Avoid auto lowercase first letter in asp.net json response - asp.net

In my asp.net razor project, json response always lowercase the first letter, which is annoying. Since I would then deal with different names from backend to frontend.
My Class:
[JsonProperty("Test")]
public string Test { get; set; } => json responce: Test (good)
public string Test2 { get; set; } => json responce: test2 (bad)
[JsonPropertyName("Test3")]
public string Test3 { get; set; } => json responce: test3 (bad)
Can I avoid adding a JsonProperty markup on every value field?

You can create your custom formatter or use DefaultContractResolver by giving NamingStrategy. For e.g. check below code:
User user = new User
{
UserName = "jamesn",
Enabled = true
};
DefaultContractResolver contractResolver = new DefaultContractResolver
{
NamingStrategy = new CamelCaseNamingStrategy()
};
string json = JsonConvert.SerializeObject(user1, new JsonSerializerSettings
{
ContractResolver = contractResolver,
Formatting = Formatting.Indented
});
Console.WriteLine(json);

Related

Json Deserialization in an ASP.NET not working properly

I have an API that returns the following response as string
[
{
"id": "62a9f8f90346133662624bd3",
"referenceID": "test1",
"additionalInfoList": ["string"]
},
{
"id": "62a9fba50346133662624bd4",
"referenceID": "111",
"additionalInfoList": ["string"]
}
]
edit: where the exact formatting of the string is as follows with escaping backslashes:
"[{\"id\":\"62a9f8f90346133662624bd3\",\"referenceID\":\"test1\",\"additionalInfoList\":[\"string\"]},{\"id\":\"62a9fba50346133662624bd4\",\"referenceID\":\"111\",\"additionalInfoList\":[\"string\"]}]"
and the following class model
public class IncidentModel
{
public string id { get; set; }
public string referenceID { get; set; }
public List<string> AdditionalInfoList { get; set; }
}
The problem arises in the code to deserialize. While I get a list with 2 elements, there is no data, only some generic metadata and fields that are not part of the model.
public async Task<JsonResult> OnGetIncidentsAsync()
{
List<IncidentModel> incidents = new List<IncidentModel>();
using (var httpClient = new HttpClient())
{
using (HttpResponseMessage response = await httpClient.GetAsync("api/Incident/GetAllIncidents.json/"))
{
string apiResponse = await response.Content.ReadAsStringAsync();
incidents = JsonConvert.DeserializeObject<List<IncidentModel>>(apiResponse);
}
}
return new JsonResult(incidents);
}
The attached image shows the data inside incidents.
How can I solve this?
So it turns out in Pages, I had a page named Incident. Because I use Razor pages, this page had a Model, named IncidentModel.cshtml.cs which was overriding the IncidentModel.cs from the Models folder. Renaming the model fixed the problem.

System.Text.Json Deserialize Fails

With this DTO:
public class QuestionDTO {
public Guid Id { get; set; }
public string Prompt { get; set; }
public List<Answer> Choices { get; set; }
public QuestionDTO() {
}
public QuestionDTO(Question question) {
this.Id = question.Id;
this.Prompt = question.Prompt;
this.Choices = question.Choices;
}
}
I was getting an error about Unable to Parse without a parameterless constructor. I have since fixed that, but now my objects are de-serialized empty:
using System.Text.Json;
var results = JsonSerializer.Deserialize<List<QuestionDTO>>(jsonString);
The jsonString contains 3 items with the correct data, and the deserialized list contains 3 items, but all the properties are empty.
The new json library is case sensitive by default. You can change this by providing a settings option. Here is a sample:
private JsonSerializerOptions _options = new JsonSerializerOptions { PropertyNameCaseInsensitive = true }
private async Task SampleRequest()
{
var result = await HttpClient.GetStreamAsync(QueryHelpers.AddQueryString(queryString, queryParams));
_expenses = await JsonSerializer.DeserializeAsync<List<Common.Dtos.Expenses.Models.Querys.ExpensesItem>>(result, _options);
}

