Sample class:
public class ClassA
{
public int Id { get; set; }
public string SomeString { get; set; }
public int? SomeInt { get; set; }
}
Default deserializer:
var myObject = JsonConvert.DeserializeObject<ClassA>(str);
Create the same object for two different inputs
{"Id":5}
or
{"Id":5,"SomeString":null,"SomeInt":null}
How can I track properties that were missing during deserialization process and preserve the same behavior? Is there a way to override some of JSON.net serializer methods (e.g. DefaultContractResolver class methods) to achive this. For example:
List<string> missingProps;
var myObject = JsonConvert.DeserializeObject<ClassA>(str, settings, missingProps);
For the first input list should contains the names of the missing properties ("SomeString", "SomeInt") and for second input it should be empty. Deserialized object remains the same.
1. JSON has a property which is missing in your class
Using property JsonSerializerSettings.MissingMemberHandling you can say whether missing properties are handled as errors.
Than you can install the Error delegate which will register errors.
This will detect if there is some "garbage" property in JSON string.
public class ClassA
{
public int Id { get; set; }
public string SomeString { get; set; }
}
internal class Program
{
private static void Main(string[] args)
{
const string str = "{'Id':5, 'FooBar': 42 }";
var myObject = JsonConvert.DeserializeObject<ClassA>(str
, new JsonSerializerSettings
{
Error = OnError,
MissingMemberHandling = MissingMemberHandling.Error
});
Console.ReadKey();
}
private static void OnError(object sender, ErrorEventArgs args)
{
Console.WriteLine(args.ErrorContext.Error.Message);
args.ErrorContext.Handled = true;
}
}
2. Your class has a property which is missing in JSON
Option 1:
Make it a required property:
public class ClassB
{
public int Id { get; set; }
[JsonProperty(Required = Required.Always)]
public string SomeString { get; set; }
}
Option 2:
Use some "special" value as a default value and check afterwards.
public class ClassB
{
public int Id { get; set; }
[DefaultValue("NOTSET")]
public string SomeString { get; set; }
public int? SomeInt { get; set; }
}
internal class Program
{
private static void Main(string[] args)
{
const string str = "{ 'Id':5 }";
var myObject = JsonConvert.DeserializeObject<ClassB>(str
, new JsonSerializerSettings
{
DefaultValueHandling = DefaultValueHandling.Populate
});
if (myObject.SomeString == "NOTSET")
{
Console.WriteLine("no value provided for property SomeString");
}
Console.ReadKey();
}
}
Option 3:
Another good idea would be to encapsulate this check iside the class istself. Create a Verify() method as shown below and call it after deserialization.
public class ClassC
{
public int Id { get; set; }
[DefaultValue("NOTSET")]
public string SomeString { get; set; }
public int? SomeInt { get; set; }
public void Verify()
{
if (SomeInt == null ) throw new JsonSerializationException("SomeInt not set!");
if (SomeString == "NOTSET") throw new JsonSerializationException("SomeString not set!");
}
}
Another way to find null/undefined tokens during De-serialization is to write a custom JsonConverter , Here is an example of custom converter which can report both omitted tokens (e.g. "{ 'Id':5 }") and null tokens (e.g {"Id":5,"SomeString":null,"SomeInt":null})
public class NullReportConverter : JsonConverter
{
private readonly List<PropertyInfo> _nullproperties=new List<PropertyInfo>();
public bool ReportDefinedNullTokens { get; set; }
public IEnumerable<PropertyInfo> NullProperties
{
get { return _nullproperties; }
}
public void Clear()
{
_nullproperties.Clear();
}
public override bool CanConvert(Type objectType)
{
return true;
}
public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer)
{
existingValue = existingValue ?? Activator.CreateInstance(objectType, true);
var jObject = JObject.Load(reader);
var properties =
objectType.GetProperties(BindingFlags.Instance | BindingFlags.Public | BindingFlags.NonPublic);
foreach (var property in properties)
{
var jToken = jObject[property.Name];
if (jToken == null)
{
_nullproperties.Add(property);
continue;
}
var value = jToken.ToObject(property.PropertyType);
if(ReportDefinedNullTokens && value ==null)
_nullproperties.Add(property);
property.SetValue(existingValue, value, null);
}
return existingValue;
}
//NOTE: we can omit writer part if we only want to use the converter for deserializing
public override void WriteJson(JsonWriter writer, object value, JsonSerializer serializer)
{
var objectType = value.GetType();
var properties =
objectType.GetProperties(BindingFlags.Instance | BindingFlags.Public | BindingFlags.NonPublic);
writer.WriteStartObject();
foreach (var property in properties)
{
var propertyValue = property.GetValue(value, null);
writer.WritePropertyName(property.Name);
serializer.Serialize(writer, propertyValue);
}
writer.WriteEndObject();
}
}
Note: we can omit the Writer part if we don't need to use it for serializing objects.
