Error during serialization or deserialization. JSON JavaScriptSerializer

Question

I'm trying to retrieve images from my database, works fine with little images but when I try it with the Windows 7 default images (Desert, Koala, Penguins, Tulips, etc.) doesn't work and I get this error:

"Error during serialization or deserialization using the JSON JavaScriptSerializer. The length of the string exceeds the value set on the maxJsonLength property."

I modify my web.config with this:

<scripting>
  <webServices>
    <jsonSerialization maxJsonLength="2147483647"/>
  </webServices>
</scripting>

What I use to retrieve the images is this code:

public static byte[] Serialize(object obj)
{
    var binaryFormatter = new BinaryFormatter();
    var ms = new MemoryStream();
    binaryFormatter.Serialize(ms, obj);
    return ms.ToArray();
}


[WebMethod]
public string ObtenerImagen(int id)
{
    DataTable dt = new DataTable();        
    dt = conn.consultarImagen("alertas", id);
    Imagenes img;
    List<Imagenes> lista = new List<Imagenes>();

    for (int i = 0; i < dt.Rows.Count; i++)
    {
        img = new Imagenes();
        img.Id = Convert.ToInt32(dt.Rows[i]["Id"]);
        img.FileName = dt.Rows[i]["FileName"].ToString();
        img.Type = dt.Rows[i]["ContentType"].ToString();
        img.Content = Convert.ToBase64String(Serialize(dt.Rows[i]["Content"]));
        img.IdAlerta = Convert.ToInt32(dt.Rows[i]["IdAlerta"]);
        img.Pie = dt.Rows[i]["PieFoto"].ToString();
        //Llenado de lista
        lista.Add(img);
        img = null;
    }
    JavaScriptSerializer js = new JavaScriptSerializer();
    string lineas = js.Serialize(lista);
    return lineas;
}

And then I use this javascript function with ajax:

 success: function (data) {
        var aRC = JSON.parse(data.d);
        var lineas = "";

        for (var i = 0; i < aRC.length; i++) {
            var id = aRC[i].Id;
            var num = id;
            var rev = aRC[i].FileName;
            var pur = aRC[i].Type;
            var status = aRC[i].Content;
            var imagen = status.substring(36, status.length - 37);
            var owner = aRC[i].IdAlerta;
            var pie = aRC[i].Pie;

            lineas += '<div class="col-lg-3 col-md-4 col-xs-3 thumb marco">';
            lineas += '<a class="thumbnail" href="#">';
            lineas += '<img class="responsive" src="data:image/jpeg;base64,' + imagen + '" />';                    
            lineas += '<p class="text-justify" id="Pie' + i + '">' + pie + '</p>';
            lineas += '</a>';
            lineas += '<span class="btn btn-xs btn-success fa fa-pencil hidden-print" id="EditPie' + i + '"></span>';
            lineas += '<input type="text" class="form-control hidden hidden-print" id="PiePag' + i + '"> <span class="btn btn-xs btn-success fa fa-check hidden hidden-print" id="OkPie' + i + '"></span>';
            lineas += '</div>';
      }
      $('#Imagenes').html(lineas);

What can I do tho solve this? I don't have any idea.

EDIT: Works fine with 1 image, problem occurs when I try to show more than 1 image

No, is not MVC, it just HTML and C# WebService with AJAX calls and JavaScript. — Francisco Fernandez
– Francisco Fernandez, Commented Aug 4, 2016 at 15:27
Ah I see, apologies. It's a known caveat in MVC that the Web.Config maxJsonLength is essentially ignored and must be declared within code. I'll leave someone else to answer your question, as I don't have any other suggestion. Good luck! — Tyler Roper
– Tyler Roper, Commented Aug 4, 2016 at 15:29

Kevin B Burns · Accepted Answer · 2016-08-04 15:34:29Z

1

Try setting the max JSON length via the instance you created like this:

js.MaxJsonLength = Int32.MaxValue;

See if that makes a difference, how big are your objects that you are trying to shove into it? JSON doesn't perform as well with a list of large objects, might be easier to lazy load them via AJAX. If you look at large galleries, they tend to show a loading image while its in the background retrieving the specific object for the next items and so forth.

answered Aug 4, 2016 at 15:34

Kevin B Burns

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3 Comments

Francisco Fernandez Over a year ago

I edit this code: var js = new JavaScriptSerializer { MaxJsonLength = Int32.MaxValue }; string lineas = js.Serialize(lista); Apparently works fine at least I tried it with 4 images, thanks bro.

Kevin B Burns Over a year ago

That is great, do you have an avg. on the image sizes at all? I was under the impression that a service or MVC would ignore it from the web config file. I would check out lazy loading everything via ajax though seriously, it will give your users a better viewing exp.

Francisco Fernandez Over a year ago

Less than 2mb. Now I tried with more than 10 images and works fine! so the problem was that, the service was ignoring the web.config

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