Parse JObject into a mixed object (static + dynamic fields)

given the following json
{
"$$href": "http://localhost:8080/url1",
"name": "Sebastian Slutzky"
}
I'd like to deserialize it into an object like this one
public class DomainObject
{
[JsonProperty("$$href")]
public string href { get; set; }
public JObject this[string key] => throw new NotImplementedException();
}
so that arbitrary properties (like name can be accessed dynamically)
var href = domainObject.href;
var name = domainObject["name"] as string;
My current implementation is by passing the JObject to the constructor of my object, and decorate it (i.e. composition). Is there a way of solving this by inheritance instead (i.e. by extending JObject?
Any other solution?
You could make use of JsonExtensionData. For example
public class DomainObject
{
[JsonProperty("$$href")]
public string href { get; set; }
[JsonExtensionData]
private IDictionary<string, JToken> UnknownTypes;
public JToken this[string key] => UnknownTypes[key];
}
The Indexer now allows you to retrieve the values of dynamic properties with key as the following.
var result = JsonConvert.DeserializeObject<DomainObject>(json);
var name = result["name"].Value<string>();

Data Annotations to sanitize request and response before logging

I'm looking for a reliable solution to log details of requests and responses made to and from our controllers. However, some of the data passing through contains sensitive information that should not be written to a log.
In the controller, the inbound request is bound to a single model from the request body, and as the request is answered, a single model is passed to the Ok() result like this (very simplified):
[HttpGet]
[Route("Some/Route")]
public IHttpActionResult SomeController([FromBody] RequestType requestObj)
{
ResponseType responseObj = GetResponse(requestObj)
return this.Ok(responseObj);
}
Now my goal is to somehow log the contents of the request and response object at the beginning and end of the controller, respectively. What I would like to do is bind the models first, then log out their attributes. An example of the RequestType is something like:
public class RequestType
{
public string SomeAttribute { get; set; }
public string AnotherAttribute { get; set; }
public string Password{ get; set; }
}
And the log would look something like:
[date-time] Request to SomeController:
SomeAttribute: "value_from_request"
AnotherAttribute: "another_value"
Password: "supersecret123"
Now clearly we don't want the password to be logged. So I would like to create a custom data annotation that would not log certain fields. Its use would look like this (updated RequestType):
public class RequestType
{
public string SomeAttribute { get; set; }
public string AnotherAttribute { get; set; }
[SensitiveData]
public string Password{ get; set; }
}
Where would I start with this? I'm not incredibly familliar with .NET, but know that there are many sort of magic classes that can be subclassed to override some of their functionality. Is there any such class that can help here? Even better, is there any way to do this during the model binding? So we could catch errors that occur during model binding as well?
We should be able to achieve what you're looking for with an ActionFilterAttribute.
Capture Requests Attribute
[AttributeUsage(AttributeTargets.Class | AttributeTargets.Method, AllowMultiple = false, Inherited = false)]
public sealed class CaptureRequestsAttribute : ActionFilterAttribute // *IMPORTANT* This is in the System.Web.Http.Filters namespace, not System.Web.Mvc
{
public override void OnActionExecuting(HttpActionContext actionContext)
