尝试将两种不同的类型映射到一个值 [英] Trying to map two different types to one value

问题描述

我有一个 DataMember ，需要用api json字符串填充...

I have a DataMember that I need to be filled in by an api json string...

[DataContract]
public class Values
{
    [DataMember]
    public object value { get; set; }
}

API json字符串：

[
    {
        "type": "text",
        "values": [
            {
                "value": "Text that is in textfield"
            }
        ]
    },
    {
        "type": "category",
        "values": [
            {
                "value": {
                    "text": "Category title",
                    "color": "#000000"
                }
            }
        ]
    }
]

我将此字符串映射到一个强类型对象 Field ，如下所示：

I map this string to a strong typed object Field like so:

    private List<Field> PrepFieldObject(string response)
    {
        using (MemoryStream stream = new MemoryStream(Encoding.UTF8.GetBytes(response)))
        {
            DataContractJsonSerializer serializer = new DataContractJsonSerializer(typeof(List<Field>));
            return (List<Field>)serializer.ReadObject(stream);
        }
    }

但是当它映射到 Values.value ，它发出嘶嘶声……我试图这样解决：

but when it gets to mapping Values.value, it throws a hissy fit... I tried solving it like this:

[DataContract]
public class Values
{
    [DataMember]
    public object value
    {
        get {
            return xamlValue;
        }
        set
        {                     
            xamlValue = new Value();

            if( value is string )
            {
                 xamlValue.text = (string)value; // This works fine
            }
            else
            {

                Value theValue = value as Value;
                try
                {
                    xamlValue.text = theValue.text; // Can't get hold of .text even though it does exist in the json.
                    xamlValue.color = theValue.color;
                }
                catch (Exception e)
                {
                }
            }
        }
    }
    public Value xamlValue { get; set; }
}

[DataContract]
public class Value
{
    [DataMember]
    public string text { get; set; }
    [DataMember]
    public string color { get; set; }
}

但是它不允许我访问对象的属性（我想是因为它们从未被DataContract映射）

我尝试添加

[KnownType(typeof(Value))]
[KnownType(typeof(string))]

但这也无济于事：'（

推荐答案

我认为您可以使用反射来访问对象的属性值
尝试将设置者的else部分更改为

I think you can use reflection to to access your object's property value. Try changing your setter's else part as

else
    {

        Value theValue = value as Value;
        try
        {   
            // pass the object and the property name you're trying to get hold of
            xamlValue.text = PropertyHasValue(theValue, "text"); // Can't get hold of .text even though it does exist in the json. 
            xamlValue.color = PropertyHasValue(theValue, "color");
        }
        catch (Exception e)
        {
        }
    }

以及反射方法

// using reflection to get the object's property value
public static String PropertyHasValue(object obj, string propertyName)
{
    try
    {
        if (obj != null)
        {
            PropertyInfo prop = obj.GetType().GetProperty(propertyName, BindingFlags.Instance | BindingFlags.Public);
            if (prop != null)
            {
                string sVal = String.Empty;
                object val = prop.GetValue(obj, null);

                if (prop.PropertyType != typeof(System.DateTime?))
                    sVal = Convert.ToString(val);
                else // format the date to contain only the date portion of it
                    sVal = Convert.ToDateTime(val).Date.ToString("d"); ;

                if (sVal != null)
                {
                    return sVal;
                 }
             }
        }

        return null;
    }
    catch
    {
        return null;
    }
}

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