如何在 Visual Basic 2013 中反序列化 Json？

Question

我正在尝试将反序列化的 json 数据插入到 Visual Basic 2013 中的 sqlite 表中。但是，我在反序列化 json 数据时遇到了问题。 Json数据结构如下-

[
{
"QID":"1",
"Question_Text":"This is a demo question",
"Question_Media":null,
"Subject_Id":"1",
"Subject_Name":"Demo Subject",
"Topic_Id":"12",
"Topic_Name":"Demo Topic",
"Chapter_No":"11",
"Exam_Id":"58",
"Exam_Name":"Demo Exam",
"Explanation":"Demo Explanation",
"Explanation_Media":null,
"Reference":null,
"Option_01":"Lesser petrosal nerve",
"Option_01_Media":null,
"Option_01_isCorrect":"0",
"Option_01_Hint":null,
"Option_01_Hint_Media":null,
"Option_02":"Maxillary nerve",
"Option_02_Media":null,
"Option_02_isCorrect":"1",
"Option_02_Hint":null,
"Option_02_Hint_Media":null,
"Option_03":"Motor root of trigeminal nerve",
"Option_03_Media":null,
"Option_03_isCorrect":"0",
"Option_03_Hint":null,
"Option_03_Hint_Media":null,
"Option_04":"Sensory branch of mandibular nerve",
"Option_04_Media":null,
"Option_04_isCorrect":"0",
"Option_04_Hint":null,
"Option_04_Hint_Media":null,
"Option_05":null,
"Option_05_Media":null,
"Option_05_isCorrect":"0",
"Option_05_Hint":null,
"Option_05_Hint_Media":null,
"Option_06":null,
"Option_06_Media":null,
"Option_06_isCorrect":"0",
"Option_06_Hint":null,
"Option_06_Hint_Media":null,
"Added_By":"demo",
"Question_Type":"1",
"Created_At":"2015-03-07 22:58:01",
"Updated_At":"2015-03-14 22:56:08",
"DID":"0",
"Exams":null,
"Difficulty_Level":"1",
"isVerified":"0",
"isDuplicate":"0",
"isSeen":"0",
"isAnsweredCorrect":"0",
"isAnsweredWrong":"0",
"isMarked":"0",
"Remarks":null,
"isRepeat":"0",
"NotInExam":"0"
},
{
"QID":"2",
"Question_Text":"Demo question 2",
"Question_Media":null,
"Subject_Id":"1",
"Subject_Name":"Demo subject 2",
"Topic_Id":"12",
"Topic_Name":"Demo topic 2",
"Chapter_No":"11",
"Exam_Id":"58",
"Exam_Name":"Demo exam 2",
"Explanation":"Demo explanation 2",
"Explanation_Media":null,
"Reference":null,
"Option_01":"Hypothalamus",
"Option_01_Media":null,
"Option_01_isCorrect":"0",
"Option_01_Hint":null,
"Option_01_Hint_Media":null,
"Option_02":"Pituitary gland",
"Option_02_Media":null,
"Option_02_isCorrect":"1",
"Option_02_Hint":null,
"Option_02_Hint_Media":null,
"Option_03":"Amygdaloid body",
"Option_03_Media":null,
"Option_03_isCorrect":"0",
"Option_03_Hint":null,
"Option_03_Hint_Media":null,
"Option_04":"Basal ganglia ",
"Option_04_Media":null,
"Option_04_isCorrect":"0",
"Option_04_Hint":null,
"Option_04_Hint_Media":null,
"Option_05":null,
"Option_05_Media":null,
"Option_05_isCorrect":"0",
"Option_05_Hint":null,
"Option_05_Hint_Media":null,
"Option_06":null,
"Option_06_Media":null,
"Option_06_isCorrect":"0",
"Option_06_Hint":null,
"Option_06_Hint_Media":null,
"Added_By":"demo",
"Question_Type":"1",
"Created_At":"2015-03-07 22:59:15",
"Updated_At":"2015-03-14 21:42:12",
"DID":"0",
"Exams":null,
"Difficulty_Level":"1",
"isVerified":"0",
"isDuplicate":"0",
"isSeen":"0",
"isAnsweredCorrect":"0",
"isAnsweredWrong":"0",
"isMarked":"0",
"Remarks":null,
"isRepeat":"0",
"NotInExam":"0"
}
]

