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user2799017
user2799017

Reputation: 3

Newtonsoft.Json.JsonReaderException

I have a problem with Newtonsoft.Json. I'm trying to parse JSON from a URL but I'm getting an error. Here is the JSON:

[
    {
        "ID": "0",
        "Nome": "we",
        "Data": "2013-09-16",
        "Orario": "00:00:16",
        "Prestazione": "dfg",
        "Stato": "dfg",
        "Numero_Telefono": "dfg"
    },
    {
        "ID": "0",
        "Nome": "fg",
        "Data": "2013-09-26",
        "Orario": "00:00:00",
        "Prestazione": "",
        "Stato": "",
        "Numero_Telefono": ""
    },
    {
        "ID": "1",
        "Nome": "davide",
        "Data": "2013-09-26",
        "Orario": "00:00:16",
        "Prestazione": "ds",
        "Stato": "sd",
        "Numero_Telefono": "3546"
    }
]

Here is the code I am using:

Dim request As HttpWebRequest
Dim response As HttpWebResponse = Nothing
Dim reader As StreamReader

Try

    request = DirectCast(WebRequest.Create("http://nhd.altervista.org/connectDb.php"), HttpWebRequest)
    response = DirectCast(request.GetResponse(), HttpWebResponse)
    reader = New StreamReader(response.GetResponseStream())

    Dim rawresp As String
    rawresp = reader.ReadToEnd()

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

    For Each item As JProperty In results
        item.CreateReader()
        MsgBox(item.Value("img")) ' because my tag in json is img
    Next

Catch ex As Exception
    Console.WriteLine(ex.ToString)
    MsgBox(ex.ToString)
Finally
    If Not response Is Nothing Then response.Close()
End Try

This is the error I receive when I try to parse the JSON:

Newtonsoft.Json.JsonReaderException: Error reading JObject from JsonReader. Current JsonReader item is not an object: StartArray. Path '', line 1, position 1.

Can you help me solve this?

Upvotes: 0

Views: 9892

Answers (1)

Brian Rogers
Brian Rogers

Reputation: 129777

You are getting this error because you are using JObject.Parse, which expects a single JSON object, but your JSON contains an array. To correct this, use JArray.Parse instead.

But, there is another problem: the rest of your code is not set up to handle the results correctly. Because your results are an array of objects, your For Each loop needs to be expecting JObject items, not JProperty items. Once you have each item, you can then get the properties from them as needed.

I am not sure what you were trying to do with the item.CreateReader() line, as you are not doing anything with its return value, and you don't seem to need anyway. Similarly, I am also confused with your MsgBox(item.Value("img")) line, because there is no "img" property anywhere in the JSON. So this will always be null.

Here is some corrected code which will parse the JSON and display all the properties for each object in the results. This should give you a starting point to work with.

Dim request As HttpWebRequest
Dim response As HttpWebResponse = Nothing
Dim reader As StreamReader

Try

    request = DirectCast(WebRequest.Create("http://nhd.altervista.org/connectDb.php"), HttpWebRequest)
    response = DirectCast(request.GetResponse(), HttpWebResponse)
    reader = New StreamReader(response.GetResponseStream())

    Dim rawresp As String
    rawresp = reader.ReadToEnd()

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

    For Each item As JObject In results
        Dim demo As String = ""
        For Each prop As JProperty In item.Properties()
            demo = demo + prop.Name + " = " + prop.Value.ToString() + vbCrLf
        Next
        MsgBox(demo)
    Next

Catch ex As Exception
    Console.WriteLine(ex.ToString)
    MsgBox(ex.ToString)
Finally
    If Not response Is Nothing Then response.Close()
End Try

Upvotes: 4

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