I have a JSON string below:
{
"data": [
{
//data for first
},
{
//data for second
},
{
//data for third
},
]
}
From this JSON string, I would like to retrieve the number of objects within the "data" element, which in this case, would be 3.
What would be the best approach to accomplish this? I used the .Length property, but that returned a number that I did not expect.
I am using C#.
Since it's a string in C# you need to parse it into something you can use first. Here's a simple way using framework classes.
//obj is your JSON string
var serializer = new System.Web.Script.Serialization.JavaScriptSerializer();
Dictionary<string,object> csObj =
serializer.Deserialize<Dictionary<string,object>>(obj);
int length = ((ArrayList)csObj["data"]).Count;
When given a generic data structure, JavaScriptSerializer turns arrays into ArrayLists.
Here's an example using Newtonsoft.Json (Json.NET) which is available as a NuGet package.
Usage:
var jsonString = @"{
""data"": [
{
Name: ""Mike"", Age: 30
},
{
Name: ""John"", Age: 42
},
{
Name: ""Tom"", Age: 44
}
]
}";
var example = JsonConvert.DeserializeObject<Example>(jsonString);
// example.Data.Length == 3 at this point
Classes
class Example
{
public Person[] Data { get; set; }
}
class Person
{
public string Name { get; set; }
public int Age { get; set; }
}
You need to first deserialize your json string to get objects. The below post has a couple examples. After you deserialize you should have a collection of your data objects in c# (not a string). From there you should be able to call collection.Count or array.Length depending on what collection type you are using.
.Lengthwill give you the number of charachter in theString. To find the objects you will need to deserialise the JSON usingJavaScriptSerializerorDataContractJsonSerializer, both of which will require a compatible type. Alternatively you could use one of many third party assemblies or, roll your own deserialiser (not reccomended) or finally you could count the number of braces, accounting for opening, closing and nesting and deduce the count that way.