how to get json property name

Question

I have a class like following:

public class Client {
    [JsonProperty("first_name")]
    public string FirstName { get; set; }
    [JsonProperty("last_name")]
    public string LastName { get; set; }
}

using the following code I can get the properties and values in a dictionary of that class object:

var propertyValuesByName = client.GetType().GetProperties()
        .Where(pi => pi.PropertyType == typeof(string))         
        .Select(pi => new { Val = (string) pi.GetValue(client), Name = pi.Name })
        .ToDictionary(pi => pi.Name, pi => pi.Val);

so the dictionary contains property name as key and the property value as value. But what I want is, get the dictionary which key will be the object JsonProperty name instead of the real property name, means instead of "FirstName" I want "first_name" as key. How can I modify the above code to achieve this?

Can you please add sample JSON here you mention? – Sachith Wickramaarachchi Jan 06 '23 at 14:41 — Sachith Wickramaarachchi, Jan 06 '23 at 14:41

score 4 · Answer 1 · answered Jan 06 '23 at 15:13

To get the property name of a JSON object in C#, you can use the nameof operator. For example, given the following JSON object:

{
  "name": "John Smith",
  "age": 30,
  "city": "New York"
}

You can use the nameof operator to get the property names like this:

string name = nameof(jsonObject.name);  // "name"
string age = nameof(jsonObject.age);   // "age"
string city = nameof(jsonObject.city); // "city"

Note that the nameof operator only works with compile-time constants, so it will not work with dynamically generated property names.

Alternatively, you can use the JsonPropertyAttribute to specify the property name in the JSON object. For example: public class Person

{
  [JsonProperty("name")]
  public string Name { get; set; }

  [JsonProperty("age")]
  public int Age { get; set; }

  [JsonProperty("city")]
  public string City { get; set; }
}

you can then use reflection to get the property names like this: var person = new Person { Name = "John Smith", Age = 30, City = "New York" };

foreach (var property in person.GetType().GetProperties())
{

  var jsonPropertyAttribute = property.GetCustomAttribute<JsonPropertyAttribute>();
  if (jsonPropertyAttribute != null)
  {
    string propertyName = jsonPropertyAttribute.PropertyName;
  }
}

score 1 · Accepted Answer · answered Jan 06 '23 at 14:44

Use some more reflection to ger info from custom attribute:

.Select(pi => new 
{ 
    Val = (string) pi.GetValue(client), 
    Name = pi.GetCustomAttribute<JsonPropertyAttribute>()?.PropertyName ?? pi.Name
})

Or :

.Select(pi => new 
{ 
    Val = (string) pi.GetValue(client), 
    Name = (pi.GetCustomAttribute(typeof(JsonPropertyAttribute)) as JsonPropertyAttribute)?.PropertyName ?? pi.Name
})

Also note that if your object contains only string you can deserialize directly to Dictionary<string, string>.

it worked. thanks for your answer, regarding your suggestion I cant just deserialize the object as I want to remove null properties as well. — Fazla Elahi Md Jubayer, Jan 06 '23 at 15:06

score 0 · Answer 3 · answered Jan 06 '23 at 15:10

I guess it's similar to the problem exposed in this thread : How to get Json Property name using reflection in C#

If it's not mandatory for you to access object using reflection, you can just deserialize a Json to a Dictionary<string,string> like this :

var values = JsonConvert.DeserializeObject<Dictionary<string, string>>(json);

and then get the keys out of it using values.Keys. Hope this helps

how to get json property name

3 Answers3