到目前为止，我的代码（点击按钮）是 -

Dim request As HttpWebRequest
Dim response As HttpWebResponse = Nothing
Dim reader As StreamReader
Dim rawresp As String
Dim URL As String
URL = "http://localhost/json/question.php"
Try
request = DirectCast(WebRequest.Create(URL), HttpWebRequest)
response = DirectCast(request.GetResponse(), HttpWebResponse)
reader = New StreamReader(response.GetResponseStream())
rawresp = reader.ReadToEnd()
'Everything works fine until here, but error occurs as soon as I write following code
Dim jsonQuestions As JSON_Questions = _
JsonConvert.DeserializeObject(Of JSON_Questions)(rawresp.ToString)

Catch ex As Exception
TextBox1.Text = ex.ToString
Finally
If Not response Is Nothing Then response.Close()
End Try

但它会引发以下错误 -

Newtonsoft.Json.JsonSerializationException：无法反序列化 当前 JSON 数组（例如 [1,2,3]）转换为类型 'Quiz_Maker.JSON_Questions' 因为该类型需要 JSON 对象 （例如 {"name":"value"}）正确反序列化。修复此错误 将 JSON 更改为 JSON 对象（例如 {"name":"value"}）或 将反序列化类型更改为数组或实现 集合接口（例如 ICollection、IList），例如 List 可以 从 JSON 数组反序列化。 JsonArrayAttribute 也可以 添加到类型以强制它从 JSON 数组反序列化。小路 ''，第 1 行，位置 1。在 Newtonsoft.Json.Serialization.JsonSerializerInternalReader.EnsureArrayContract(JsonReader 阅读器，类型 objectType，JsonContract 合同）在 Newtonsoft.Json.Serialization.JsonSerializerInternalReader.CreateList(JsonReader reader, Type objectType, JsonContract contract, JsonProperty member, 对象现有值，字符串 id) 在 Newtonsoft.Json.Serialization.JsonSerializerInternalReader.CreateValueInternal(JsonReader reader, Type objectType, JsonContract contract, JsonProperty member, JsonContainerContract containerContract, JsonProperty containerMember, 对象现有值）在 Newtonsoft.Json.Serialization.JsonSerializerInternalReader.Deserialize(JsonReader 阅读器，类型 objectType，布尔值 checkAdditionalContent）在 Newtonsoft.Json.JsonSerializer.DeserializeInternal（JsonReader 阅读器， 类型 objectType) 在 Newtonsoft.Json.JsonSerializer.Deserialize（JsonReader 阅读器，类型 objectType) 在 Newtonsoft.Json.JsonConvert.DeserializeObject(String 值，类型类型，JsonSerializerSettings 设置）在 Newtonsoft.Json.JsonConvert.DeserializeObject[T]（字符串值， JsonSerializerSettings 设置）在 Newtonsoft.Json.JsonConvert.DeserializeObject[T]（字符串值）在 Quiz_Maker.Advanced_Settings.btnResetQuestions_Click（对象发送者， C:\VisualStudioProjects\Quiz Maker\Quiz Maker\Quiz 中的 EventArgs e) Maker\Advanced Settings.vb:line 25

