ackacky.bashmachckin ackacky.bashmachckin - 2 months ago 13
JSON Question

newtonsoft json deserialization error handling: partial deserialization

Is there way to deserialize invalid json?

For example, next JSON deserialization will fail with

JsonReaderException


{
'sessionId': 's0j1',
'commandId': 19,
'options': invalidValue // invalid value
}


because
options
property value is invalid.

Is there a nice way to get
sessionId
and
commandId
values even if
options
value is invalid?

I know it's possible to handle errors during deserialization (http://www.newtonsoft.com/json/help/html/SerializationErrorHandling.htm)

var json = "{'sessionId': 's0j1', 'commandId': 19, 'options': invalidValue}";

var settings = new JsonSerializerSettings
{
Error = delegate(object sender, ErrorEventArgs args)
{
args.ErrorContext.Handled = true;
}
});
var result = JsonConvert.DeserializeObject(json, settings);


Bit it will result in
result = null
.

Answer

You can do it with JsonReader.

Example code:

var result = new Dictionary<string, object>();

using (var reader = new JsonTextReader(new StringReader(yourJsonStr))
{
    var lastProp = string.Empty;
    try
    {
        while (reader.Read())
        {
            if (reader.TokenType == JsonToken.PropertyName)
            {
                lastProp = reader.Value.ToString();
            }

            if (reader.TokenType == JsonToken.Integer || 
                reader.TokenType == JsonToken.String)
            {
                result.Add(lastProp, reader.Value);
            }
        }
    }
    catch(JsonReaderException jre)
    {
        //do anything what you want with exception
    }
}

Note, that there is try..catch block as when JsonReader meets invalid character it throws JsonReaderException on reader.Read()

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