Usage Example:
class Foo
{
public int Id { get; set; }
public string SomeString { get; set; }
public int? SomeInt { get; set; }
}
class Program
{
static void Main(string[] args)
{
var nullConverter=new NullReportConverter();
Console.WriteLine("Pass 1");
var obj0 = JsonConvert.DeserializeObject<Foo>("{\"Id\":5, \"Id\":5}", nullConverter);
foreach(var p in nullConverter.NullProperties)
Console.WriteLine(p);
nullConverter.Clear();
Console.WriteLine("Pass2");
var obj1 = JsonConvert.DeserializeObject<Foo>("{\"Id\":5,\"SomeString\":null,\"SomeInt\":null}" , nullConverter);
foreach (var p in nullConverter.NullProperties)
Console.WriteLine(p);
nullConverter.Clear();
nullConverter.ReportDefinedNullTokens = true;
Console.WriteLine("Pass3");
var obj2 = JsonConvert.DeserializeObject<Foo>("{\"Id\":5,\"SomeString\":null,\"SomeInt\":null}", nullConverter);
foreach (var p in nullConverter.NullProperties)
Console.WriteLine(p);
}
}
I got this problem, but defaultValue was not solution due to POCO object. I think this is simpler approach than NullReportConverter.
There are three unit tests. Root is class that encapsulate whole json. Key is type of the Property. Hope this helps someone.
using Microsoft.VisualStudio.TestTools.UnitTesting;
using Newtonsoft.Json;
namespace SomeNamespace {
[TestClass]
public class NullParseJsonTest {
[TestMethod]
public void TestMethod1()
{
string slice = "{Key:{guid:\"asdf\"}}";
var result = JsonConvert.DeserializeObject<Root>(slice);
Assert.IsTrue(result.OptionalKey.IsSet);
Assert.IsNotNull(result.OptionalKey.Value);
Assert.AreEqual("asdf", result.OptionalKey.Value.Guid);
}
[TestMethod]
public void TestMethod2()
{
string slice = "{Key:null}";
var result = JsonConvert.DeserializeObject<Root>(slice);
Assert.IsTrue(result.OptionalKey.IsSet);
Assert.IsNull(result.OptionalKey.Value);
}
[TestMethod]
public void TestMethod3()
{
string slice = "{}";
var result = JsonConvert.DeserializeObject<Root>(slice);
Assert.IsFalse(result.OptionalKey.IsSet);
Assert.IsNull(result.OptionalKey.Value);
}
}
class Root {
public Key Key {
get {
return OptionalKey.Value;
}
set {
OptionalKey.Value = value;
OptionalKey.IsSet = true; // This does the trick, it is never called by JSON.NET if attribute missing
}
}
[JsonIgnore]
public Optional<Key> OptionalKey = new Optional<Key> { IsSet = false };
};
class Key {
public string Guid { get; set; }
}
class Optional<T> {
public T Value { get; set; }
public bool IsSet { get; set; }
}
}
Related
Some of my actions accept models like:
public class PaymentRequest
{
public decimal Amount { get; set; }
public bool? SaveCard { get; set; }
public int? SmsCode { get; set; }
public BankCardDetails Card { get; set; }
}
public class BankCardDetails
{
public string Number { get; set; }
public string HolderName { get; set; }
public string ExpiryDate { get; set; }
public string ValidationCode { get; set; }
}
And the action method looks like:
[HttpPost]
[Route("api/v1/payment/pay")]
public Task<BankCardActionResponse> Pay([FromBody] PaymentRequest request)
{
if (request == null)
throw new HttpResponseException(HttpStatusCode.BadRequest);
return _paymentService.PayAsync(DataUserHelper.PhoneNumber, request);
}
I use Nlog. I think it's clear this is a bad idea to log all this bank data. My log config file contained the following line:
<attribute name="user-requestBody" layout="${aspnet-request-posted-body}"/>