{
var messages = actionContext.ActionArguments.Select(arg => GetLogMessage(arg.Value));
var logMessage = $"[{DateTime.Now}] Request to " +
$"{actionContext.ControllerContext.Controller}]:\n{string.Join("\n", messages)}";
WriteToLog(logMessage);
base.OnActionExecuting(actionContext);
}
public override void OnActionExecuted(HttpActionExecutedContext actionExecutedContext)
{
var result = actionExecutedContext.Response.Content as ObjectContent;
var message = GetLogMessage(result?.Value);
var logMessage = $"[{DateTime.Now}] Response from " +
$"{actionExecutedContext.ActionContext.ControllerContext.Controller}:\n{message}";
WriteToLog(logMessage);
base.OnActionExecuted(actionExecutedContext);
}
private static void WriteToLog(string message)
{
// todo: write you logging stuff here
}
private static string GetLogMessage(object objectToLog)
{
if (objectToLog == null)
{
return string.Empty;
}
var type = objectToLog.GetType();
var properties = type.GetProperties();
if (properties.Length == 0)
{
return $"{type}: {objectToLog}";
}
else
{
var nonSensitiveProperties = type
.GetProperties()
.Where(IsNotSensitiveData)
.Select(property => $"{property.Name}: {property.GetValue(objectToLog)}");
return string.Join("\n", nonSensitiveProperties);
}
}
private static bool IsNotSensitiveData(PropertyInfo property) =>
property.GetCustomAttributes<SensitiveDataAttribute>().Count() == 0;
}
Sensitive Data Attribute
[AttributeUsage(AttributeTargets.Property, AllowMultiple = false, Inherited = true)]
public sealed class SensitiveDataAttribute : Attribute
{
}
Then, you can just add it to your WebApi controller (or a specific method in it):
[CaptureRequests]
public class ValuesController : ApiController
{
// .. methods
}
And finally your models can just add the SensitiveDataAttribute:
public class TestModel
{
public string Username { get; set; }
[SensitiveData]
public string Password { get; set; }
}
This does not make use of DataAnnotations,however, One way that comes to mind would be to use the serialization. If your payload is within a reasonable size you could serialize and deserialize your RequestType class when reading and writing to/from a log. This would require a custom serialization format or making use of the default, xml.
[Seriliazeble()]
public class RequestType
{
public string SomeAttribute { get; set; }
public string AnotherAttribute { get; set; }
[NonSerialized()]
public string Password{ get; set; }
}
Using the above attribute will omit Password from serialization. Then you copuld proceed to Logger.Log(MySerializer.Serialize(MyRequest)); and your sensitive data will be omitted.
This link describes the approach in detail.
For xml serialization, simply use the XmlSerializer class.
public class MySerializationService
{
public string SerializeObject(object item)
{
XmlSerializer serializer = new XmlSerializer(item.GetType());
System.IO.MemoryStream aMemStr = new System.IO.MemoryStream();
System.Xml.XmlTextWriter writer = new System.Xml.XmlTextWriter(aMemStr, null);
serializer.Serialize(writer, item);
string strXml = System.Text.Encoding.UTF8.GetString(aMemStr.ToArray());
return strXml;
}
public object DeSerializeObject(Type objectType, string objectString)
{
object obj = null;
XmlSerializer xs = new XmlSerializer(objectType);
obj = xs.Deserialize(new StringReader(objectString));
return obj;
}
}
Then using the above or similar methods you can read and write in a custom format.
Write :
string logData=new MySerializationService().SerializeObject(myRequest);
Read :
RequestType loggedRequest= (RequestType)new MySerializationService().DeSerializeObject(new RequestType().GetType(), logData);

