JSON NET Error Self referencing loop detected for type

Question

I tried to serialize POCO class that was automatically generated from Entity Data Model  edmx and when I used JsonConvert SerializeObject   I got the following error   Error Self referencing loop detected for type System data entity occurs   How do I solve this problem

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In  Net 5 x  update your ConfigureServices method in startup cs with the below code public void ConfigureServices IServiceCollection services        ----------------     ----------------     services AddMvc   AddJsonOptions options   gt                options JsonSerializerOptions ReferenceHandler   ReferenceHandler Preserve              ------------------    By default  serialization  System Text Json Serialization  does not support objects with cycles and does not preserve duplicate references  Use Preserve to enable unique object reference preservation on serialization and metadata consumption to read preserved references on deserialization  MSDN Link

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People have already talked about  JsonIgnore  being added to the virtual property in the class  for example    JsonIgnore  public virtual Project Project   get  set      I will also share another option   JsonProperty NullValueHandling   NullValueHandling Ignore   which omits the property from serialization only if it is null     JsonProperty NullValueHandling   NullValueHandling Ignore   public virtual Project Project   get  set

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To ignore loop references and not to serialize them globally in MVC 6 use the following in startup cs       public void ConfigureServices IServiceCollection services                services AddMvc   Configure lt MvcOptions gt  options   gt                        options OutputFormatters RemoveTypesOf lt JsonOutputFormatter gt                 var jsonOutputFormatter   new JsonOutputFormatter                jsonOutputFormatter SerializerSettings ReferenceLoopHandling   Newtonsoft Json ReferenceLoopHandling Ignore              options OutputFormatters Insert 0  jsonOutputFormatter

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Use JsonSerializerSettings  ReferenceLoopHandling Error  default  will error if a reference loop is encountered  This is why you get an exception  ReferenceLoopHandling Serialize is useful if objects are nested but not indefinitely  ReferenceLoopHandling Ignore will not serialize an object if it is a child object of itself   Example  JsonConvert SerializeObject YourPOCOHere  Formatting Indented   new JsonSerializerSettings             ReferenceLoopHandling   ReferenceLoopHandling Serialize      Should you have to serialize an object that is nested indefinitely you can use PreserveObjectReferences to avoid a StackOverflowException  Example  JsonConvert SerializeObject YourPOCOHere  Formatting Indented   new JsonSerializerSettings             PreserveReferencesHandling   PreserveReferencesHandling Objects      Pick what makes sense for the object you are serializing  Reference http   james newtonking com json help

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In  NET Core 1 0  you can set this as a global setting in your Startup cs file   using System Buffers  using Microsoft AspNetCore Mvc Formatters  using Newtonsoft Json      beginning of Startup class      public void ConfigureServices IServiceCollection services                services AddMvc options   gt                        options OutputFormatters Clear                options OutputFormatters Add new JsonOutputFormatter new JsonSerializerSettings                    ReferenceLoopHandling   ReferenceLoopHandling Ignore                 ArrayPool lt char gt  Shared

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If you re using  NET Core 2 x  update your ConfigureServices section in Startup cs  https   docs microsoft com en-us ef core querying related-data related-data-and-serialization      public void ConfigureServices IServiceCollection services                     services AddMvc            AddJsonOptions              options   gt  options SerializerSettings ReferenceLoopHandling   Newtonsoft Json ReferenceLoopHandling Ignore                             If you re using  NET Core 3 x without MVC  it would be   services AddControllers      AddNewtonsoftJson options   gt        options SerializerSettings ReferenceLoopHandling   Newtonsoft Json ReferenceLoopHandling Ignore         This reference loop handling is almost mandatory if you re using Entity Framework and database-first design pattern

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Just update services AddControllers   in Startup cs file services AddControllers      AddNewtonsoftJson options   gt        options SerializerSettings ReferenceLoopHandling   Newtonsoft Json ReferenceLoopHandling Ignore

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You can apply an attribute to the property too   The  JsonProperty  ReferenceLoopHandling          attribute is well suited to this   For example        lt summary gt      Represents the exception information of an event      lt  summary gt  public class ExceptionInfo             code omitted for brevity              lt summary gt          An inner  nested  error           lt  summary gt       JsonProperty  ReferenceLoopHandling   ReferenceLoopHandling Ignore  IsReference   true        public ExceptionInfo Inner   get  set               code omitted for brevity            Hope that helps  Jaans