看了net和stackoverflow的类似问题后，我做了JSON_Questions类如下-

Public Class JSON_Questions
    Public Property QID() As String
        Get
            Return m_QID
        End Get
        Set(value As String)
            m_QID = value
        End Set
    End Property
    Private m_QID As String
    Public Property Question_Text() As String
        Get
            Return m_Question_Text
        End Get
        Set(value As String)
            m_Question_Text = value
        End Set
    End Property
    Private m_Question_Text As String
    Public Property Question_Media() As Object
        Get
            Return m_Question_Media
        End Get
        Set(value As Object)
            m_Question_Media = value
        End Set
    End Property
    Private m_Question_Media As Object
    Public Property Subject_Id() As String
        Get
            Return m_Subject_Id
        End Get
        Set(value As String)
            m_Subject_Id = value
        End Set
    End Property
    Private m_Subject_Id As String
    Public Property Subject_Name() As String
        Get
            Return m_Subject_Name
        End Get
        Set(value As String)
            m_Subject_Name = value
        End Set
    End Property
    Private m_Subject_Name As String
    Public Property Topic_Id() As String
        Get
            Return m_Topic_Id
        End Get
        Set(value As String)
            m_Topic_Id = value
        End Set
    End Property
    Private m_Topic_Id As String
    Public Property Topic_Name() As String
        Get
            Return m_Topic_Name
        End Get
        Set(value As String)
            m_Topic_Name = value
        End Set
    End Property
    Private m_Topic_Name As String
    Public Property Chapter_No() As String
        Get
            Return m_Chapter_No
        End Get
        Set(value As String)
            m_Chapter_No = value
        End Set
    End Property
    Private m_Chapter_No As String
    Public Property Exam_Id() As String
        Get
            Return m_Exam_Id
        End Get
        Set(value As String)
            m_Exam_Id = value
        End Set
    End Property
    Private m_Exam_Id As String
    Public Property Exam_Name() As String
        Get
            Return m_Exam_Name
        End Get
        Set(value As String)
            m_Exam_Name = value
        End Set
    End Property
    Private m_Exam_Name As String
    Public Property Explanation() As String
        Get
            Return m_Explanation
        End Get
        Set(value As String)
            m_Explanation = value
        End Set
    End Property
    Private m_Explanation As String
    Public Property Explanation_Media() As Object
        Get
            Return m_Explanation_Media
        End Get
        Set(value As Object)
            m_Explanation_Media = value
        End Set
    End Property
    Private m_Explanation_Media As Object
    Public Property Reference() As Object
        Get
            Return m_Reference
        End Get
        Set(value As Object)
            m_Reference = value
        End Set
    End Property
    Private m_Reference As Object
    Public Property Option_01() As String
        Get
            Return m_Option_01
        End Get
        Set(value As String)
            m_Option_01 = value
        End Set
    End Property
    Private m_Option_01 As String
    Public Property Option_01_Media() As Object
        Get
            Return m_Option_01_Media
        End Get
        Set(value As Object)
            m_Option_01_Media = value
        End Set
    End Property
    Private m_Option_01_Media As Object
    Public Property Option_01_isCorrect() As String
        Get
            Return m_Option_01_isCorrect
        End Get
        Set(value As String)
            m_Option_01_isCorrect = value
        End Set
    End Property
    Private m_Option_01_isCorrect As String
    Public Property Option_01_Hint() As String
        Get
            Return m_Option_01_Hint
        End Get
        Set(value As String)
            m_Option_01_Hint = value
        End Set
    End Property
    Private m_Option_01_Hint As String
    Public Property Option_01_Hint_Media() As Object
        Get
            Return m_Option_01_Hint_Media
        End Get
        Set(value As Object)
            m_Option_01_Hint_Media = value
        End Set
    End Property
    Private m_Option_01_Hint_Media As Object
    Public Property Option_02() As String
        Get
            Return m_Option_02
        End Get
        Set(value As String)
            m_Option_02 = value
        End Set
    End Property
    Private m_Option_02 As String
    Public Property Option_02_Media() As Object
        Get
            Return m_Option_02_Media
        End Get
        Set(value As Object)
            m_Option_02_Media = value
        End Set
    End Property
    Private m_Option_02_Media As Object
    Public Property Option_02_isCorrect() As String
        Get
            Return m_Option_02_isCorrect
        End Get
        Set(value As String)
            m_Option_02_isCorrect = value
        End Set
    End Property
    Private m_Option_02_isCorrect As String
    Public Property Option_02_Hint() As Object
        Get
            Return m_Option_02_Hint
        End Get
        Set(value As Object)
            m_Option_02_Hint = value
        End Set
    End Property
    Private m_Option_02_Hint As Object
    Public Property Option_02_Hint_Media() As Object
        Get
            Return m_Option_02_Hint_Media
        End Get
        Set(value As Object)
            m_Option_02_Hint_Media = value
        End Set
    End Property
    Private m_Option_02_Hint_Media As Object
    Public Property Option_03() As String
        Get
            Return m_Option_03
        End Get
        Set(value As String)
            m_Option_03 = value
        End Set
    End Property
    Private m_Option_03 As String
    Public Property Option_03_Media() As Object
        Get
            Return m_Option_03_Media
        End Get
        Set(value As Object)
            m_Option_03_Media = value
        End Set
    End Property
    Private m_Option_03_Media As Object
    Public Property Option_03_isCorrect() As String
        Get
            Return m_Option_03_isCorrect
        End Get
        Set(value As String)
            m_Option_03_isCorrect = value
        End Set
    End Property
    Private m_Option_03_isCorrect As String
    Public Property Option_03_Hint() As Object
        Get
            Return m_Option_03_Hint
        End Get
        Set(value As Object)
            m_Option_03_Hint = value
        End Set
    End Property
    Private m_Option_03_Hint As Object
    Public Property Option_03_Hint_Media() As Object
        Get
            Return m_Option_03_Hint_Media
        End Get
        Set(value As Object)
            m_Option_03_Hint_Media = value
        End Set
    End Property
    Private m_Option_03_Hint_Media As Object
    Public Property Option_04() As String
        Get
            Return m_Option_04
        End Get
        Set(value As String)
            m_Option_04 = value
        End Set
    End Property
    Private m_Option_04 As String
    Public Property Option_04_Media() As Object
        Get
