Develop Reference

How can I parse json to a C# object (Class)?

I have JSON data that I need to parse from C# object.
this is JSON Example.
{
"types":
[
[
"tour_type",
[
["groups",1],
["individual",2]
]
]
]
}
Here are my C# classes that are meant to contain that data:
using System;
using Newtonsoft.Json;
namespace JsonDeserializationTest
{
[JsonProperty("types")]
public class Types
{
[JsonProperty]
public List<Type> Values {get;set;}
}
public class Type
{
[JsonProperty]
public string Key {get;set;}
[JsonProperty]
public List<Dictionary<string, int>> Values { get; set; }
}
}
It's not working now.
How can I fix it?

Use the JsonSerializer (System.Text.Json) object.
Code:
YourClass obj = JsonSerializer.Deserialize<YourClass>(jsonString);

Your json has a list of list of the object... but you are declaring only List of the object.
public class Types
{
[JsonProperty("types")]
public List<List<object>> Values { get; set; }
// ------ UPDATE: This can only be list of list of 'object' ------- \\
}
Also, you are using the JsonProperty on the class, which is not where that normally goes. You want to use that on the property of the class.
UPDATE:
You cannot use List<List<Type>> for the json you are getting, it can only be List<List<object>>. You have to use object because it can either be a string or a List<List<string>>. After you update your Types class, you can successfully deserialize the json above.
var obj = JsonConvert.DeserializeObject<Types>(json);
and based on your json definition, you can access tour_type by using the following code
types.Values.First()[0].ToString()
// output: tour_type
List<List<string>> data = JsonConvert.DeserializeObject<List<List<string>>>(types.Values.First()[1].ToString())
// data[0]
[0]: "groups"
[1]: "1"
// data[1]
[0]: "individual"
[1]: "2"
Since both of the items in the types are objects, you will either have to convert them to string or a list of list of strings or whatever object they actually are.

The JSON payload in the provided example is formatted quite strangely, especially since it contains seemingly unnecessary array nesting. A payload like this usually includes more nested objects (rather than a bunch of nested arrays). Additionally, it has a list of (string, int) pairs, which is semantically very similar to a Dictionary<string, int>, but the payload doesn't lend itself to that. It would be helpful to know where it is coming from (what context) to understand how it might change.
The example JSON brings up a few questions (that you may want to ask yourself):
Can the "types" array contain multiple entries (at its immediate nesting)?
Can the "tour_type" key name appear after the array of string, int pairs? Is it possible for an entry where no such name exists?
What other elements can exist in the arrays within "tour_type"?
Is it guaranteed that the most nested array will contain just a single (string, int) pair?
Similarly, it is hard to understand what the example C# class is trying to encapsulate. Is List<Dictionary<string, int>> necessary?
All that said, here's a solution using the built-in System.Text.Json library, that could work for you. You could write something similar using Newtonsoft.Json, if necessary. The solution assumes:
We can't change the JSON payload (and that the third party API response will always returns something that is structurally similar to the example)
We can only make minimal changes to the C# class object provided in the example
The solution creates and a JsonConverter<T> that uses the low-level Utf8JsonReader to manually parse and create the custom object. This is required since nested "[" are being used to delineate what should be objects rather than "{". The converter is then registered by annotating the class with the attribute. Now, simply call JsonSerializer.Deserialize, passing in the JSON payload.
public class Tours
{
[JsonPropertyName("types")]
public List<UserType> Types { get; set; }
}
// Annotate the type to register the converter to use
[JsonConverter(typeof(CustomUserTypeConverter))]
public class UserType
{
public string Key { get; set; }
public Dictionary<string, int> Values { get; set; }
}
// This will use the low-level reader to build up the UserType
public class CustomUserTypeConverter : JsonConverter<UserType>
{
// Extra structural validation was done for invalid/incomplete JSON
// which might be too strict or incorrect and hence might require adjustments.
public override UserType Read(ref Utf8JsonReader reader, Type typeToConvert, JsonSerializerOptions options)
{
var result = new UserType();
if (!reader.Read())
{
throw new JsonException("Incomplete JSON.");
}
if (reader.TokenType != JsonTokenType.EndArray)
{
result.Key = reader.GetString();
ReadAndValidate(ref reader, JsonTokenType.StartArray);
int depthSnapshot = reader.CurrentDepth;
var values = new Dictionary<string, int>();
do
{
reader.Read();
if (reader.TokenType != JsonTokenType.StartArray && reader.TokenType != JsonTokenType.EndArray)
{
throw new JsonException($"Invalid JSON payload. Expected Start or End Array. TokenType: {reader.TokenType}, Depth: {reader.CurrentDepth}.");
}
if (reader.CurrentDepth <= depthSnapshot)
{
break;
}
reader.Read();
if (reader.TokenType != JsonTokenType.EndArray)
{
string key = reader.GetString();
reader.Read();
int value = reader.GetInt32();
values.Add(key, value);
ReadAndValidate(ref reader, JsonTokenType.EndArray);
}
} while (true);
ReadAndValidate(ref reader, JsonTokenType.EndArray);
result.Values = values;
}
return result;
}
private void ReadAndValidate(ref Utf8JsonReader reader, JsonTokenType expectedTokenType)
{
bool readNext = reader.Read();
if (!readNext || reader.TokenType != expectedTokenType)
{
string message = readNext ?
$"Invalid JSON payload. TokenType: {reader.TokenType}, Depth: {reader.CurrentDepth}, Expected: {expectedTokenType}" :
$"Incomplete JSON. Expected: {expectedTokenType}";
throw new JsonException(message);
}
}
// Implement this method if you need to Serialize (i.e. write) the object
// back to JSON
public override void Write(Utf8JsonWriter writer, UserType value, JsonSerializerOptions options)
{
throw new NotImplementedException();
}
}
Here's how you would use the above converter to serialize the JSON string provided in the example, along with how to access the values.
public static Tours ParseJson(string json)
{
Tours tours = JsonSerializer.Deserialize<Tours>(json);
return tours;
}
public static void AccessValues(Tours tours)
{
foreach (UserType data in tours.Types)
{
string typeName = data.Key; // "tour_type"
foreach (KeyValuePair<string, int> pairs in data.Values)
{
string key = pairs.Key; // "groups" or "individual
int value = pairs.Value; // 1 or 2
}
}
}
For what it's worth, Visual Studio suggests the following C# class structure for the example JSON (which is similar to what #Jawad suggested):
public class Rootobject
{
public object[][] types { get; set; }
}
Hope that helps.