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The simplest way to do this is to install Json NET  from nuget and add the  JsonIgnore  attribute to the virtual property in the class  for example       public string Name   get  set        public string Description   get  set        public Nullable lt int gt  Project ID   get  set          JsonIgnore      public virtual Project Project   get  set      Although these days  I create a model with only the properties I want passed through so it s lighter  doesn t include unwanted collections  and I don t lose my changes when I rebuild the generated files

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I ve inherited a database application that serves up the data model to the web page   Serialization by default will attempt to traverse the entire model tree and most of the answers here are a good start on how to prevent that  One option that has not been explored is using interfaces to help   I ll steal from an earlier example  public partial class CompanyUser       public int Id   get  set        public int CompanyId   get  set        public int UserId   get  set         public virtual Company Company   get  set         public virtual User User   get  set       public interface IgnoreUser        JsonIgnore      User User   get  set       public interface IgnoreCompany        JsonIgnore      User User   get  set       public partial class CompanyUser   IgnoreUser  IgnoreCompany      No Json settings get harmed in the above solution   Setting the LazyLoadingEnabled and or the ProxyCreationEnabled to false impacts all your back end coding and prevents some of the true benefits of an ORM tool   Depending on your application the LazyLoading ProxyCreation settings can prevent the navigation properties loading without manually loading them  Here is a much  much better solution to prevent navigation properties from serializing and it uses standard json functionality  How can I do JSON serializer ignore navigation properties

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I was facing the same problem and I tried using JsonSetting to ignore the self-referencing error its kinda work until I got a class which self-referencing very deeply and my dot-net process hangs on Json writing value   My Problem      public partial class Company   BaseModel       public Company                 CompanyUsers   new HashSet lt CompanyUser gt                public string Name   get  set         public virtual ICollection lt CompanyUser gt  CompanyUsers   get  set       public partial class CompanyUser       public int Id   get  set        public int CompanyId   get  set        public int UserId   get  set         public virtual Company Company   get  set         public virtual User User   get  set       public partial class User   BaseModel       public User                 CompanyUsers   new HashSet lt CompanyUser gt                public string DisplayName   get  set        public virtual ICollection lt CompanyUser gt  CompanyUsers   get  set         You can see the problem in User class it s referencing to CompanyUser class which is a self-referencing    Now  I m calling the GetAll Method which includes all the relational properties   cs GetAll  CompanyUsers    CompanyUsers User      On this stage my DotNetCore process hangs on Executing JsonResult  writing value     and never come  In my Startup cs  I ve already set the JsonOption  For some reason EFCore is including nested property which I m not asking Ef to give       options SerializerSettings ReferenceLoopHandling   Newtonsoft Json ReferenceLoopHandling Ignore    expected behavior should be this     Hey EfCore can you please include  CompanyUsers  data as well in my   Company class so that i can easily access the data    then     Hey EfCore can you also please include the  CompanyUsers User  data as   well so that i can easily access the data like this   Company CompanyUsers First   User DisplayName   at this stage i should only get this  Company CompanyUsers First   User DisplayName  and it should not give me Company CompanyUsers First   User CompanyUsers which causing the self-referencing issue  Technically it shouldn t give me User CompanyUsers as CompanyUsers is a navigational property  But  EfCore get very excited and giving me User CompanyUsers   So  I decided to write an extension method for property to be excluded from the object  it s actually not excluding it s just setting the property to null   Not only that it will also work on array properties as well  below is the code I m also going to export the nuget package for other users  not sure if this even helps someone   Reason is simple because I m too lazy to write  Select n    new   n p1  n p2    I just don t want to write select statement to exclude only 1 property    This is not the best code  I ll update at some stage  as I have written in a hurry and though this might help someone who wants to exclude  set null  in the object with arrays also       public static class PropertyExtensions       public static void Exclude lt T gt  this T obj  Expression lt Func lt T  object gt  gt  expression                var visitor   new PropertyVisitor lt T gt             visitor Visit expression Body           visitor Path Reverse            List lt MemberInfo gt  paths   visitor Path          Action lt List lt MemberInfo gt   object gt  act   null           int recursiveLevel   0          act    List lt MemberInfo gt  vPath  object vObj    gt                            set last propert to null thats what we want to avoid the self-referencing error              if  recursiveLevel    vPath Count - 1                                if  vObj    null  throw new ArgumentNullException  Object cannot be null                     vObj GetType   GetMethod   set  vPath ElementAt recursiveLevel  Name    Invoke vObj  new object     null                     return                             var pi   vObj GetType   GetProperty vPath ElementAt recursiveLevel  Name               if  pi    null  return              var pv   pi GetValue vObj  null               if  pi PropertyType IsArray    pi PropertyType Name Contains  HashSet 1      pi PropertyType Name Contains  ICollection 1                                  var ele    IEnumerator pv GetType   GetMethod  GetEnumerator   Invoke pv  null                    while  ele MoveNext                                          recursiveLevel                        var arrItem   ele Current                       act vPath  arrItem                        recursiveLevel--                                     if  recursiveLevel    0  recursiveLevel--                  return                            else                               recursiveLevel                    act vPath  pv                              if  recursiveLevel    0  recursiveLevel--                          check if the root level propert is array         if  obj GetType   IsArray                        var ele    IEnumerator obj GetType   GetMethod  GetEnumerator   Invoke obj  null               while  ele MoveNext                                  recursiveLevel   0                  var arrItem   ele Current                   act paths  arrItem                                   else                       recursiveLevel   0              act paths  obj                         public static T Explode lt T gt  this T   obj                return obj FirstOrDefault               public static T Explode lt T gt  this ICollection lt T gt  obj                return obj FirstOrDefault              above extension class will give you the ability to set the property to null to avoid the self-referencing loop even arrays   Expression Builder      internal class PropertyVisitor lt T gt    ExpressionVisitor       public readonly List lt MemberInfo gt  Path   new List lt MemberInfo gt          public Expression Modify Expression expression                return Visit expression               protected override Expression VisitMember MemberExpression node                if    node Member is PropertyInfo                         throw new ArgumentException  The path can only contain properties   nameof node                       Path Add node Member           return  base VisitMember node             Usages   Model Classes      public class Person       public string Name   get  set        public Address AddressDetail   get  set       public class Address       public string Street   get  set        public Country CountryDetail   get  set        public Country   CountryDetail2   get  set       public class Country       public string CountryName   get  set        public Person   CountryDetail   get  set        Dummy Data             var p   new Person                       Name    Adeel Rizvi               AddressDetail   new Address                               Street    Sydney                   CountryDetail   new Country                                       CountryName    AU                                                      var p1   new Person                       Name    Adeel Rizvi               AddressDetail   new Address                               Street    Sydney                   CountryDetail2   new Country                                         new Country  CountryName    AU   CountryDetail   new Person    new Person   Name    A1     new Person   Name    A1     new Person   Name    A1                             new Country  CountryName    AU   CountryDetail   new Person    new Person   Name    A2     new Person   Name    A1     new Person   Name    A1                             new Country  CountryName    AU   CountryDetail   new Person    new Person   Name    A3     new Person   Name    A1     new Person   Name    A1                             new Country  CountryName    AU   CountryDetail   new Person    new Person   Name    A4     new Person   Name    A1     new Person   Name    A1                             new Country  CountryName    AU   CountryDetail   new Person    new Person   Name    A5     new Person   Name    A1     new Person   Name    A1                             new Country  CountryName    AU   CountryDetail   new Person    new Person   Name    A6     new Person   Name    A1     new Person   Name    A1                             new Country  CountryName    AU   CountryDetail   new Person    new Person   Name    A7     new Person   Name    A1     new Person   Name    A1                             new Country  CountryName    AU   CountryDetail   new Person    new Person   Name    A8     new Person   Name    A1     new Person   Name    A1                             new Country  CountryName    AU   CountryDetail   new Person    new Person   Name    A9     new Person   Name    A1     new Person   Name    A1                             new Country  CountryName    AU   CountryDetail   new Person    new Person   Name    A1     new Person   Name    A1     new Person   Name    A1                             new Country  CountryName    AU   CountryDetail   new Person    new Person   Name    A2     new Person   Name    A1     new Person   Name    A1                             new Country  CountryName    AU   CountryDetail   new Person    new Person   Name    A3     new Person   Name    A1     new Person   Name    A1                             new Country  CountryName    AU   CountryDetail   new Person    new Person   Name    A4     new Person   Name    A1     new Person   Name    A1                             new Country  CountryName    AU   CountryDetail   new Person    new Person   Name    A5     new Person   Name    A1     new Person   Name    A1                             new Country  CountryName    AU   CountryDetail   new Person    new Person   Name    A6     new Person   Name    A1     new Person   Name    A1                             new Country  CountryName    AU   CountryDetail   new Person    new Person   Name    A7     new Person   Name    A1     new Person   Name    A1                             new Country  CountryName    AU   CountryDetail   new Person    new Person   Name    A8     new Person   Name    A1     new Person   Name    A1                             new Country  CountryName    AU   CountryDetail   new Person    new Person   Name    A9     new Person   Name    A1     new Person   Name    A1                                                       Cases   Case 1  Exclude only property without any array  p Exclude n   gt  n AddressDetail CountryDetail CountryName     Case 2  Exclude property with 1 array   p1 Exclude n   gt  n AddressDetail CountryDetail2 Explode   CountryName     Case 3  Exclude property with 2 nested array  p1 Exclude n   gt  n AddressDetail CountryDetail2 Explode   CountryDetail Explode   Name     Case 4  EF GetAll Query With Includes  var query   cs GetAll  CompanyUsers    CompanyUsers User   ToArray    query Exclude n   gt  n Explode   CompanyUsers Explode   User CompanyUsers   return query    You have notice that Explode   method its also a extension method just for our expression builder to get the property from array property  Whenever there is a array property use the  Explode   YourPropertyToExclude or  Explode   Property1 MyArrayProperty Explode   MyStupidProperty  Above code helps me to avoid the self-referencing so deep as deep i want  Now i can use GetAll and exclude the property which i don t want   Thank you for reading this big post

