Nancy 模型绑定到子类

Question

我们遇到了与 Nancy 的默认模型绑定器有关的问题。鉴于以下...

public class Foo
{
    public Foo()
    {
    }

    public string Name { get; set; }

    public Bar Bar { get; set; }
}

public class Bar
{
    public string Name { get; set; }
}

带有...的元素

<input type="text" value="Name" />
<input type="text" value="Bar.Name" />

像这样使用默认模型绑定器..

var foo = this.Bind<Foo>();

这会正确绑定 Foo.Name 但无法绑定 Foo.Bar.Name

有没有办法使用默认绑定器启用这种绑定，还是我们需要自己滚动？如果有，有什么好的例子吗？

Answer 1

为什么不试试这个。我相当确定递归可以优化，并且在它不起作用的地方会出现一些问题，并且它可以放在比 IModelBinder 更聪明的地方，但它基本上可以满足您的需求。

/// <summary>
/// Sample model binder that manually binds customer models
/// </summary>
public class CustomModelBinder : IModelBinder
{
    /// <summary>
    /// Bind to the given model type
    /// </summary>
    /// <param name="context">Current context</param>
    /// <param name="modelType">Model type to bind to</param>
    /// <param name="blackList">Blacklisted property names</param>
    /// <returns>Bound model</returns>
    public object Bind(NancyContext context, Type modelType, params string[] blackList)
    {
        var parentObject = Activator.CreateInstance(modelType);

        foreach (var key in context.Request.Form)
        {
            var value = context.Request.Form[key];
            this.SetObjectValue(parentObject, modelType, key, value);
        }

        return parentObject;
    }

    /// <summary>
    /// Sets the object value.
    /// </summary>
    /// <param name="instance">The instance.</param>
    /// <param name="type">The type.</param>
    /// <param name="key">Name of the property.</param>
    /// <param name="propertyValue">The property value.</param>
    private void SetObjectValue(object instance, Type type, string key, string propertyValue)
    {
        if (key.Contains("."))
        {
            this.SetObjectValueDeep(instance, type, key, propertyValue);
        }

        PropertyInfo propertyInfo = type.GetProperty(key);
        if (propertyInfo == null)
        {
            return;
        }

        propertyInfo.SetValue(instance, Convert.ChangeType(propertyValue, propertyInfo.PropertyType), null);
    }

    /// <summary>
    /// Sets the object value derp.
    /// </summary>
    /// <param name="instance">The instance.</param>
    /// <param name="type">The type.</param>
    /// <param name="key">The key.</param>
    /// <param name="propertyValue">The property value.</param>
    private void SetObjectValueDeep(object instance, Type type, string key, string propertyValue)
    {
        var propList = key.Split('.').ToList();

        PropertyInfo propertyInfo = type.GetProperty(propList.First());
        if (propertyInfo == null)
        {
            return;
        }

        var childObject = propertyInfo.GetValue(instance, null);

        if (childObject == null)
        {
            childObject = Activator.CreateInstance(propertyInfo.PropertyType);
            propertyInfo.SetValue(instance, childObject, null);
        }

        propList.RemoveAt(0);

        var newKey = propList.Aggregate(string.Empty, (current, prop) => current + (prop + ".")).TrimEnd('.');

        if (newKey.Contains("."))
        {
            this.SetObjectValueDeep(childObject, childObject.GetType(), newKey, propertyValue);
        }
        else
        {
            this.SetObjectValue(childObject, childObject.GetType(), newKey, propertyValue);
        }
    }

    /// <summary>
    /// Determines whether this instance can bind the specified model type.
    /// </summary>
    /// <param name="modelType">Type of the model.</param>
    /// <returns>
    ///   <c>true</c> if this instance can bind the specified model type; otherwise, <c>false</c>.
    /// </returns>
    public bool CanBind(Type modelType)
    {
        return true;
    }
}