Convert json to datatable vb

Question

Good morning, today i was trying to convert my json to datatable.

This is what i\'m trying to do

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Answer 1

First you need to remove this line:

Dim json_jsonstring = Newtonsoft.Json.JsonConvert.SerializeObject(json_result)

The downloaded string is already JSON, if you serialize it again you will turn it into an escaped JSON string literal, whereupon deserializing it returns the string - and not a DataTable as you want. This explains the error Unexpected JSON token when reading DataTable. Expected StartArray, got String. Path '', line 1, position 9919: Json.NET parsed the entire json_jsonstring string as a single, escaped string literal.

Second, your JSON contains an outer root object like so:

{
  "Table": [
    {
      "IdOwner": "Davide", 
      // Additional properties
    },
    // Additional rows.
  ]
}

Thus you need to introduce a root object with the necessary Table property to deserialize the DataTable into. You can do it with the following generic root:

Class RootObject(Of T)
    Public Property Table As T
End Class

And then deserialize as follows:

Dim table = JsonConvert.DeserializeObject(Of RootObject(Of DataTable))(json_result).Table

Sample fiddle.

Or, if you don't care to create a root type, deserialize to a temporary Dictionary(Of string, DataTable):

Dim table = JsonConvert.DeserializeObject(Of Dictionary(Of string, DataTable))(json_result).Values.SingleOrDefault()

Sample fiddle #2:

You asked, I was wondering if making a sort of "substring" deleting the "{ Table:" part and the last } could work? Certainly it's possible but I would not recommend this. You would be manually duplicating some of the logic of a JSON parser. Let Json.NET do the work for you, it will handle whitespace and newlines correctly.