetDbContext(table);
    foreach (var entity in entities)
    {
        var primaryKey = getKeyFunction(entity);
        var body = Expression.Equal(Expression.Convert(key.Body, primaryKey.GetType()), Expression.Constant(primaryKey));
        Expression<Func<TEntity, bool>> query = Expression.Lambda<Func<TEntity, bool>>(body, key.Parameters);
        var exist = await table.AnyAsync(query);
        context.Entry(entity).State = exist
            ? getShouldDeleteFunction(entity) ? EntityState.Deleted : EntityState.Modified
            : getShouldDeleteFunction(entity) ? EntityState.Detached : EntityState.Added;
    }
}

private static DbContext GetDbContext<T>(this DbSet<T> table) where T : class
{
    var infrastructure = table as IInfrastructure<IServiceProvider>;
    var serviceProvider = infrastructure.Instance;
    var currentDbContext = serviceProvider.GetService(typeof(ICurrentDbContext)) as ICurrentDbContext;
    return currentDbContext.Context;
}

我是这样用的:

await db.Reports.AddOrUpdateAsync(r => new { r.Number, r.Year }, r => r.Active == false, response.Reports.ToArray());

我认为这是因为我使用了匿名类型作为密钥,但我不知道如何解决这个问题。

0 回复 | 直到 6 年前

1

3

Ivan Stoev 6 年前

问题似乎是使用了匿名类型常量表达式,这导致了 client evaluation ,和C#运算符 == 通过引用比较匿名类型,因此总是返回 false .

key 带的表达式 entity 将参数替换为 Expression.Constant(entity) Expression.Invoke 在这种情况下不起作用)

所以把线移走 var getKeyFunction = key.Compile();

foreach (var entity in entities)
{
    var parameter = key.Parameters[0];
    var body = Expression.Equal(
        key.Body,
        key.Body.ReplaceParameter(parameter, Expression.Constant(entity))
    );
    var query = Expression.Lambda<Func<TEntity, bool>>(body, parameter);
    var exist = await table.AnyAsync(query);
    // ...
}

哪里 ReplaceParameter 是常用的表达式助手方法:

public static partial class ExpressionUtils
{
    public static Expression ReplaceParameter(this Expression expression, ParameterExpression source, Expression target)
        => new ParameterReplacer { Source = source, Target = target }.Visit(expression);

    class ParameterReplacer : ExpressionVisitor
    {
        public ParameterExpression Source;
        public Expression Target;
        protected override Expression VisitParameter(ParameterExpression node)
            => node == Source ? Target : node;
    }
}