I logged the request. I decided to refactor that and planned the following strategy. Actions that contain sensitive data into their requests I will mark with an attribute like
[RequestMethodFormatter(typeof(PaymentRequest))]
then take a look at my custom renderer:
[LayoutRenderer("http-request")]
public class NLogHttpRequestLayoutRenderer : AspNetRequestPostedBody
{
protected override void DoAppend(StringBuilder builder, LogEventInfo logEvent)
{
base.DoAppend(builder, logEvent);
var body = builder.ToString();
// Get attribute of the called action.
var type = ... // How can I get "PaymentRequest" from the [RequestMethodFormatter(typeof(PaymentRequest))]
var res = MaskHelper.GetMaskedJsonString(body, type);
// ... and so on
}
}
I think you understand the idea. I need the type from the method's RequestMethodFormatter attribute. Is it even possible to get it into the renderer? I need it because I'm going to deserialize request JSON into particular models (it's gonna be into the MaskHelper.GetMaskedJsonString), work with the models masking the data, serialize it back into JSON.
So, did I choose a wrong approach? Or it's possible to get the type from the attribute into the renderer?
After some research, I ended up with the following solution:
namespace ConsoleApp7
{
internal class Program
{
private static void Main()
{
var sourceJson = GetSourceJson();
var userInfo = JsonConvert.DeserializeObject(sourceJson, typeof(User));
Console.WriteLine("----- Serialize without Resolver-----");
Console.WriteLine(JsonConvert.SerializeObject(userInfo));
Console.WriteLine("----- Serialize with Resolver-----");
Console.WriteLine(JsonConvert.SerializeObject(userInfo, new JsonSerializerSettings
{
ContractResolver = new MaskPropertyResolver()
}));
}
private static string GetSourceJson()
{
var guid = Guid.Parse("3e92f0c4-55dc-474b-ae21-8b3dac1a0942");
return JsonConvert.SerializeObject(new User
{
UserId = guid,
Age = 19,
Name = "John",
BirthDate = new DateTime(1990, 5, 12),
Hobbies = new[]
{
new Hobby
{
Name = "Football",
Rating = 5,
DurationYears = 3,
},
new Hobby
{
Name = "Basketball",
Rating = 7,
DurationYears = 4,
}
}
});
}
}
public class User
{
[MaskGuidValue]
public Guid UserId { get; set; }
[MaskStringValue("***")] public string Name { get; set; }
public int Age { get; set; }
[MaskDateTimeValue]
public DateTime BirthDate { get; set; }
public Hobby[] Hobbies { get; set; }
}
public class Hobby
{
[MaskStringValue("----")]
public string Name { get; set; }
[MaskIntValue(replacement: 11111)]
public int Rating { get; set; }
public int DurationYears { get; set; }
}
public class MaskPropertyResolver : DefaultContractResolver
{
protected override IList<JsonProperty> CreateProperties(Type type, MemberSerialization memberSerialization)
{
var props = base.CreateProperties(type, memberSerialization);
var allowedPropertyTypes = new Type[]
{
typeof(Guid),
typeof(DateTime),
typeof(string),
typeof(int),
};
foreach (var prop in props.Where(p => allowedPropertyTypes.Contains(p.PropertyType)))
{
if (prop.UnderlyingName == null)
continue;
var propertyInfo = type.GetProperty(prop.UnderlyingName);
var attribute =
propertyInfo?.GetCustomAttributes().FirstOrDefault(x => x is IMaskAttribute) as IMaskAttribute;
if (attribute == null)
{
continue;
}
if (attribute.Type != propertyInfo.PropertyType)
{
// Log this case, cause somebody used wrong attribute
continue;
}
prop.ValueProvider = new MaskValueProvider(propertyInfo, attribute.Replacement, attribute.Type);
}
return props;
}
private class MaskValueProvider : IValueProvider
{
