Question

我需要澄清我的问题。

我有一个方法可以做到这一点：

public static void SetEntityValue<TEntity>(ref TEntity entityToTransform, PropertyHelper entityProperty)
{
   // create type from entity
   Type t = entityToTransform.GetType();
   // get the property to set
   var prop = t.GetProperty(entityProperty.Name);
   // set the property value to the one parsed
   prop.SetValue(entityToTransform, entityProperty.Value, null);
}

PropertyHelper只包含两个属性，名称和值。

所以，我有一个采用Generic Type的方法，然后需要初始化一个新的并用值填充其属性，这个方法会这样做：

TEntity ReadIntoEntity<TEntity>(TEntity entity, XElement node)
{
    if (!node.HasElements)
        throw new IllFormedDocumentException("Entity found but contains no properties");

    var xmlProps = node.Elements();

    Type t1 = entity.GetType();

    // the line which initialises a new TEntity same as string myString = new string();
    TEntity newEntity = Activator.CreateInstance<TEntity>();

    var props = t1.GetProperties();
    var readableProps = props.Select(x => new PropertyHelper(GenericHelper.GetEntityProperty(x), GenericHelper.GetEntityValueAsObject<TEntity>(entity, x)));

    List<string> foundAProp = new List<string>();

    foreach (var el in xmlProps)
    {
        // iterate through all xml elements

        foreach (var prop in readableProps)
        {
            // check the prop exists in the xml set

            // We found a prop that exists!
            if (el.Name.ToString() == prop.Name.ToString())
            {
                foundAProp.Add(prop.Name.ToString());

                GenericHelper.SetEntityValue<TEntity>(ref newEntity, prop);
            }
        }
    }

}

这会像Non Generics一样吗：

MyEntity ReadIntoEntity(XElement node)
{
    if (!node.HasElements)
        throw new IllFormedDocumentException("Entity found but contains no properties");

    var xmlProps = node.Elements();

    MyEntity newEntity = new MyEntity();

    var props = typeof(MyEntity).GetProperties();
    var readableProps = props.Select(x => new PropertyHelper(GenericHelper.GetEntityProperty(x), GenericHelper.GetEntityValueAsObject<TEntity>(entity, x)));

    List<string> foundAProp = new List<string>();

    foreach (var el in xmlProps)
    {
        // iterate through all xml elements

        foreach (var prop in readableProps)
        {
            // check the prop exists in the xml set

            // We found a prop that exists!
            if (el.Name.ToString() == prop.Name.ToString())
            {
                foundAProp.Add(prop.Name.ToString());

                GenericHelper.SetEntityValue<MyEntity>(ref newEntity, prop);
            }
        }
    }

}

如此有效：

TEntity newEntity = Activator.CreateInstance<TEntity>();

相当于：

MyEntity newEntity = new MyEntity();

由于

Answer 1

那种方法能做到吗？试试吧，看看。

然而：

TEntity newEntity = Activator.CreateInstance<TEntity>();

应替换为

TEntity newEntity = new TEntity();

为参数添加new()通用约束后

。这将添加编译时检查以确保实体具有有效的无参数构造函数。即：

TEntity ReadIntoEntity<TEntity>(TEntity entity, XElement node)
    where TEntity : class, new()
{
    // ...

假设您的所有实体都是ref类型，那么您的第一种方法就不需要class。

铸造通用类型然后使用参考

1 个答案: