Failed to serialize the response in Web API with Json

Question

I am working with ASP NET MVC 5 Web Api  I want consult all my users   I wrote api users and I receive this       The  ObjectContent 1  type failed to serialize the response body for content type  application json  charset utf-8     In WebApiConfig  already I added these lines   HttpConfiguration config   new HttpConfiguration    config Formatters XmlFormatter SupportedMediaTypes Remove appXmlType   config Formatters JsonFormatter SerializerSettings ReferenceLoopHandling   Newtonsoft Json ReferenceLoopHandling Ignore     But it still doesn t work   My function for return data is this   public IEnumerable lt User gt  GetAll         using  Database db   new Database                  return db Users ToList

User · Answer

In my case I solved recreating the database. I made some changes in a model and launching Update-Database in Package Manager Console I got the following Error:

"The ALTER TABLE statement conflicted with the FOREIGN KEY constraint "FK_dbo.Activities_dbo.Projects_ProjectId". The conflict occurred in database "TrackEmAllContext-20190530144302", table "dbo.Projects", column 'Id'."

User · Answer

If you are working with EF  besides adding the code below on Global asax  GlobalConfiguration Configuration Formatters JsonFormatter SerializerSettings      ReferenceLoopHandling   Newtonsoft Json ReferenceLoopHandling Ignore  GlobalConfiguration Configuration Formatters      Remove GlobalConfiguration Configuration Formatters XmlFormatter               Dont t forget to import   using System Data Entity    Then you can return your own EF Models  Simple as that

User · Answer

When it comes to returning data back to the consumer from Web Api  or any other web service for that matter   I highly recommend not passing back entities that come from a database   It is much more reliable and maintainable to use Models in which you have control of what the data looks like and not the database   That way you don t have to mess around with the formatters so much in the WebApiConfig   You can just create a UserModel that has child Models as properties and get rid of the reference loops in the return objects   That makes the serializer much happier   Also  it isn t necessary to remove formatters or supported media types typically if you are just specifying the  Accepts  header in the request   Playing around with that stuff can sometimes make things more confusing   Example   public class UserModel       public string Name  get set       public string Age  get set          Other properties here that do not reference another UserModel class

User · Answer

public class UserController   ApiController       Database db   new Database           construction    public UserController                 Add the following code          problem will be solved       db Configuration ProxyCreationEnabled   false           public IEnumerable lt User gt  GetAll                     return db Users ToList

User · Answer

I resolved it using this code to WebApiConfig cs file  var json   config Formatters JsonFormatter  json SerializerSettings PreserveReferencesHandling   Newtonsoft Json PreserveReferencesHandling Objects   config Formatters Remove config Formatters XmlFormatter

User · Answer

In case  If adding code to WebApiConfig cs or Global asax cs doesn t work for you    ToList      Add  ToList   function   I tried out every solution but following worked for me   var allShops   context shops Where s   gt  s city id    id    ToList      return allShops    I hope  it helps

User · Answer

Add the below line   this Configuration ProxyCreationEnabled   false    Two way to use ProxyCreationEnabled as false    Add it inside of DBContext Constructor  public ProductEntities     base  name ProductEntities         this Configuration ProxyCreationEnabled   false       OR   Add the line inside of Get method  public IEnumerable lt Brand Details gt  Get         using  ProductEntities obj   new ProductEntities                  this Configuration ProxyCreationEnabled   false          return obj Brand Details ToList

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There s also this scenario that generate same error   In case of the return being a List lt dynamic gt  to web api method  Example   public HttpResponseMessage Get         var item   new List lt dynamic gt    new TestClass   Name    Ale   Age   30           return Request CreateResponse HttpStatusCode OK  item      public class TestClass       public string Name   get  set        public int Age   get  set        So  for this scenario use the  KnownTypeAttribute  in the return class  all of them  like this    KnownTypeAttribute typeof TestClass    public class TestClass       public string Name   get  set        public int Age   get  set        This works for me

User · Answer

Solution that worked for me    Use  DataContract  for class and  DataMember  attributes for each property to serialize  This is enough to get Json result  for ex  from fiddler   To get xml serialization write in Global asax this code   var xml   GlobalConfiguration Configuration Formatters XmlFormatter  xml UseXmlSerializer   true  Read this article  it helped me to understand serialization  https   www asp net web-api overview formats-and-model-binding json-and-xml-serialization

User · Answer

Given right answer is one way to go  however it is an overkill when you can fix it by one config settings   Better to use it in the dbcontext constructor   public DbContext      dbcontext constructor               base  name ConnectionStringNameFromWebConfig          this Configuration LazyLoadingEnabled   false       this Configuration ProxyCreationEnabled   false      Asp Net Web API Error  The   39 ObjectContent 1  39  type failed to serialize the response body for content type   39 application xml  charset utf-8  39

User · Answer

Visual Studio 2017 or 2019 is totally unthoughtful on this  because Visual Studio itself requires the output to be in json format  while Visual Studio s default format is  XmlFormat   config Formatters XmlFormatter    Visual Studio should do this automatically instead of giving developers so much trouble   To correct this problem  go to the WebApiConfig cs file  and add  var json   config Formatters JsonFormatter        json SerializerSettings PreserveReferencesHandling   Newtonsoft Json PreserveReferencesHandling Objects        config Formatters Remove config Formatters XmlFormatter     after  config MapHttpAttributeRoutes     in the Register HttpConfiguration config  method  This would allow your project to produce json output

User · Answer

Use  Serializable  for class   Example    Serializable  public class UserModel       public string Name  get set       public string Age  get set       It worked for me

User · Answer

To add to jensendp s answer   I would pass the entity to a user created model and use the values from that entity to set the values in your newly created model  For example   public class UserInformation      public string Name   get  set       public int Age   get  set        public UserInformation UserEntity user          this Name   user name        this Age   user age           Then change your return type to  IEnumerable lt UserInformation gt

User · Answer

This also happens when the Response-Type is not public  I returned an internal class as I used Visual Studio to generate me the type   internal class -- gt  public class

User · Answer

in my case  it was fixed when I removed the virtual keyword before my navigation properties  I mean the reference tables  so I changed   public virtual MembershipType MembershipType   get  set      to   public MembershipType MembershipType   get  set

User · Answer

Another case where I received this error was when my database query returned a null value but my user view model type was set as non-nullable   For example  changing my UserModel field from int to int  resolved

User · Answer

You will have to define Serializer Formatter within WebApiConfig cs available in App Start Folder like  Adding config Formatters Remove config Formatters XmlFormatter          which will provide you data in JSON Format  Adding config Formatters Remove config Formatters JsonFormatter          which will provide you data in XML Format

User · Answer

I don t like this code    foreach var user in db Users    As an alternative  one might do something like this  which worked for me   var listOfUsers   db Users Select r   gt  new UserModel                                                         userModel FirstName   r FirstName                               userModel LastName   r LastName                                 return listOfUsers ToList      However  I ended up using Lucas Roselli s solution   Update  Simplified by returning an anonymous object   var listOfUsers   db Users Select r   gt  new                                                          FirstName   r FirstName                               LastName   r LastName                                return listOfUsers ToList

User · Answer

In my case I have had similar error message      The  ObjectContent 1  type failed to serialize the response body for   content type  application xml  charset utf-8     But when I dig deeper in it  the issue was      Type  name SomeSubRootType    with data contract name    SomeSubRootType   schemas datacontract org 2004 07 WhatEverService    is not expected  Consider using a DataContractResolver if you are   using DataContractSerializer or add any types not known statically to   the list of known types - for example  by using the KnownTypeAttribute   attribute or by adding them to the list of known types passed to the   serializer    The way I solved by adding KnownType    KnownType typeof SomeSubRootType    public partial class SomeRootStructureType   This was solved inspired from this answer   Reference  https   msdn microsoft com en-us library ms730167 v vs 100  aspx

User · Answer

While all these answers above are correct  one may want to check the InnerException   ExceptionMessage    If it says something like this  The ObjectContext instance has been disposed and can no longer be used for operations that require a connection    This could be an issue because of default behavior of the EF    By assigning LazyLoadingEnabled   false in your DbContext constructor will do the trick   public class MyDbContext   DbContext     public MyDbContext           this Configuration LazyLoadingEnabled   false          For more detailed reading about EagerLoading and LazyLoading behavior of EF refer this MSDN Article

User · Answer

Use the following namespace   using System Web OData   Instead of    using System Web Http OData   It worked for me

User · Answer

Just put following lines in global asax   GlobalConfiguration Configuration Formatters JsonFormatter SerializerSettings ReferenceLoopHandling   Newtonsoft Json ReferenceLoopHandling Ignore    GlobalConfiguration Configuration Formatters Remove GlobalConfiguration Configuration Formatters XmlFormatter     Import  using System Data Entity

User · Answer

Add this code to global asax below on Application Start   Update from  Ignore to  Serialize   It must work   GlobalConfiguration Configuration Formatters JsonFormatter SerializerSettings ReferenceLoopHandling   Newtonsoft Json ReferenceLoopHandling Serialize              GlobalConfiguration Configuration Formatters Remove GlobalConfiguration Configuration Formatters XmlFormatter

User · Answer

Adding this in your Application Start   method of Global asax file should solve the problem  protected void Application Start         GlobalConfiguration Configuration Formatters JsonFormatter SerializerSettings          ReferenceLoopHandling   Newtonsoft Json ReferenceLoopHandling Ignore      GlobalConfiguration Configuration Formatters          Remove GlobalConfiguration Configuration Formatters XmlFormatter               METHOD 2   Not recommended  If you are working with EntityFramework  you can disable proxy in your DbContext class constructor  NOTE  this code wll be removed if you update the model  public class MyDbContext   DbContext     public MyDbContext           this Configuration ProxyCreationEnabled   false

User · Answer

I basically add one line which they are    entities Configuration ProxyCreationEnabled   false    to UsersController cs   using System  using System Collections Generic  using System Linq  using System Net  using System Net Http  using System Web Http  using UserDataAccess   namespace SBPMS Controllers       public class UsersController   ApiController                 public IEnumerable lt User gt  Get                 using  SBPMSystemEntities entities   new SBPMSystemEntities                      entities Configuration ProxyCreationEnabled   false                  return entities Users ToList                                    public User Get int id                using  SBPMSystemEntities entities   new SBPMSystemEntities                      entities Configuration ProxyCreationEnabled   false                  return entities Users FirstOrDefault e   gt  e user ID    id

User · Answer

My personal favorite  Just add the code below to App Start WebApiConfig cs  This will return json instead of XML by default and also prevent the error you had  No need to edit Global asax to remove XmlFormatter etc      The  ObjectContent 1  type failed to serialize the response body for content type  application xml  charset utf-8   config Formatters JsonFormatter SupportedMediaTypes Add new MediaTypeHeaderValue  text html

User · Answer

Use AutoMapper     public IEnumerable lt User gt  GetAll                 using  Database db   new Database                          var users   AutoMapper Mapper DynamicMap lt List lt User gt  gt  db Users               return users

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