How to check if a nested path exists in json object for C#?

Question

say wanted to check if a path "L1.L2.L3" exists in a json object. There is a way to check the levels step by step (How to check whether json object has some property), but I wish to save the trouble, and check the path instead.

before serialization or after ? need to parse json string or serialized object — Z.R.T.
– Z.R.T., Commented Sep 5, 2018 at 5:34
check out these two: 1. newtonsoft.com/json/help/html/QueryJsonSelectTokenJsonPath.htm . 2. stackoverflow.com/questions/19892617/… — NeverHopeless
– NeverHopeless, Commented Sep 5, 2018 at 5:49

Access Denied · Accepted Answer · 2018-09-05 05:36:01Z

9

You can use SelectToken method from newtonsoft.json (token is null, when no match found):

    string json = @"
{
    ""car"": {
        ""type"": {
            ""sedan"": {
                ""make"": ""honda"",
                ""model"": ""civics""
            }
        },                
    }
}";

    JObject obj = JObject.Parse(json);
    JToken token = obj.SelectToken("car.type.sedan.make",errorWhenNoMatch:false);
    Console.WriteLine(token.Path + " -> " + token?.ToString());

answered Sep 5, 2018 at 5:36

Access Denied

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2 Comments

robs Over a year ago

this will also return null if the path exists but the value of the property is null or empty string

robs Over a year ago

If you need SelectToken to identify missing tokens when null is a possible value (such as "myProp" : "" or "myProp" : null) then you must set 'errorWhenNoMatch : true)

liang · Accepted Answer · 2018-09-05 07:29:07Z

4

I ended up using a extension method like so:

public static bool PathExists(this JObject obj, string path)
{
    var tokens = obj.SelectTokens(path);
    return tokens.Any();
}

But the spirit is the same as the accepted answer.

answered Sep 5, 2018 at 7:29

liang

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