I couldn't figure out your JSON so I created an example with verified JSON.
Try this:
JSON:
{
"Items": [
{
"Name": "tour",
"Attributes": [
{
"Name": "groups",
"Value": 1
},
{
"Name": "individual",
"Value": 2
}
]
},
{
"Name": "demo",
"Attributes": [
{
"Name": "this is demo",
"Value": 3
},
{
"Name": "design pattern",
"Value": 99
}
]
}
]
}
Types foo = JsonSerializer.Deserialize<Types>(jsonString);
public class TypeAttribute
{
public string Name { get; set; }
public int Value { get; set; }
}
public class Type
{
private readonly ICollection<TypeAttribute> _attributes;
public Type()
{
_attributes = new Collection<TypeAttribute>();
}
public void AddAttributes(IEnumerable<TypeAttribute> attrs)
{
foreach(TypeAttribute ta in attrs)
{
_attributes.Add(ta);
}
}
public string Name { get; set; }
public IEnumerable<TypeAttribute> Attributes
{
get { return _attributes; }
set
{
foreach(TypeAttribute ta in value)
{
_attributes.Add(ta);
}
}
}
}
public class Types
{
ICollection<Type> _items;
public Types()
{
_items = new Collection<Type>();
}
public void AddItems(IEnumerable<Type> tps)
{
foreach (Type t in tps)
{
_items.Add(t);
}
}
public IEnumerable<Type> Items
{
get { return _items; }
set
{
foreach (Type t in value)
{
_items.Add(t);
}
}
}
}