private readonly PropertyInfo _targetProperty;
private readonly object _replacement;
private readonly Type _type;
public MaskValueProvider(PropertyInfo targetProperty, object replacement, Type type)
{
_targetProperty = targetProperty;
_replacement = replacement;
_type = type;
}
public object GetValue(object target)
{
return _replacement;
}
public void SetValue(object target, object value)
{
_targetProperty.SetValue(target, value);
}
}
}
[AttributeUsage(AttributeTargets.Property)]
public class MaskStringValueAttribute : Attribute, IMaskAttribute
{
public Type Type => typeof(string);
public object Replacement { get; }
public MaskStringValueAttribute(string replacement)
{
Replacement = replacement;
}
}
[AttributeUsage(AttributeTargets.Property)]
public class MaskIntValueAttribute : Attribute, IMaskAttribute
{
public object Replacement { get; }
public Type Type => typeof(int);
public MaskIntValueAttribute(int replacement)
{
Replacement = replacement;
}
}
[AttributeUsage(AttributeTargets.Property)]
public class MaskGuidValueAttribute : Attribute, IMaskAttribute
{
public Type Type => typeof(Guid);
public object Replacement => Guid.Empty;
}
[AttributeUsage(AttributeTargets.Property)]
public class MaskDateTimeValueAttribute : Attribute, IMaskAttribute
{
public Type Type => typeof(DateTime);
public object Replacement => new DateTime(1970, 1, 1);
}
public interface IMaskAttribute
{
Type Type { get; }
object Replacement { get; }
}
}
I hope somebody will find it helpful.
You can try nuget package https://www.nuget.org/packages/Slin.Masking and https://www.nuget.org/packages/Slin.Masking.NLog.
It can easily be integrated with DotNet projects with slight changes, and you can define your rules for it. But the document needs some improvement.
As a suggestion, you can use two files:
masking.json (can be a generic one, that shared across all projects)
masking.custom.json (can be used with particular rules for specific projects)
I have an Azure Server-less Function that serves to take in a JSON payload and work on the records contained. The function works perfectly well to do what is intended except it shouldn't matter the wrapper node name. For example:
{
"Wrapper": [{
"Field1": "Apple",
"Field2": "Peach",
"Field3": "########5",
"Field4": "Kiwi",
}]
}
Should be processed the same way as:
{
"OtherWrapperName": [{
"Column1": "Apple",
"Something": "Peach",
"SomethingElse": "Banana",
"Field4": "Kiwi"
}]
}
Right now it seems to expect the top level node to be called "Wrapper". Here is my attempt at this (some code has been redacted as it was unnecessary for this example):
public static async Task<HttpResponseMessage> Run(HttpRequestMessage req, TraceWriter log)
{
string InputData = await req.Content.ReadAsStringAsync();
var inputData = JsonConvert.DeserializeObject<ItemsPayload>(InputData);
var propertiesLookup = new Dictionary<string, ItemUpdate>();
var propertiesRequest = new PropertySearchRequest { Registry = new List<RequestPropertySearch>() };
int recordCounter = 0;
foreach (var item in inputData.Wrapper)
{
foreach (var kvp in item.Where(property => property.Value.StartsWith("#!!!#")))
{
propertiesLookup[recordCounter.ToString() + "|" + kvp.Value] = new ItemUpdate
{
Properties = item,
UpdateKey = kvp.Key
};
propertiesRequest.Registry.Add(new RequestPropertySearch
{
Token = kvp.Value
});
recordCounter++;
}
}
var intermediateRequest = JsonConvert.SerializeObject(propertiesRequest, Formatting.Indented);
