I am serializing an object of this format using Newtonsoft.JSON:
class Message
{
public HeaderType Header { get; set; }
public object Body { get; set; }
}
I want to turn the Header and Body properties into camel case, while presevering the case of the properties of the thing assigned to Body.
So if the message looks like:
var result = new Message() { Header = myHeader, Body = new SomeClass() { A = 1 }});
I want the output to look like:
{ header = myHeader, body = { A = 1 } } // I realize this isn't valid C#
Right now, I'm doing this to get the camel case conversion, but of course it's affecting everything.
string stringRepresentationOfObj = JsonConvert.SerializeObject(obj, new JsonSerializerSettings {
ContractResolver = new DefaultContractResolver {
NamingStrategy = new CamelCaseNamingStrategy()
}
});
Is there a way to ignore certain parts of the object? I see that the docs call out OverrideSpecifiedNames, ProcessDictionaryKeys, and ProcessExtensionDataNames, but it doesn't look like that's what I want.
Am I forced to use a some kind of custom naming strategy? How can I achieve this?
You can configure a CamelCaseNamingStrategy to not camel case properties that already have a name specified with an attribute, Check documentation here
Specify property name as below
[JsonProperty(PropertyName = "Name")]
public string Name{ get; set; }
And in CamelCaseNamingStrategy set OverrideSpecifiedNames = false
string stringRepresentationOfObj = JsonConvert.SerializeObject(obj, new JsonSerializerSettings
{
ContractResolver = new DefaultContractResolver
{
NamingStrategy = new CamelCaseNamingStrategy()
{
OverrideSpecifiedNames = false
}
}
});
Another way is to modify your type only using JsonObject attribute as below,
this will force your type properties only to be in camelCase and any nested properties will not be affected.
[JsonObject(NamingStrategyType = typeof(CamelCaseNamingStrategy))]
public class ApiMessage
{
public HeaderType Header { get; set; }
public object Body { get; set; }
}
Also, add JsonObject attribute to HeaderType class
[JsonObject(NamingStrategyType = typeof(CamelCaseNamingStrategy))]
public class HeaderType
{
public string MyPropertyA { get; set; }
public string MyPropertyB { get; set; }
}
Your result should be as below
{
"header": {
"myPropertyA": "AAA",
"myPropertyB": "BBB"
},
"body": {
"ObjectPropertyA": "Value A",
"ObjectPropertyB": "Value B",
"ObjectPropertyC": "Value C"
}
}
You can create your own resolver to behave this way.
You'd create one, possibly have it look for a new attribute (which you'd create), that you can then use to decorate the properties you don't want camelCased.
Related
I'm probably missing something.
I'd like to test behavior when an API call response returns a property of null and I would like to throw an exception when that happens.
I have a Form object as follow
public class Form
{
[Required]
public string Html { get; set; }
public string Json { get; set; }
public string Name { get; set; }
}
I have initialized an object
var myData = new
{
Json = "foo",
};
string jsonData = JsonConvert.SerializeObject(myData);
var response = JsonConvert.DeserializeObject<Form>(File.ReadAllText(jsonPath));
I was expecting to have an exception since the Html property is required and not nullable,
but actually getting the object as
{
Html = null,
Json = foo,
Name = null
}
I have tried to use JsonSerializerSettings as follows but this actually throws an exception only when there is an additional unwanted property and not when there's a missing one.
JsonSerializerSettings config = new JsonSerializerSettings { MissingMemberHandling = MissingMemberHandling.Error, NullValueHandling = NullValueHandling.Include};
var res = JsonConvert.DeserializeObject<Form>(json,config);
You need [JsonProperty(Required = Required.Always)].
public class Form
{
[JsonProperty(Required = Required.Always)]
public string Html { get; set; }
public string Json { get; set; }
public string Name { get; set; }
}
Sample Program
While [Required] attribute is for Data Annotation.
Reference
JsonPropertyAttribute required
I want to camel case specific properties of an object using Json.NET rather than all of the properties.
I have an object like this:
class A {
public object B { get; set; }
public object C { get; set; } // this property should be camel cased
}
I want it to get serialized to this:
{ B: 1, c: 2 }
I came across this post about camel casing all properties unconditionally, which is done using:
var settings = new JsonSerializerSettings
{
ContractResolver = new CamelCasePropertyNamesContractResolver()
};
var json = JsonConvert.SerializeObject(a, settings);
But I couldn't find a counter-part question for camel casing a specific property. How is this done?
