Deserialize json array of array to List of string in C#

Question

I want to know how can I convert(Deserialize) a json array of json array to a list of string.

which means that inner array should be converted into string

the json is :

[
      [
         "a",
         "b",
         "c",
         null,
         1
      ],
      [
         "d",
         "e",
         null,
         2
      ]
]

the c# code using built-in c# json deserializer is :

List<string> myList = System.Text.Json.JsonSerializer.Deserialize<List<string>>(json);

This exception occurs :

And Newtonsoft :

List<string> myList = JsonConvert.DeserializeObject<List<string>>(json);

After I couldn't deserialize this json (which is google translate api response) with built-in deserializer in dotnetcore 3.1 and Newtonsoft , I decided to convert it manually to classes and strings but my code didn't work.

the result should be like that :

list :

item 1 :

[
        "a",
        "b",
        "c",
        null,
        1
]

item 2 :

[
        "d",
        "e",
        null,
        2
]

Is there a way to deserialize the json I mentioned in the link into classes ? (Visual Studio Special Paste didn't work)
Why I cannot convert json array of json array into List of string ?
Is this problem related with this issue ?

d, in json looks like a syntax error. 1 and 2 looks like int but not string. — aepot
– aepot, Commented Sep 20, 2020 at 18:42
Deserialize it into a nested collections (an array of string arrays, or something similar), and then walk through the results, adding each string to a list you create — Flydog57
– Flydog57, Commented Sep 20, 2020 at 18:43
@Parsa see the List<JArray> version in my answer. You can use Formatting.Indented to get multiline strings. — Guru Stron
– Guru Stron, Commented Sep 20, 2020 at 18:57

Guru Stron · Accepted Answer · 2020-09-20 18:53:20Z

2

You have not only string in your collection and you have nested arrays, so List<string> does not represent your JSON structure. If you want to get only string you can do something like this (this one is with Newtonsoft, after fixing the d value):

var strings = JsonConvert.DeserializeObject<List<List<object>>>(json)
    .Select(arr => arr.OfType<string>().ToList())
    .ToList();

Or using arr => arr.Select(a => a?.ToString() in Select if you want to convert all values to strings.

Or you can convert to List<JArray> with Newtonsoft and call ToString on it:

List<string> strings = JsonConvert.DeserializeObject<List<JArray>>(json)
    .Select(jarr => jarr.ToString(Newtonsoft.Json.Formatting.None)) 
    .ToList();
Console.WriteLine(string.Join(", ", strings)); // prints "["a","b","c",null,1], ["d","e",null,2]"

edited Sep 20, 2020 at 18:53

answered Sep 20, 2020 at 18:46

Guru Stron

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2 Comments

Parsa Over a year ago

your code works perfectly ! , thank you , do you know how can I make a c# class model for the json I provided in that link ? the visual studio couldn't do that. online sites couldn't too.

Guru Stron Over a year ago

@Parsa I'm afraid only something similar to List<List<object>> or List<JArray> or List<JToken> or just JToken with next manual handling. TBH it looks like somebody used arrays in few places where JSON object should be.

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