HttpResponseMessage response = MakeRequest(serviceUrl, intermediateRequest, securityHeaderName, securityHeaderValue);
var responseBodyAsText = response.Content.ReadAsStringAsync();
var intermediateData = JsonConvert.DeserializeObject<PropertySearchResponse>(responseBodyAsText.Result);
recordCounter = 0;
foreach (var item in intermediateData.Registry)
{
if (item.Value != null)
{
var itemToUpdate = propertiesLookup[recordCounter.ToString() + "|" + item.Token];
itemToUpdate.Properties[itemToUpdate.UpdateKey] = item.Value;
if (directive.ToLower() == "s")
{
itemToUpdate.Properties[$"#{itemToUpdate.UpdateKey}"] = item.Token;
}
// recordCounter++;
}
recordCounter++;
}
var result = JsonConvert.SerializeObject(inputData, Formatting.Indented);
//return req.CreateResponse(HttpStatusCode.OK, "");
return new HttpResponseMessage()
{
Content = new StringContent(result, System.Text.Encoding.UTF8, "application/json")
};
}
Models:
public class ItemsPayload
{
//public string Directive { get; set; }
public List<Dictionary<string, string>> Wrapper { get; set; }
}
public class PropertySearchRequest
{
public List<RequestPropertySearch> Registry { get; set; }
}
public class RequestPropertySearch
{
public string Token { get; set; }
}
public class PropertySearchResponse
{
public List<ResponsePropertySearch> Registry { get; set; }
}
public class ResponsePropertySearch
{
public string Token { get; set; }
public string Value { get; set; }
public string ProcessId { get; set; }
public string Code { get; set; }
public string Remote { get; set; }
public string Message { get; set; }
}
public class ItemUpdate
{
public Dictionary<string, string> Properties { get; set; }
public string UpdateKey { get; set; }
}
I think the ItemsPayload class property "Wrapper" is causing this as if you change that to something else and rename the node in the JSON it works fine, but I want it to be independent of the name of the top level node. Any thoughts?
You could create a simple JsonConverter for your ItemsPayload to handle the varying wrapper name.
public class ItemsPayloadConverter : JsonConverter
{
public override bool CanConvert(Type objectType)
{
return objectType == typeof(ItemsPayload);
}
public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer)
{
JObject obj = JObject.Load(reader);
ItemsPayload payload = new ItemsPayload();
// Get the first property of the outer JSON object regardless of its name
// and populate the payload from it
JProperty wrapper = obj.Properties().FirstOrDefault();
if (wrapper != null)
{
payload.Wrapper = wrapper.Value.ToObject<List<Dictionary<string, string>>>(serializer);
}
return payload;
}
public override bool CanWrite
{
get { return false; }
}
public override void WriteJson(JsonWriter writer, object value, JsonSerializer serializer)
{
throw new NotImplementedException();
}
}
Then, just annotate your ItemsPayload class with a [JsonConverter] attribute like this and it should work with no other changes to your code:
[JsonConverter(typeof(ItemsPayloadConverter))]
public class ItemsPayload
{
public List<Dictionary<string, string>> Wrapper { get; set; }
}
Fiddle: https://dotnetfiddle.net/9q4tgW
I have the following json:
{
"issue" :
{
"id": 1,
"project":
{
"id":1,
"name":"name of project"
}
}
}
I'm trying to deserialize this json to the follwing class:
public class Issue
{
public int? id { get; set; }
public int project_id { get; set; }
public string project_name { get; set; }
}
Theres a way to get the child attribute and set to the father?
One of the simplest solution is to convert to JObject and using that creates the the required object from it.
var jObject = JsonConvert.DeserializeObject<JObject>(text);
var issue = new Issue() {id = (int?)jObject["issue"]["id"], project_id = (int)jObject["issue"]["project"]["id"], project_name = (string)jObject["issue"]["project"]["name"]};
Below code does the mentioned:
using System;
using System.Linq;
using Newtonsoft.Json;
using Newtonsoft.Json.Linq;
public class Issue
{
public int? id { get; set; }
public int project_id { get; set; }
public string project_name { get; set; }
public override string ToString()
{
return "Id: " + id + " project Id: " + project_id + " project name : " + project_name;
}
}
public class Program
{
public static void Main()
{
var text = "{ \"issue\" : { \"id\": 1, \"project\": { \"id\": 2, \"name\":\"name of project\" }}}";
var jObject = JsonConvert.DeserializeObject<JObject>(text);
var issue = new Issue() {id = (int?)jObject["issue"]["id"], project_id = (int)jObject["issue"]["project"]["id"], project_name = (string)jObject["issue"]["project"]["name"]};
Console.WriteLine(issue);
}
}
You can check the Live demo here.
You need to create new Class for project :
Issue Class :
public class Issue
{
public int id { get; set; }
public Project project { get; set; }
}
Project Class :
public class Project
{
public int id { get; set; }
public String name { get; set; }
}
If you really need to have project_id and project_name in your Issue Class, you can do this :
public class Issue
{
public int id { get; set; }
public Project project { get; set; }
public int getProjectId() {
return this.getProject.getId;
}
//Do the same for projectName
}
Hope this help.
Here is a way to do that
And here is the code
public class ConventionBasedConverter : JsonConverter
{
public override bool CanConvert(Type objectType)
{
return typeof(YOUR-OBJECT).IsAssignableFrom(objectType);
}
public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer)
{
var daat = JObject.Load(reader);
var yourObject = new YOUR-OBJECT();
foreach (var prop in yourObject GetType().GetProperties(BindingFlags.Public | BindingFlags.DeclaredOnly | BindingFlags.Instance))
{
var attr = prop.GetCustomAttributes(false).FirstOrDefault();
if (attr != null)
{
var propName = ((JsonPropertyAttribute)attr).PropertyName;
if (!string.IsNullOrWhiteSpace(propName))
{
//split by the delimiter, and traverse recursevly according to the path
var conventions = propName.Split('/');
object propValue = null;
JToken token = null;
for (var i = 0; i < conventions.Length; i++)
{
if (token == null)
{
token = daat[conventions[i]];
}
else {
token = token[conventions[i]];
}
if (token == null)
{
//silent fail: exit the loop if the specified path was not found
break;
}
else
{
//store the current value
if (token is JValue)
{
propValue = ((JValue)token).Value;
}
}
}
if (propValue != null)
{
//workaround for numeric values being automatically created as Int64 (long) objects.
if (propValue is long && prop.PropertyType == typeof(Int32))
{
prop.SetValue(yourObject, Convert.ToInt32(propValue));
}
else
{
prop.SetValue(yourObject, propValue);
}
}
}
}
}
return yourObject;
}
public override void WriteJson(JsonWriter writer, object value, JsonSerializer serializer)
{
}
}
Then use it like:
var settings = new JsonSerializerSettings();
settings.Converters.Add(new ConventionBasedConverter());
JsonConvert.DeserializeObject<YOUR-OBJECT>(jsonString, settings);
Here is another way to do it. With Cinchoo ETL - an open source library along with JSON path, you can do the deserialization with few lines of code
public class Issue
{
[ChoJSONRecordField(JSONPath = "$..id")]
public int? id { get; set; }
[ChoJSONRecordField(JSONPath = "$..project.id")]
public int project_id { get; set; }
[ChoJSONRecordField(JSONPath = "$..project.name")]
public string project_name { get; set; }
}
static void Sample33()
{
string json = #"{
""issue"" :
{
""id"": 1,
""project"":
{
""id"":1,
""name"":""name of project""
}
}
}";
var issue = ChoJSONReader<Issue>.LoadText(json).First();
}
Disclaimer: I'm the author of this library.