            Return m_Option_04_Media
        End Get
        Set(value As Object)
            m_Option_04_Media = value
        End Set
    End Property
    Private m_Option_04_Media As Object
    Public Property Option_04_isCorrect() As String
        Get
            Return m_Option_04_isCorrect
        End Get
        Set(value As String)
            m_Option_04_isCorrect = value
        End Set
    End Property
    Private m_Option_04_isCorrect As String
    Public Property Option_04_Hint() As Object
        Get
            Return m_Option_04_Hint
        End Get
        Set(value As Object)
            m_Option_04_Hint = value
        End Set
    End Property
    Private m_Option_04_Hint As Object
    Public Property Option_04_Hint_Media() As Object
        Get
            Return m_Option_04_Hint_Media
        End Get
        Set(value As Object)
            m_Option_04_Hint_Media = value
        End Set
    End Property
    Private m_Option_04_Hint_Media As Object
    Public Property Option_05() As String
        Get
            Return m_Option_05
        End Get
        Set(value As String)
            m_Option_05 = value
        End Set
    End Property
    Private m_Option_05 As String
    Public Property Option_05_Media() As Object
        Get
            Return m_Option_05_Media
        End Get
        Set(value As Object)
            m_Option_05_Media = value
        End Set
    End Property
    Private m_Option_05_Media As Object
    Public Property Option_05_isCorrect() As String
        Get
            Return m_Option_05_isCorrect
        End Get
        Set(value As String)
            m_Option_05_isCorrect = value
        End Set
    End Property
    Private m_Option_05_isCorrect As String
    Public Property Option_05_Hint() As Object
        Get
            Return m_Option_05_Hint
        End Get
        Set(value As Object)
            m_Option_05_Hint = value
        End Set
    End Property
    Private m_Option_05_Hint As Object
    Public Property Option_05_Hint_Media() As Object
        Get
            Return m_Option_05_Hint_Media
        End Get
        Set(value As Object)
            m_Option_05_Hint_Media = value
        End Set
    End Property
    Private m_Option_05_Hint_Media As Object
    Public Property Option_06() As String
        Get
            Return m_Option_06
        End Get
        Set(value As String)
            m_Option_06 = value
        End Set
    End Property
    Private m_Option_06 As String
    Public Property Option_06_Media() As Object
        Get
            Return m_Option_06_Media
        End Get
        Set(value As Object)
            m_Option_06_Media = value
        End Set
    End Property
    Private m_Option_06_Media As Object
    Public Property Option_06_isCorrect() As String
        Get
            Return m_Option_06_isCorrect
        End Get
        Set(value As String)
            m_Option_06_isCorrect = value
        End Set
    End Property
    Private m_Option_06_isCorrect As String
    Public Property Option_06_Hint() As Object
        Get
            Return m_Option_06_Hint
        End Get
        Set(value As Object)
            m_Option_06_Hint = value
        End Set
    End Property
    Private m_Option_06_Hint As Object
    Public Property Option_06_Hint_Media() As Object
        Get
            Return m_Option_06_Hint_Media
        End Get
        Set(value As Object)
            m_Option_06_Hint_Media = value
        End Set
    End Property
    Private m_Option_06_Hint_Media As Object
    Public Property Added_By() As String
        Get
            Return m_Added_By
        End Get
        Set(value As String)
            m_Added_By = value
        End Set
    End Property
    Private m_Added_By As String
    Public Property Question_Type() As String
        Get
            Return m_Question_Type
        End Get
        Set(value As String)
            m_Question_Type = value
        End Set
    End Property
    Private m_Question_Type As String
    Public Property Created_At() As String
        Get
            Return m_Created_At
        End Get
        Set(value As String)
            m_Created_At = value
        End Set
    End Property
    Private m_Created_At As String
    Public Property Updated_At() As String
        Get
            Return m_Updated_At
        End Get
        Set(value As String)
            m_Updated_At = value
        End Set
    End Property
    Private m_Updated_At As String
    Public Property DID() As String
        Get
            Return m_DID
        End Get
        Set(value As String)
            m_DID = value
        End Set
    End Property
    Private m_DID As String
    Public Property Exams() As String
        Get
            Return m_Exams
        End Get
        Set(value As String)
            m_Exams = value
        End Set
    End Property
    Private m_Exams As String
    Public Property Difficulty_Level() As String
        Get
            Return m_Difficulty_Level
        End Get
        Set(value As String)
            m_Difficulty_Level = value
        End Set
    End Property
    Private m_Difficulty_Level As String
    Public Property isVerified() As String
        Get
            Return m_isVerified
        End Get
        Set(value As String)
            m_isVerified = value
        End Set
    End Property
    Private m_isVerified As String
    Public Property isDuplicate() As String
        Get
            Return m_isDuplicate
        End Get
        Set(value As String)
            m_isDuplicate = value
        End Set
    End Property
    Private m_isDuplicate As String
    Public Property isSeen() As String
        Get
            Return m_isSeen
        End Get
        Set(value As String)
            m_isSeen = value
        End Set
    End Property
    Private m_isSeen As String
    Public Property isAnsweredCorrect() As String
        Get
            Return m_isAnsweredCorrect
        End Get
        Set(value As String)
            m_isAnsweredCorrect = value
        End Set
    End Property
    Private m_isAnsweredCorrect As String
    Public Property isAnsweredWrong() As String
        Get
            Return m_isAnsweredWrong
        End Get
        Set(value As String)
            m_isAnsweredWrong = value
        End Set
    End Property
    Private m_isAnsweredWrong As String
    Public Property isMarked() As String
        Get
            Return m_isMarked
        End Get
        Set(value As String)
            m_isMarked = value
        End Set
    End Property
    Private m_isMarked As String
    Public Property Remarks() As Object
        Get
            Return m_Remarks
        End Get
        Set(value As Object)
            m_Remarks = value
        End Set
    End Property
    Private m_Remarks As Object
    Public Property isRepeat() As String
        Get
            Return m_isRepeat
        End Get
        Set(value As String)
            m_isRepeat = value
        End Set
    End Property
    Private m_isRepeat As String
    Public Property NotInExam() As String
        Get
            Return m_NotInExam
        End Get
        Set(value As String)
            m_NotInExam = value
        End Set
    End Property
    Private m_NotInExam As String
End Class