User · Answer

Simply place Configuration ProxyCreationEnabled   false  inside the context file  this will solve the problem   public demEntities         base  name demEntities         Configuration ProxyCreationEnabled   false

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The fix is to ignore loop references and not to serialize them  This behaviour is specified in JsonSerializerSettings   Single JsonConvert with an overload   JsonConvert SerializeObject YourObject  Formatting Indented      new JsonSerializerSettings             ReferenceLoopHandling   Newtonsoft Json ReferenceLoopHandling Ignore            Global Setting with code in Application Start   in Global asax cs   JsonConvert DefaultSettings        gt  new JsonSerializerSettings        Formatting   Newtonsoft Json Formatting Indented       ReferenceLoopHandling   Newtonsoft Json ReferenceLoopHandling Ignore      Reference  https   github com JamesNK Newtonsoft Json issues 78

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Team   This works with ASP NET Core  The challenge to the above is how you  set the setting to ignore    Depending on how you setup your application it can be quite challenging  Here is what worked for me    This can be placed in your public void ConfigureServices IServiceCollection services  section   services AddMvc   AddJsonOptions opt   gt                    opt SerializerSettings ReferenceLoopHandling         Newtonsoft Json ReferenceLoopHandling Ignore

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I liked the solution that does it from Application Start   as in the answer here Apparently I could not access the json objects in JavaScript using the configuration within my function  as in DalSoft s answer as the object returned had  quot  n  r quot  all over the  key  val  of the object  Anyway whatever works is great  because different approaches work in different scenario based on the comments and questions asked  though a standard way of doing it would be preferable with some good documentation supporting the approach

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Please also make sure to use await and async in you method  You can get this error if your object are not serialized properly

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I had this exception and my working solution is Easy and Simple   Ignore the Referenced property by adding the JsonIgnore attribute to it    JsonIgnore  public MyClass currentClass   get  set      Reset the property when you Deserialize it   Source   JsonConvert DeserializeObject lt MyObject gt  JsonTxt   foreach  var item in Source                        Source MyClass   item              using Newtonsoft Json

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Use this in WebApiConfig cs class     var json   config Formatters JsonFormatter  json SerializerSettings PreserveReferencesHandling   Newtonsoft Json PreserveReferencesHandling Objects  config Formatters Remove config Formatters XmlFormatter

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For  NET Core 3 0  update the Startup cs class as shown below   public void ConfigureServices IServiceCollection services         services AddControllers        AddNewtonsoftJson          options   gt  options SerializerSettings ReferenceLoopHandling   Newtonsoft Json ReferenceLoopHandling Ignore                 See  https   devblogs microsoft com aspnet asp-net-core-updates-in-net-core-3-0-preview-5

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C  code               var jsonSerializerSettings   new JsonSerializerSettings                               ReferenceLoopHandling   ReferenceLoopHandling Serialize                  PreserveReferencesHandling   PreserveReferencesHandling Objects                              var jsonString   JsonConvert SerializeObject object2Serialize  jsonSerializerSettings                var filePath     E  json json                File WriteAllText filePath  jsonString

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To serialize usin NEWTONSOFTJSON when you have loop issue  in my case I did not need modify global asax or either apiconfig  I just use JsonSerializesSettings ignoring Looping handling   JsonSerializerSettings jss   new JsonSerializerSettings    jss ReferenceLoopHandling   ReferenceLoopHandling Ignore  var lst   db shCards Where m   gt  m CardID    id  ToList    string json   JsonConvert SerializeObject lst  jss