I am trying to serialize model graph using newtonsoft.json, and I know that using ignore attribute or using custom ContractResolver I can ignore specific properties from being serialized?
Here's the custom ContractResolver I am using to ignore properties:
public class PropertyIgnoreSerializerContractResolver : DefaultContractResolver
{
private readonly Dictionary<Type, HashSet<string>> _ignores;
public PropertyIgnoreSerializerContractResolver()
{
_ignores = new Dictionary<Type, HashSet<string>>();
}
public void IgnoreProperty(Type type, params string[] jsonPropertyNames)
{
if (!_ignores.ContainsKey(type))
_ignores[type] = new HashSet<string>();
foreach (var prop in jsonPropertyNames)
_ignores[type].Add(prop);
}
protected override JsonProperty CreateProperty(MemberInfo member, MemberSerialization memberSerialization)
{
var property = base.CreateProperty(member, memberSerialization);
if (IsIgnored(property.DeclaringType, property.PropertyName))
property.ShouldSerialize = i => false;
return property;
}
private bool IsIgnored(Type type, string jsonPropertyName)
{
if (!_ignores.ContainsKey(type))
return false;
return _ignores[type].Contains(jsonPropertyName);
}
}
But in my case I need to include specific properties inside the graph model to be serialized rather than exclude a lot of properties inside that graph?
Is there any way to configure it to serialize specific properties?
I have modified PropertyIgnoreSerializerContractResolver a little bit to reverse the logic to include properties rather than ignoring them.
First of all imagine we have these classes:
public class Student
{
public int Id { get; set; }
public string Name { get; set; }
public List<Course> Courses { get; set; }
}
public class Course
{
public int Id { get; set; }
public string Name { get; set; }
public Person Teacher { get; set; }
}
public class Person
{
public int Id { get; set; }
public string Name { get; set; }
public DateTime? BOD { get; set; }
public decimal Salary { get; set; }
}
Serializing class and my custom ContractResolver to include properties to be serialized they look like this:
public static class SerilizationExtensions
{
public static IContractResolver contractResolver { get; set; }
public static string ToJson(this object obj, IContractResolver contractResolver=null)
{
return JsonConvert.SerializeObject(obj, new JsonSerializerSettings()
{
PreserveReferencesHandling = PreserveReferencesHandling.All,
ContractResolver =contractResolver==null? new PropertyIgnoreSerializerContractResolver():contractResolver
});
}
}
public class PropertyIncludeSerializerContractResolver : DefaultContractResolver
{
private readonly Dictionary<Type, HashSet<string>> _includedProperties;
public PropertyIncludeSerializerContractResolver()
{
_includedProperties = new Dictionary<Type, HashSet<string>>();
}
public void IncludeProperty(Type type, params string[] jsonPropertyNames)
{
if (!_includedProperties.ContainsKey(type))
_includedProperties[type] = new HashSet<string>();
foreach (var prop in jsonPropertyNames)
_includedProperties[type].Add(prop);
}
protected override JsonProperty CreateProperty(MemberInfo member, MemberSerialization memberSerialization)
{
var property = base.CreateProperty(member, memberSerialization);
if (IsIncluded(property.DeclaringType, property.PropertyName) || property.PropertyType.IsValueType || property.PropertyType==typeof(string))
property.ShouldSerialize = i => true;
else
property.ShouldSerialize = i => false;
return property;
}
private bool IsIncluded(Type type, string jsonPropertyName)
{
if (!_includedProperties.ContainsKey(type))
return false;
return _includedProperties[type].Contains(jsonPropertyName);
}
}
Inside Main method :
static void Main(string[] args)
{
var student = new Student
{
Id=1,
Name="Simple Code",
Courses=new List<Course> {
new Course{ Id=1, Name="history", Teacher=new Person{Id=1,Name="James",BOD=DateTime.UtcNow,Salary=1000.50M } },
new Course{ Id=2, Name="Math", Teacher=new Person{Id=2,Name="David",BOD=DateTime.UtcNow,Salary=6000.50M } }
}
};
var jsonResolver = new PropertyIncludeSerializerContractResolver();
jsonResolver.IncludeProperty(typeof(Student), "Courses");
// if you want Teacher property to get serialized uncomment this code
//jsonResolver.IncludeProperty(typeof(Course), "Teacher");
var jsonStr = student.ToJson(jsonResolver);
Console.WriteLine(jsonStr);
Console.ReadLine();
}
So here PropertyIncludeSerializerContractResolver will ignore all reference types which are not specified to be serialized.