You can apply JsonPropertyAttribute's NamingStrategyType to the field that you want to camel case:
class A
{
[JsonProperty(NamingStrategyType = typeof(CamelCaseNamingStrategy))]
public object C { get; set; }
}
Or you can specify the name of the Property directly:
class A
{
[JsonProperty("c")]
public object C { get; set; }
}
This question already has answers here:
Use different name for serializing and deserializing with Json.Net
(3 answers)
Closed 5 years ago.
I am trying to read a JSON file, rename the property names, and export a new JSON with the new names. As stated in this example, https://www.newtonsoft.com/json/help/html/JsonPropertyName.htm, we can use JsonProperty to specify a different name internally in the code. However, when you export the json, it returns the original name. So in the example it still returned "release_date" instead of "ReleaseDate" when it was logged in the console. Is there any way to do this without creating a brand new object?
To clear things up, here is example of what I am trying to do:
JSON Input:
{ "name": "Starcraft", "release_date": "1998-01-01T00:00:00" }
Object Used to deserialize the data:
public class Videogame
{
public string name{ get; set; }
[JsonProperty("release_date")]
public DateTime releaseDate { get; set; }
}
Code that is called:
var json = JsonConvert.DeserializeObject<Videogame>(File.ReadAllText(path))
Console.WriteLine(JsonConvert.SerializeObject(json));
Resulted Output:
{ "name": "Starcraft", "release_date": "1998-01-01T00:00:00" }
Desired Output:
{ "name": "Starcraft", "releaseDate": "1998-01-01T00:00:00" }
The only way that I currently know how to solve it is to create a new object and use it to serialize my output. Wasn't sure if there is any simpler way to do this.
The following will work:
public class Videogame
{
public string name{ get; set; }
[JsonProperty("release_date")]
public DateTime old
{
set { ReleaseDate = value; }
}
[JsonProperty("releaseDate")]
public DateTime ReleaseDate { get; set; }
}
When deserializing, the old property will redirect its value to the new property.
Since the old property is a setter only, it will not be serialized back.
I would not consider this approach for large amounts of renaming. It's then better to follow the advices given in the comments.
You could use custom resolve to create desired behaviour:
public class CustomContractResolver : DefaultContractResolver
{
public bool UseJsonPropertyName { get; }
public CustomContractResolver(bool useJsonPropertyName)
{
UseJsonPropertyName = useJsonPropertyName;
}
protected override JsonProperty CreateProperty(MemberInfo member, MemberSerialization memberSerialization)
{
var property = base.CreateProperty(member, memberSerialization);
if (!UseJsonPropertyName)
property.PropertyName = property.UnderlyingName;
return property;
}
}
public class ErrorDetails
{
public int Id { get; set; }
[JsonProperty("error_message")]
public string ErrorMessage { get; set; }
}
var json = "{'Id': 1,'error_message': 'An error has occurred!'}";
var serializerSettings = new JsonSerializerSettings()
{
ContractResolver = new CustomContractResolver(false)
};
var dezerializerSettings = new JsonSerializerSettings
{
ContractResolver = new CustomContractResolver(true)
};
var obj = JsonConvert.DeserializeObject<ErrorDetails>(json, dezerializerSettings);
var jsonNew = JsonConvert.SerializeObject(obj, serializerSettings);
Kudos to NtFreX and his answer. I'm providing mine so that you can indicate that your question is resolved.
I am receiving JSON data from a web API that looks like this:
[
{
"id": 1
"error_message": "An error has occurred!"
}
]
I deserialize this data to objects of the following type:
public class ErrorDetails
{
public int Id { get; set; }
[JsonProperty("error_message")]
public string ErrorMessage { get; set; }
}
Later in my application I would like to serialize the ErrorDetails object again to JSON but using the property name ErrorMessage instead of error_message. So the result would look like this:
[
{
"Id": 1
"ErrorMessage": "An error has occurred!"
}
]
Is there an easy way I can accomplish this with Json.Net? Perhaps using a custom resolver and some attributes like:
public class ErrorDetails
{
public int Id { get; set; }
[SerializeAs("ErrorMessage")]
[DeserializeAs("error_message")]
public string ErrorMessage { get; set; }
}
But the resolver doesn't tell me when I'm serializing or deserializing.