Unable to handle Collection Deserealization Error

I'm trying to handle deresealize an object that does not comply with some of my classes. I wold like the code to execute and fail only on the invalid attributes but the deserealization method is returning a null Object.
I am using this method in a generic utility class that deserealizes some string to any given type.
From the test code, the error handler works correctly on invalid dates and other invalid types and returns the object with the default .NET initialization values.
If I change (or comment) the Items collection in the sub object, the code works.
string json = "{\"Id\":8,\"CreatedByUserId\":0,\"CreatedOnDate\":\"2019X-Y02Z-W06T18:A51:05.783\",\"LastModifiedByUserId\":1,\"LastModifiedOnDate\":\"2019-03-12T17:00:34.82\",\"OperationData\":{\"IsActive\":true,\"Items\":[{\"_Id\":1,\"Id_Value\":0,\"Id\":1},{\"_Id\":2,\"Id\":2},{\"Id\":1,\"IsDeleted\":false,\"Content\":{}}]}}";
TestType test = DeserealizeContent(json);
/*The convertion utility*/
private static TestType DeserealizeContent(string data)
{
var settings = new JsonSerializerSettings
{
NullValueHandling = NullValueHandling.Ignore,
MissingMemberHandling = MissingMemberHandling.Ignore,
Error = HandleDeserializationError
};
var r = JsonConvert.DeserializeObject<TestType>(data, settings);
return r;
}
public static void HandleDeserializationError(object sender, ErrorEventArgs errorArgs)
{
errorArgs.ErrorContext.Handled = true;
}
/*Supporting types*/
public class TestType {
public int Id { get; set; }
public DateTime CreatedOnDate { get; set; }
public int CreatedByUserId { get; set; }
public string Instructions { get; set; }
public OperationDataType OperationData {get;set;}
}
public class OperationDataType {
public bool IsActive { get; set; }
public List<int> Items { get; set; }
}
I was expecting the error handler to catch handle the exception and continue with the process but instead the deserealization just returns null in the end.
If I change List Items to List Items the result is correctly parsed.
My expected result wold be:
{
"Id": 8,
"CreatedByUserId": 0,
"CreatedOnDate": null,
"LastModifiedByUserId": 1,
"LastModifiedOnDate": "2019-03-12T17:00:34.82",
"OperationData": {
"IsActive": true,
"Items": null
}
}
EDIT - workaround
The suggestion from Yair (bellow) works.
Changing from List to List works as expected and the exception get handle correctly.

The items in your json is not an array of int so how you want it to be List?
Items is array of objects look at the json formated:
{
"Id": 8,
"CreatedByUserId": 0,
"CreatedOnDate": "2019X-Y02Z-W06T18:A51:05.783",
"LastModifiedByUserId": 1,
"LastModifiedOnDate": "2019-03-12T17:00:34.82",
"OperationData": {
"IsActive": true,
"Items": [{
"_Id": 1,
"Id_Value": 0,
"Id": 1
}, {
"_Id": 2,
"Id": 2
}, {
"Id": 1,
"IsDeleted": false,
"Content": {}
}
]
}
}
You can do one of three things:
handle the json content as string or map it so the items will be int array [1,2,3].
create item class for the items that include all the fields you need then extract the int that you want.
get it as object like you do now and use reflection () for getting the int you want.
you can use this function for reflection:
public static object GetPropValue(object src, string propName)
{
return src.GetType().GetProperty(propName).GetValue(src, null);
}
and then use it like this:
GetPropValue(test.OperationData.items[0], "Id")
EDIT
you can use this to deserialize the json in generic way:
Newtonsoft.Json.Linq.JObject jsonDeserialized = (Newtonsoft.Json.Linq.JObject)Newtonsoft.Json.JsonConvert.DeserializeObject<object>(json);
and then
you can map it manually or with automapper to the new TestType test that you want without the items in it.
you can get the values like this:
test.Id = jsonDeserialized["Id"];
test.CreatedByUserId = jsonDeserialized["CreatedByUserId"];
and so on
according to your last comment i find that if i changed the List<int> Items to List<long> Items it works as you wanted. it is something with primitive types and the parsing that deserialize do.

Adding a root element to json

I am generating a json string using NewtosoftJson using a table to format the the json. This is a simple key value pairs list and looks like:
public class items
{
private string key = String.Empty;
private string value = String.Empty;
public string Key
{
get
{
return key;
}
set
{
if (value != key)
{
key = value;
}
}
}
public string Value
{
get
{
return value;
}
set
{
if (value != this.value)
{
this.value = value;
}
}
}
}
When a list is populated and then serialised I get this JSON:
"Items": [
{
"Key":"FirstValue",
"Value":"One"
},
{
"Key":"SecondValue",
"Value":"Two"
},
{
"Key":"ThirdValue",
"Value":"Three"
}
]
What I need to get is:
"customData": {
"items": [
{
"Key":"FirstValue",
"Value":"One"
},
{
"Key":"SecondValue",
"Value":"Two"
},
{
"Key":"ThirdValue",
"Value":"Three"
}
]
}
I have tried creating a second class CustomData but can't see how to get the original JSON into the second class! Could you advice me on the correct way to construct the second class and method used to populate it please.

You can create an anonymous object and serialize that:
var objContainingItems = ... // your usual code
var customDataObj = new { customData = objContainingItems };
string json = JsonConvert.SerializeObject(customDataObj);
This is the most convenient solution if all you are interested in is serializing.
If you also want to be able to deserialize it, then you will need to use a class as specified in the answer by #William Moore.

