When performing an AJAX request I am getting the following error:
Error converting value {null} to type 'System.Int32'. Path '[5].tabID', line 1, position 331.
The error occurs on the second line of my processRequest (...)
public void ProcessRequest (HttpContext context) {
string strJson = new StreamReader(context.Request.InputStream).ReadToEnd();
List<ElementToUpdate> elements = JsonConvert.DeserializeObject<List<ElementToUpdate>>(strJson);
// (...)
}
The debugger says that this the content of strJson
:
[{
"bmk": "132M1",
"state": "off",
"type": "motor",
"tabID": 8
}, {
"bmk": "158M1",
"state": "off",
"type": "motor",
"tabID": 8
}, {
"bmk": "194M1",
"state": "off",
"type": "motor",
"tabID": 8
}, {
"bmk": "198M1",
"state": "on",
"type": "motor",
"tabID": 8
}, {
"bmk": "202M1",
"state": "off",
"type": "motor",
"tabID": 8
}, {
"bmk": "test-m",
"state": "on",
"type": "motor",
"tabID": null
}, {
"bmk": "158M1-2",
"state": "off",
"type": "motor",
"tabID": 2
}, {
"bmk": "100M1",
"state": "on_right",
"type": "screwconveyor",
"tabID": 8
}, {
"bmk": "152M1",
"state": "on",
"type": "screwconveyor",
"tabID": 8
}, {
"bmk": "192M1",
"state": "on_left",
"type": "screwconveyor",
"tabID": 8
}, {
"bmk": "196M1",
"state": "off",
"type": "screwconveyor",
"tabID": 8
}, {
"bmk": "2000M1",
"state": "on_left",
"type": "screwconveyor",
"tabID": 8
}, {
"bmk": "74M1",
"state": "off",
"type": "screwconveyor",
"tabID": 8
}, {
"bmk": "76M1",
"state": "off",
"type": "screwconveyor",
"tabID": 8
}, {
"bmk": "80M1",
"state": "off",
"type": "screwconveyor",
"tabID": 8
}, {
"bmk": "82M1",
"state": "off",
"type": "screwconveyor",
"tabID": 8
}, {
"bmk": "86M1",
"state": "off",
"type": "screwconveyor",
"tabID": 8
}, {
"bmk": "90M1",
"state": "off",
"type": "screwconveyor",
"tabID": 8
}, {
"bmk": "94M1",
"state": "off",
"type": "screwconveyor",
"tabID": 8
}, {
"bmk": "95M1",
"state": "off",
"type": "screwconveyor",
"tabID": 8
}, {
"bmk": "96M1",
"state": "off",
"type": "screwconveyor",
"tabID": 8
}, {
"bmk": "102Y1",
"state": "closed",
"type": "ventile",
"tabID": 8
}, {
"bmk": "104Y1",
"state": "open",
"type": "ventile",
"tabID": 8
}, {
"bmk": "112Y2",
"state": "closed",
"type": "ventile",
"tabID": 8
}, {
"bmk": "114Y2",
"state": "closed",
"type": "ventile",
"tabID": 8
}, {
"bmk": "120Y1",
"state": "closed",
"type": "ventile",
"tabID": 8
}, {
"bmk": "122Y1",
"state": "closed",
"type": "ventile",
"tabID": 8
}, {
"bmk": "128Y2",
"state": "closed",
"type": "ventile",
"tabID": 8
}, {
"bmk": "146Y1_2",
"state": "closed",
"type": "ventile",
"tabID": 8
}, {
"bmk": "148Y2",
"state": "closed",
"type": "ventile",
"tabID": 8
}, {
"bmk": "156Y1",
"state": "closed",
"type": "ventile",
"tabID": 8
}, {
"bmk": "180Y1",
"state": "open",
"type": "ventile",
"tabID": 8
}, {
"bmk": "182Y1",
"state": "closed",
"type": "ventile",
"tabID": 8
}, {
"bmk": "184Y1",
"state": "open",
"type": "ventile",
"tabID": 8
}, {
"bmk": "206Y1",
"state": "open",
"type": "ventile",
"tabID": 8
}, {
"bmk": "208Y1",
"state": "closed",
"type": "ventile",
"tabID": 8
}, {
"bmk": "72Y2",
"state": "closed",
"type": "ventile",
"tabID": 8
}, {
"bmk": "78Y2",
"state": "open",
"type": "ventile",
"tabID": 8
}, {
"bmk": "84Y2",
"state": "closed",
"type": "ventile",
"tabID": 8
}, {
"bmk": "88Y2",
"state": "closed",
"type": "ventile",
"tabID": 8
}, {
"bmk": "92Y2",
"state": "closed",
"type": "ventile",
"tabID": 8
}, {
"bmk": "95_1Y1",
"state": "blocked",
"type": "ventile",
"tabID": 8
}, {
"bmk": "17H1",
"state": "on",
"type": "lamp",
"tabID": 8
}, {
"bmk": "l1",
"state": "on",
"type": "lamp",
"tabID": 8
}, {
"bmk": "17H1-2",
"state": "on",
"type": "lamp",
"tabID": 2
}, {
"bmk": "106M1",
"state": "on",
"type": "elevator",
"tabID": 8
}, {
"bmk": "154M1",
"state": "off",
"type": "elevator",
"tabID": 8
}, {
"bmk": "164M1",
"state": "off",
"type": "rotaryvalve",
"tabID": 8
}]
The class ElementToUpdate
is
public class ElementToUpdate
{
public ElementType type;
public String bmk;
public string state;
public int tabID;
public ElementToUpdate()
{
}
public ElementToUpdate(ElementType type, String bmk, string state, int tabID)
{
this.type = type;
this.bmk = bmk;
this.state = state;
this.tabID = tabID;
}
}
So my question is: How to resolve this issue? If I understand the error message correctly, then it says that tabID
of the 5th json object in the serialized array is null
. But as you can see it isn't. Moreover ElementToUpdate.tabID
isn't an Int32
but an int
. Did I miss something?
The solution
In fact, my JSON string contained an element whose tabID
was null
. I somehow overlooked this because firstly my JSON string wasn't formatted when I checked and secondly because [5] means "6th element of the array" (which I claimed to know actually).
See Question&Answers more detail:
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