You can make use of the JsonSerializerSettings, the ContractResolver and the NamingStrategy.
public class ErrorDetails
{
public int Id { get; set; }
public string ErrorMessage { get; set; }
}
var json = "{'Id': 1,'error_message': 'An error has occurred!'}";
For dezerialization you could use the SnakeCaseNamingStrategy.
var dezerializerSettings = new JsonSerializerSettings
{
ContractResolver = new DefaultContractResolver
{
NamingStrategy = new SnakeCaseNamingStrategy()
}
};
var obj = JsonConvert.DeserializeObject<ErrorDetails>(json, dezerializerSettings);
To serialize the object again you dont have to change the JsonSerializerSettings as the default will use the property name.
var jsonNew = JsonConvert.SerializeObject(obj);
jsonNew = "{'Id': 1,'ErrorMessage': 'An error has occurred!'}"
Or you could create a contract resolver which can decide which name to use. Then you can decide when you dezerialize and serialize if you want to use the pascal case name format or the one with the underscore.
public class CustomContractResolver : DefaultContractResolver
{
public bool UseJsonPropertyName { get; }
public CustomContractResolver(bool useJsonPropertyName)
{
UseJsonPropertyName = useJsonPropertyName;
}
protected override JsonProperty CreateProperty(MemberInfo member, MemberSerialization memberSerialization)
{
var property = base.CreateProperty(member, memberSerialization);
if (!UseJsonPropertyName)
property.PropertyName = property.UnderlyingName;
return property;
}
}
public class ErrorDetails
{
public int Id { get; set; }
[JsonProperty("error_message")]
public string ErrorMessage { get; set; }
}
var json = "{'Id': 1,'error_message': 'An error has occurred!'}";
var serializerSettings = new JsonSerializerSettings()
{
ContractResolver = new CustomContractResolver(false)
};
var dezerializerSettings = new JsonSerializerSettings
{
ContractResolver = new CustomContractResolver(true)
};
var obj = JsonConvert.DeserializeObject<ErrorDetails>(json, dezerializerSettings);
var jsonNew = JsonConvert.SerializeObject(obj, serializerSettings);
jsonNew = "{'Id': 1,'ErrorMessage': 'An error has occurred!'}"
Another way of achieving a different property name when serialising vs deserisalising is by using the ShouldSerialize method: https://www.newtonsoft.com/json/help/html/ConditionalProperties.htm#ShouldSerialize
The docs say:
To conditionally serialize a property, add a method that returns
boolean with the same name as the property and then prefix the method
name with ShouldSerialize. The result of the method determines whether
the property is serialized. If the method returns true then the
property will be serialized, if it returns false then the property
will be skipped.
E.g:
public class ErrorDetails
{
public int Id { get; set; }
// This will deserialise the `error_message` property from the incoming json into the `GetErrorMessage` property
[JsonProperty("error_message")]
public string GetErrorMessage { get; set; }
// If this method returns false then the property after the `ShouldSerialize` prefix will not be serialised into the output
public bool ShouldSerializeGetErrorMessage() => false;
// The serialised output will return `ErrorMessage` with the value from `GetErrorMessage` i.e. `error_message` in the original json
public string ErrorMessage { get { return GetErrorMessage; } }
}
This results in slightly more overhead so be careful if dealing with lots of properties or with lots of data but for small payloads, and if you don't mind messing up your DTO class a little, then this could be a quicker solution than writing custom contract resolvers etc.
I liked the answer by #lee_mcmullen, and implemented it in my own code. Now I think I've found a slightly neater version.