Create a class customData and create a reference to the class items inside it. Then serialise your customData class using Newtonsoft.Json rather than your items class. So you will have:
public class CustomData
{
public items[] items; // I would rename the class items to item
}
Then you have an object of type customData, called customData which you pass into Newtonsoft.
You could then use the following to serialise/deserialise your data:
CustomData input = new CustomData();
input.items = []; // Whatever you have at the moment?
string json = JsonConvert.SerializeObject(account) //optionally set Formatting.Indented
CustomData deserialised = JsonConvert.DeserializeObject<CustomData>(json);

Deserialize JSON value without name

How can I deserialize a string in C# that only have values and no name. It looks like this: The problem is that this stream of string does not have name and uses array.
{
"result": {
"14400": [
[
1502985600,
262.18,
262.18,
257,
257,
1096.0131
],
[
1503000000,
257,
261.33,
254.8,
257,
1130.5897
]
],
"14405": [
[
1503014400,
258.03,
261.5,
257.01,
257.01,
520.7805
],
[
1503028800,
258,
260.98,
252.4,
259.56,
298.5658
],
]
]
}
}

Just create a class like
public class Root
{
public Dictionary<int,List<List<double>>> Result { get; set; }
}
and deserialize as
var res = JsonConvert.DeserializeObject<Root>(json);

I see it's an array, you could create a method to parse the class out of given JArray.
The Jason data
public void methpod()
{
string json ="Your jason value "
var factory = new Factory();
var suggest = factory.Create(json);
Console.WriteLine(suggest);
}
Make a class as suggested :
public class Factory
{
public Evan Create(string json)
{
var array = JArray.Parse(json);
string search = array[0].ToString();
string[] terms = array[1].ToArray().Select(item => item.ToString()).ToArray();
return new Evan{Search = search, Terms = terms};
}
}
and another
public class Evan
{
public string Search { get; set; }
public IEnumerable<string> Terms { get; set; }
public override string ToString()
{
return string.Format("Search={0},Terms=[{1}]",
Search, string.Join(",", Terms));
}
}

Tip
If you have JSON that you want to deserialize, and you don't have the class to deserialize it into, Visual Studio 2019 can automatically generate the class you need:
Copy the JSON that you need to deserialize.
Create a class file and delete the template code.
Choose Edit > Paste Special > Paste JSON as Classes.
The result is a class that you can use for your deserialization target

How to avoid fields when deserialize the JSON response directly into a strongly typed object?

I have a json response displayed as below. I am using datacontractserializer to serialize.
If I need only "text" and "created time" from this Json response...how should be my DataContract looks like?
Do I need to have all these six properties in my data contract ? and use "IgnoreDataMember" as attribute?
Also, do I need to give same name for my properties in datacontract (Ex : screenName, text as property name ?)
"abcDetails":[
{
"screenName":"my name",
"text":"tweet desc",
"createdTime":1423494304000,
"entities":{ },
"name":"abc",
"id":"123"
}]

To answer your questions:
You can omit properties that you do not need and DataContractJsonSerializer will skip over them.
You class's property names can differ from the JSON property names as long as you set the DataMemberAttribute.Name value to be the same as the name appearing in the JSON.
Your JSON is invalid, it is missing outer braces. I assume that's just a copy/paste error in your question.
Thus your classes could look like:
[DataContract]
public class Detail
{
[DataMember(Name="text")]
public string Text { get; set; }
[DataMember(Name="createdTime")]
public long CreatedTimeStamp { get; set; }
}
[DataContract]
public class RootObject
{
[DataMember(Name="abcDetails")]
public List<Detail> Details { get; set; }
}
And to test:
string json = #"
{
""abcDetails"":[
{
""screenName"":""my name"",
""text"":""tweet desc"",
""createdTime"":1423494304000,
""entities"":{ },
""name"":""abc"",
""id"":""123""
}]
}
";
var response = DataContractJsonSerializerHelper.GetObject<RootObject>(json);
foreach (var detail in response.Details)
{
Console.WriteLine(string.Format("Created Time: {0}; Text: \"{1}\"", detail.CreatedTimeStamp, detail.Text));
}
produces the output
Created Time: 1423494304000; Text: "tweet desc"
using the helper class:
public static class DataContractJsonSerializerHelper
{
public static T GetObject<T>(string json) where T : class
{
DataContractJsonSerializer serializer = new DataContractJsonSerializer(typeof(T));
return GetObject<T>(json, serializer);
}
public static T GetObject<T>(string json, DataContractJsonSerializer serializer)
{
using (var stream = GenerateStreamFromString(json))
{
var obj = serializer.ReadObject(stream);
return (T)obj;
}
}
private static MemoryStream GenerateStreamFromString(string value)
{
return new MemoryStream(Encoding.Unicode.GetBytes(value ?? ""));
}
}