[英]Returns json result and convert null to empty string
I have an action that returns json result, but some of the attributes are null and I want to convert them to empty strings instead. 我有一个返回json结果的动作,但有些属性为null,我想将它们转换为空字符串。 I heard I can use
DefaultValue("")
, but it's still returning null
instead of empty string. 我听说我可以使用
DefaultValue("")
,但它仍然返回null
而不是空字符串。
The action is: 行动是:
[HttpGet]
public ActionResult GetResults(string date)
{
var data= GetData(); // returns List<Foo>
var json = Json(data, JsonRequestBehavior.AllowGet);
return json;
}
The Foo
class is: Foo
类是:
public class Foo
{
public string Bar1;
[DefaultValue("")]
public int? Bar2;
}
you can't set a nullable int
to default val of ""
你不能将一个
nullable int
设置为默认值""
Try 尝试
[DefaultValue(0)]
public int? Bar2;
Like @Dave A noticed you can not assign string value to the int value. 像@Dave A注意到你不能将字符串值赋给int值。
However one thing that I wanted to warn it, have you set properly the property DefaultValueHandling
? 但是有一件事我想警告它,你有没有正确设置
DefaultValueHandling
属性? Check it here: Removing Default Values in JSON with the MVC4 Web API 在此处查看: 使用MVC4 Web API删除JSON中的默认值
Besides that I would recommend to you that you do a string property that represent this Bar2 int property and you "Ignore" it for serialization, like: 除此之外,我建议您使用表示此Bar2 int属性的字符串属性,并“忽略”它以进行序列化,例如:
[JsonIgnore]
[DefaultValue(0)]
public int? Bar2Int;
public string Bar2
{
return { Bar2Int.HasValue ? this.Bar2Int.Value.ToString() : String.Empty; }
}
Even better with this approach you do not need any default values attributes. 使用此方法更好,您不需要任何默认值属性。
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