I hope my code will help others.
I have a Web Api Controller like this one :
public IHttpActionResult Create(PaymentDTO Payment)
My DTOs are:
public class PaymentDTO
{
public int Id { get; set; }
public string type { get; set; }
public IEnumerable<TransactionDTO> Transactions { get; set; }
}
public class TransactionDTO
{
public int Id { get; set; }
public string Description { get; set; }
public string CreateTime { get; set; }
public string UpdateTime { get; set; }
}
public class SaleDTO : TransactionDTO
{
public string Total { get; set; }
public string Currency{ get; set; }
}
public class OrderDTO : TransactionDTO
{
public string State {get;set;}
}
I receive the following JSON formatted data :
{
"Type": "sale",
"Id": 101,
"transactions": [
{
"Total": "30.50",
"Currency": "USD",
"Description": "transaction description"
}
]
}
I want JSON.net to instantiate either a IEnumerable<SaleDTO> or IEnumerable<OrderDTO> based on the Type Property.
I could've used a custom type converter, but only if Type property was in TransactionDTO. But I want the Type property to be in the parent object (PaymentDTO)
Thank you in advance for your help.
You can do this with a custom JsonConverter on the PaymentDTO class:
public class PaymentDTOConverter : JsonConverter
{
public override bool CanConvert(Type objectType)
{
return typeof(PaymentDTO).IsAssignableFrom(objectType);
}
public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer)
{
if (reader.TokenType == JsonToken.Null)
return null;
var obj = JObject.Load(reader);
var payment = (PaymentDTO)existingValue ?? new PaymentDTO();
// Extract the transactions.
var transactions = obj.Property("transactions") ?? obj.Property("Transactions");
if (transactions != null)
transactions.Remove();
// Populate the remaining regular properties.
using (var subReader = obj.CreateReader())
serializer.Populate(subReader, payment);
if (transactions != null)
{
// Deserialize the transactions list.
var type = PaymentDTO.GetTransactionDTOType(payment.type) ?? typeof(TransactionDTO);
using (var subReader = transactions.Value.CreateReader())
// Here we are taking advantage of array covariance.
payment.Transactions = (IEnumerable<TransactionDTO>)serializer.Deserialize(subReader, type.MakeArrayType());
}
return payment;
}
public override bool CanWrite { get { return false; } }
public override void WriteJson(JsonWriter writer, object value, JsonSerializer serializer)
{
throw new NotImplementedException();
}
}
Then apply it to your PaymentDTO class as follows:
[JsonConverter(typeof(PaymentDTOConverter))]
public class PaymentDTO
{
static Dictionary<string, Type> namesToTransactions;
static Dictionary<Type, string> transactionsToNames = new Dictionary<Type, string>
{
{ typeof(SaleDTO), "sale" },
{ typeof(OrderDTO), "order" },
};
static PaymentDTO()
{
namesToTransactions = transactionsToNames.ToDictionary(p => p.Value, p => p.Key);
}
public static string GetTransactionDTOTypeName<TTransactionDTO>() where TTransactionDTO : TransactionDTO
{
string name;
if (transactionsToNames.TryGetValue(typeof(TTransactionDTO), out name))
return name;
return null;
}
public static Type GetTransactionDTOType(string name)
{
Type type;
if (namesToTransactions.TryGetValue(name, out type))
return type;
return null;
}
public int Id { get; set; }
public string type { get; set; }
[JsonProperty("transactions")]
public IEnumerable<TransactionDTO> Transactions { get; set; }
}