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Fix 1  Ignoring circular reference globally  I have chosen tried this one  as have many others  The json net serializer has an option to ignore circular references  Put the following code in WebApiConfig cs file   config Formatters JsonFormatter SerializerSettings ReferenceLoopHandling    Newtonsoft Json ReferenceLoopHandling Ignore    The simple fix will make serializer to ignore the reference which will cause a loop  However  it has limitations   The data loses the looping reference information The fix only applies to JSON net The level of references can t be controlled if there is a deep reference chain  If you want to use this fix in a non-api ASP NET project  you can add the above line to Global asax cs  but first add  var config   GlobalConfiguration Configuration   If you want to use this in  Net Core project  you can change Startup cs as    var mvc   services AddMvc options   gt                                               AddJsonOptions x   gt  x SerializerSettings ReferenceLoopHandling   Newtonsoft Json ReferenceLoopHandling Ignore    Fix 2  Preserving circular reference globally This second fix is similar to the first  Just change the code to  config Formatters JsonFormatter SerializerSettings ReferenceLoopHandling         Newtonsoft Json ReferenceLoopHandling Serialize       config Formatters JsonFormatter SerializerSettings PreserveReferencesHandling         Newtonsoft Json PreserveReferencesHandling Objects   The data shape will be changed after applying this setting                quot  id quot   quot 1 quot          quot Category quot              quot  id quot   quot 2 quot             quot Products quot                                  quot  id quot   quot 3 quot                   quot Category quot                       quot  ref quot   quot 2 quot                                    quot Id quot  2                  quot Name quot   quot Yogurt quot                                               quot  ref quot   quot 1 quot                                      quot Id quot  1            quot Name quot   quot Diary quot                  quot Id quot  1         quot Name quot   quot Whole Milk quot                    quot  ref quot   quot 3 quot          The  id and  ref keeps the all the references and makes the object graph level flat  but the client code needs to know the shape change to consume the data and it only applies to JSON NET serializer as well  Fix 3  Ignore and preserve reference attributes This fix is decorate attributes on model class to control the serialization behavior on model or property level  To ignore the property   public class Category                 public int Id   get  set             public string Name   get  set                      JsonIgnore            IgnoreDataMember           public virtual ICollection lt Product gt  Products   get  set             JsonIgnore is for JSON NET and IgnoreDataMember is for XmlDCSerializer  To preserve reference      Fix 3           JsonObject IsReference   true            public class Category                         public int Id   get  set                 public string Name   get  set                             Fix 3                JsonIgnore                 IgnoreDataMember              public virtual ICollection lt Product gt  Products   get  set                                DataContract IsReference   true           public class Product                        Key              public int Id   get  set                          DataMember              public string Name   get  set                          DataMember              public virtual Category Category   get  set               JsonObject IsReference   true   is for JSON NET and  DataContract IsReference   true   is for XmlDCSerializer  Note that  after applying DataContract on class  you need to add DataMember to properties that you want to serialize  The attributes can be applied on both json and xml serializer and gives more controls on model class

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We can add these two lines into DbContext class constructor to disable Self referencing loop  like  public TestContext             base  name TestContext         this Configuration LazyLoadingEnabled   false      this Configuration ProxyCreationEnabled   false

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For not looping this worked for me- ReferenceLoopHandling   ReferenceLoopHandling Ignore   I ve solved it all here - Entity Framework children serialization with  Net Core 2 WebAPI  https   gist github com Kaidanov f9ad0d79238494432f32b8407942c606  Will appreciate any remarks  maybe someone can use it sometime

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My Problem Solved With Custom Config JsonSerializerSettings   services AddMvc                            AddJsonOptions opt   gt                                     opt SerializerSettings ReferenceLoopHandling                       Newtonsoft Json ReferenceLoopHandling Serialize                  opt SerializerSettings PreserveReferencesHandling                       Newtonsoft Json PreserveReferencesHandling Objects

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For me I had to go a different route   Instead of trying to fix the JSON Net serializer I had to go after the Lazy Loading on my datacontext     I just added this to my base repository   context Configuration ProxyCreationEnabled   false    The  context  object is a constructor parameter I use in my base repository because I use dependency injection   You could change the ProxyCreationEnabled property anywhere you instantiate your datacontext instead   http   techie-tid-bits blogspot com 2015 09 jsonnet-serializer-and-error-self html

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