Deserialize Json from Twitter Trends Api-CodePudding

I tried to deserialize this JSON:

[
  {
    "trends": [
      {
        "name": "#GiftAGamer",
        "url": "http://twitter.com/search?q=#GiftAGamer",
        "promoted_content": null,
        "query": "#GiftAGamer",
        "tweet_volume": null
      },
      {
        "name": "#AskCuppyAnything",
        "url": "http://twitter.com/search?q=#AskCuppyAnything",
        "promoted_content": null,
        "query": "#AskCuppyAnything",
        "tweet_volume": 14504
      }
    ],
    "as_of": "2020-11-20T19:37:52Z",
    "created_at": "2020-11-19T14:15:43Z",
    "locations": [
      {
        "name": "Worldwide",
        "woeid": 1
      }
    ]
  }
]

So I've created 3 classes:

Public Class TwitterTrendApiResponse
    Public Property ttd As List(Of TwitterTrendDatas)
    Public Property datAsOf As String
    Public Property datCreatedAt As String
    Public Property ttl As List(Of TwitterTrendLocation)
End Class
Public Class TwitterTrendLocation
    Public Property strName As String
    Public Property intWoeid As String
End Class
Public Class TwitterTrendDatas
    Public Property strName As String
    Public Property strUrl As String
    Public Property strPromotedContent As String
    Public Property strQuery As String
    Public Property intVolume As String
End Class

and i've tried deserialize with:

Dim result As TwitterTrendApiResponse = JsonConvert.DeserializeObject(strMyJsonToDeserialize)

But I've got an exeception "Unable to cast object of type 'Newtonsoft.Json.Linq.JArray' to type TwitterTrendApiResponse. Where did i go wrong?

CodePudding user response：

You have to change this:

Dim result As TwitterTrendApiResponse = JsonConvert.DeserializeObject(strMyJsonToDeserialize)

In:

Private myDeserializedClass As Object = JsonConvert.DeserializeObject(Of List(Of TwitterTrendApiResponse))(strMyJsonToDeserialize)

As you can see at the JSON data the root node is an array. THen take care of type of returned object if it is an array or a single class, to declare it properly. AS List(Of TwitterTrendApiResponse) or AS TwitterTrendApiResponse

CodePudding user response：

as a matter of fact your json is a list of objects, not just an object. So try this

Dim result As  List( Of ResponseListElements) = JsonConvert.DeserializeObject(Of List( Of ResponseListElements))(strMyJsonToDeserialize);

and fix the classes

 Public Class ResponseListElements
        Public Property trends As Trend()
        Public Property as_of As DateTime
        Public Property created_at As DateTime
        Public Property locations As Location()
    End Class

 Public Class Trend
        Public Property name As String
        Public Property url As String
        Public Property promoted_content As Object
        Public Property query As String
        Public Property tweet_volume As Integer?
    End Class

    Public Class Location
        Public Property name As String
        Public Property woeid As Integer
    End Class