RIA服务+实体框架4+POCO's:'The Timestamp field is required'错误?

解决方案:

我已将T4生成的用户类更改为:

public partial class User : IEntity
{
    public virtual long Id
    {
        get;
        set;
    }
    ...

    [TimestampAttribute]
    [SuppressMessage("Microsoft.Performance", "CA1819:PropertiesShouldNotReturnArrays", Justification = "Autogenerated by T4.")]
    public virtual byte[] Timestamp
    {
        get;
        set;
    }

    ...
}

我还添加了一个通用的元数据类,它被排除 时间戳 属性:

/// <summary>
/// A MetaData which defines some default metadata for an Entity
/// </summary>
public class EntityMetaData
{
    /// <summary>
    /// Initializes a new instance of the <see cref="EntityMetaData"/> class.
    /// </summary>
    protected EntityMetaData()
    {
    }

    /// <summary>
    /// Gets or sets the timestamp.
    /// Note : this field is excluded on the client.
    /// </summary>
    /// <value>The timestamp.</value>
    [Exclude]
    public byte[] Timestamp { get; set; }
}

这就解决了问题。

一个选择是设置 Nullable true 在EDMX模型中,但保持 NOT NULL 数据库中的约束。

作为生成的类型 Timestamp ( RowVersion )是引用类型( byte[] null 值,则不应破坏任何现有代码。