如何在.NET中进行查询之前检查未定义的值？

Question

我得到的错误如下。我发现当我查询一个“未定义”的字段时会发生这种情况。

那么如何检查Parse中未定义的字段？

"Message": "An error has occurred.",
    "ExceptionMessage": "The given key was not present in the dictionary.",
    "ExceptionType": "System.Collections.Generic.KeyNotFoundException",
    "StackTrace": "   at System.Collections.Generic.Dictionary`2.get_Item(TKey key)\r\n   at Parse.ParseObject.get_Item(String key)\r\n   at Parse.ParseObject.Get[T](String key)\r\n  

Answer 1

假设您指的是Parse.com平台的ParseObject类，您可以在调用Get之前使用ParseObject.ContainsKey方法检查密钥是否存在，例如：< / p>

if (someParseObject.Contains(someKey))
    myVar=someParseObject.Get(someKey);