public class ErrorDetails
{
public int Id { get; set; }
// This will deserialise the `error_message` property from the incoming json and store it in the new `GetErrorMessage` property
[JsonProperty("error_message")]
public string GetErrorMessage { get { return ErrorMessage; } set { ErrorMessage = value; } }
// If this method returns false then the property after the `ShouldSerialize` prefix will not be serialised into the output
public bool ShouldSerializeGetErrorMessage() => false;
// The serialised output will return `ErrorMessage` with the value set from `GetErrorMessage` i.e. `error_message` in the original json
public string ErrorMessage { get; set; }
}
The reason I like this better is that in more complicated models it allows for inheritance while keeping all of the "old" custom stuff separate
public class ErrorDetails
{
public int Id { get; set; }
public string ErrorMessage { get; set; }
}
// This is our old ErrorDetails that hopefully we can delete one day
public class OldErrorDetails : ErrorDetails
{
// This will deserialise the `error_message` property from the incoming json and store it in the new `GetErrorMessage` property
[JsonProperty("error_message")]
public string GetErrorMessage { get { return ErrorMessage; } set { ErrorMessage = value; } }
// If this method returns false then the property after the `ShouldSerialize` prefix will not be serialised into the output
public bool ShouldSerializeGetErrorMessage() => false;
}
I'm communicating with a JSON-based API which I can't change. It always returns a Response object with a varying Result object inside. Typically it looks like this:
{ "ver": "2.0", "result": { "code": 0 } }
For certain commands the Result object is 'grown' by adding extra properties:
{ "ver": "2.0", "result": { "code": 0, "hostName": "sample", "hostPort": 5000 } }
I've used Newtonsoft attributes to define the objects as follows:
internal class RpcResponse
{
[JsonProperty(PropertyName = "ver")]
public string Version { get; set; }
[JsonProperty(PropertyName = "result")]
public RpcResponseResult Result
{
get;
set;
}
internal class RpcResponseResult
{
[JsonProperty(PropertyName = "code")]
public int Code { get; set; }
}
internal class RpcExtendedResponseResult: RpcResponseResult
{
[JsonProperty(PropertyName = "hostName")]
public string HostName { get; set; }
[JsonProperty(PropertyName = "hostPort")]
public int HostPort { get; set; }
But when the Response object is deserialized:
RpcResponse rspResponse = JsonConvert.DeserializeObject<RpcResponse>(rspString);
Its Result property always appears as an RpcResponseResult object, ie. JsonConvert doesn't know to construct it as a RpcExtendedResponseResult object.
Is there some way with Attributes or Converters to reinstate the correct descendent object? I feel like I'm missing something obvious!
It's because the type of the object is RpcResponseResult. The deserializer can only deserialize fields that are declared in the type of the field specified. It can't determine because a class has "hostName" its now an RpcExtendedResponseResult.
If I were doing this, I might make the result a container for all possible fields with default values if needed, and then you can fill another object as needed.
internal class RpcResponseResultContainer
{
[JsonProperty(PropertyName = "code")]
public int Code { get; set; }
[JsonProperty(PropertyName = "hostName")]
private string mHostName = string.Empty;
public string HostName
{
get { return mHostName;}
set { mHostName = value; }
}
[JsonProperty(PropertyName = "hostPort")]
private int mHostPort = -1;
public int HostPort
{
get { return mHostPort;}
set { mHostPort = value;}
}
Then if you really wanted to get your object as you want it, you could do something like this in your container class:
public RpcResponseResult GetActualResponseType()
{
if(HostPort != -1 && !string.IsNullOrEmtpy(HostName))
{
return new RpcExtendedResponseResult() { Code = this.Code, HostName = this.HostName, HostPort = this.HostPort};
}
return new RpcResponseResult() { Code = this.Code };
}
First, credit to Matthew Frontino for providing the only answer which I've accepted.
However I opted not to make a single result container, so here's what I ended up doing.
First I started with this page: How to implement custom JsonConverter in JSON.NET to deserialize a List of base class objects?
I used the version of JsonCreationConverter provided there by Alain.
I added the CanWrite override as suggested there by Dribbel:
public override bool CanWrite
{
get { return false; }
}
I also added my own helper function to JsonCreationConverter:
protected bool FieldExists(string fieldName, JObject jObject) {
return jObject[fieldName] != null;
}
Then I created my own converter as follows:
class RpcResponseResultConverter : JsonCreationConverter<RpcResponseResult>
{
protected override RpcResponseResult Create(Type objectType, JObject jObject)
{
// determine extended responses
if (FieldExists("hostName", jObject) &&
FieldExists("hostPort", jObject) )
{
return new RpcExtendedResponseResult();
}
//default
return new RpcResponseResult();
}
}
Then I deserialize the top-level class and supply any converters to be used. In this case I only supplied one, which was for the nested class in question:
RpcResponse rspResponse = JsonConvert.DeserializeObject<RpcResponse>(
rspString,
new JsonSerializerSettings {
DateParseHandling = Newtonsoft.Json.DateParseHandling.None,
Converters = new List<JsonConverter>( new JsonConverter[] {
new RpcResponseResultConverter()
})
});
Notes:
Anything not explicitly handled by a converter (such as the top-level class) is deserialized using the default converter built into JsonConvert.
This only works if you can identify a unique set of fields for every descendent class.