以前，我使用的类如下-

Public Class JSON_Questions
    Public QID As Integer
    Public Question_Text As String
    Public Subject_Id As Integer
    Public Subject_Name As String
    Public Topic_Id As Integer
    Public Topic_Name As String
    Public Chapter_No As Integer
    Public Exam_Id As Integer
    Public Exam_Name As String
    Public Explanation As String
    Public Option_01 As String
    Public Option_01_isCorrect As Integer
    Public Option_02 As String
    Public Option_02_isCorrect As Integer
    Public Option_03 As String
    Public Option_03_isCorrect As Integer
    Public Option_04 As String
    Public Option_04_isCorrect As Integer
    Public Option_05 As String
    Public Option_05_isCorrect As Integer
    Public Option_06 As String
    Public Option_06_isCorrect As Integer
    Public Added_By As String
    Public Question_Type As Integer
    Public Created_At As String
    Public Updated_At As String
    'Public Json_Result As String
End Class

我什至尝试过JObject 和List(of JToken) -

Dim jResults As JObject = JObject.Parse(rawresp)
Dim results As List(Of JToken) = jResults.Children().ToList()

但是，上述方法似乎都不起作用。 我被困在这里超过 2 天，但无法弄清楚如何反序列化这个 Json 并插入到 sqlite 表中。

Answer 1

错误信息的关键部分是：

将反序列化的类型更改为数组或实现集合接口（例如ICollection、IList）的类型，如List

这两种方法中的任何一种都可以很好地处理更正的数据：

' get a List<T>
Dim myQAs = JsonConvert.DeserializeObject(Of List(Of JSON_Questions))(jstr)

' deser to an array:
Dim myQAs = JsonConvert.DeserializeObject(Of JSON_Questions())(jstr)

发布的 Json 包含 两个 问题，这就是错误消息说它需要一个数组 r 列表的原因。现在，当反序列化时，它位于数组或列表中，具体取决于您使用的是哪一个，因此要访问您的数据：

thisQ = myQAs(0).Question_Text

输入点后，Intellisense 将显示该字段，您可以选择所需的内容。

如果 Option_01...etc 是 Option 的集合或数组，而不是一遍又一遍地拼写出来，整个事情会更容易处理。

Answer 2

这里是关键：

无法将当前 JSON 数组（例如 [1,2,3]）反序列化为类型 'Quiz_Maker.JSON_Questions' 因为该类型需要 JSON 对象

反序列化器需要一个 JSON 对象，但您传递的是一个 JSON 数组。只需删除开头和结尾的方括号，您的代码就应该开始工作了。

或者你也可以使用

Dim jResults As JArray = JArray.Parse(rawresp)

而不是

Dim jResults As JObject = JObject.Parse(rawresp)

希望这会有所帮助，尽管它未经测试。