Serializing Array of Objects to JSON in WCF to Comply with OpenSearch

I'm trying to write an OpenSearch Suggestion service that complies with the OpenSearch spec.
http://www.opensearch.org/Specifications/OpenSearch/Extensions/Suggestions
This spec requires the service to return a JSON array with the first element being a string and the following elements being arrays of strings. I'm able to get it almost there by returning an array of strings (string[][]) and having WCF serialize this into JSON. However, in order to comply with the spec, I tried to return an array of objects (object[]), with the first one being a string, and the rest being arrays of strings (string[]).
Whenever I try to return the array of objects, it doesn't work, such as this:
From service:
[AspNetCompatibilityRequirements(RequirementsMode = AspNetCompatibilityRequirementsMode.Allowed)]
public class SuggestionService : ISuggestionService
{
public object[] Search(string searchTerms)
{
SearchSuggestions = new object[4];
SearchText = searchTerms;
SearchSuggestions[0] = SearchText;
Text = new string[10];
Urls = new string[10];
Descriptions = new string[10];
// Removed irrelevant ADO.NET code
while (searchResultReader.Read() && index < 10)
{
Text[index] = searchResultReader["Company"].ToString();
Descriptions[index] = searchResultReader["Company"].ToString();
Urls[index] = "http://dev.localhost/Customers/EditCustomer.aspx?id=" +
searchResultReader["idCustomer"];
index++;
}
SearchSuggestions[1] = Text;
SearchSuggestions[2] = Descriptions;
SearchSuggestions[3] = Urls;
return SearchSuggestions;
}
[DataMember]
public string SearchText { get; set; }
[DataMember]
public string[] Text { get; set; }
[DataMember]
public string[] Descriptions { get; set; }
[DataMember]
public string[] Urls { get; set; }
[DataMember]
public object[] SearchSuggestions { get; set; }
}
Here's the entire interface:
[ServiceContract]
public interface ISuggestionService
{
[OperationContract]
[WebGet(UriTemplate = "/Search?q={searchTerms}",
BodyStyle = WebMessageBodyStyle.Bare,
ResponseFormat = WebMessageFormat.Json)]
object[] Search(string searchTerms);
}
This causes the service to return "Error 324 (net::ERR_EMPTY_RESPONSE): Unknown error." This is the only error I've been able to get.
Am I not able to use an array of objects to store one string and three arrays? What else could I do in order to use WCF to return the proper JSON that complies with this spec?
EDIT: Added lots more of the code
You posted a bunch of [DataMember]'s. Please post the entire [DataContract]. Also show us the JSON returned when you return that DataContract.
A Data Contract should never include behavior. Try the following (I haven't had a chance to test it, and will need to fake up the data to do so):
[AspNetCompatibilityRequirements(RequirementsMode = AspNetCompatibilityRequirementsMode.Allowed)]
public class SuggestionService : ISuggestionService
{
public SearchResults Search(string searchTerms)
{
var results = new SearchResults
{
SearchText = searchTerms,
Text = new string[10],
Urls = new string[10],
Descriptions = new string[10]
};
// Removed irrelevant ADO.NET code
int index = 0;
while (searchResultReader.Read() && index < 10)
{
results.Text[index] = searchResultReader["Company"].ToString();
results.Descriptions[index] = searchResultReader["Company"].ToString();
results.Urls[index] = "http://dev.localhost/Customers/EditCustomer.aspx?id=" +
searchResultReader["idCustomer"];
index++;
}
return results;
}
}
[DataContract]
public class SearchResults
{
[DataMember]
public string SearchText { get; set; }
[DataMember]
public string[] Text { get; set; }
[DataMember]
public string[] Descriptions { get; set; }
[DataMember]
public string[] Urls { get; set; }
}
Ok, I read enough of that spec and of the JSON spec, to convince myself you really do need to return an array of objects, and not an instance of a class that contains an array of objects. Of course, that didn't quite work. Here's what you needed:
[ServiceContract]
[ServiceKnownType(typeof(string))]
[ServiceKnownType(typeof(string[]))]
public interface ISuggestionService
{
[OperationContract]
[WebGet(UriTemplate = "/Search?q={searchTerms}",
BodyStyle = WebMessageBodyStyle.Bare,
ResponseFormat = WebMessageFormat.Json)]
object[] Search(string searchTerms);
}
I just tried it, and it worked. Here's the JSON (indentation added):
[
"abc",
["Company1","Company2","Company3",...],
["Company1 Description","Company2 Description","Company3 Description",...],
["http:\/\/dev.localhost\/Customers\/EditCustomer.aspx?id=1",
"http:\/\/dev.localhost\/Customers\/EditCustomer.aspx?id=2",
"http:\/\/dev.localhost\/Customers\/EditCustomer.aspx?id=3",...]
]
This is a problem that had me stumped for a while as well - there's a complete end-to-end walkthrough of how to do this, including how to support both JSON and XML opensearch (including XML attribute serialization), with downloadable code, at "Building Labs – Writing an OpenSearch Suggestions provider in C# with WCF".

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