[Solved-5 Solutions] Error Self referencing loop detected for type System.data.entity occurs
Error Description:
- When we try to serialize POCO class that was automatically generated from Entity Data Model .edmx and when we use
JsonConvert.SerializeObject
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- We get the following error:
Error Self referencing loop detected for type System.data.entity
Solution 1:
Ignoring circular reference globally
- json.net serializer supports to ignore circular reference on global setting. A quick fix is to put following code in WebApiConfig.cs file:
config.Formatters.JsonFormatter.SerializerSettings.ReferenceLoopHandling
= Newtonsoft.Json.ReferenceLoopHandling.Ignore;
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- 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 this fix only applies to JSON.net The level of references can't be controlled if there is a deep reference chain.
Solution 2:
- Just change the code to:
config.Formatters.JsonFormatter.SerializerSettings.ReferenceLoopHandling
= Newtonsoft.Json.ReferenceLoopHandling.Serialize;
config.Formatters.JsonFormatter.SerializerSettings.PreserveReferencesHandling
= Newtonsoft.Json.PreserveReferencesHandling.Objects;
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- The data shape will be changed after applying this setting.
[
{
"$id":"1",
"Category":{
"$id":"2",
"Products":[
{
"$id":"3",
"Category":{
"$ref":"2"
},
"Id":2,
"Name":"Yogurt"
},
{
"$ref":"1"
}
],
"Id":1,
"Name":"Diary"
},
"Id":1,
"Name":"Whole Milk"
},
{
"$ref":"3"
}
]
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- The $id and $ref keeps 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.
Solution 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<Product> Products { get; set; }
}
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- 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<Product> 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; }
}
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JsonObject(IsReference = true)]is for JSON.NET and[DataContract(IsReference = true)]is for XmlDCSerializer. Note that: after applyingDataContracton class, we need to addDataMemberto properties that you want to serialize.- The attributes can be applied on both json and xml serializer and gives more controls on model class.
Solution 4:
Use JsonSerializerSettings
ReferenceLoopHandling.Error(default) will error if a reference loop is encountered. This is why you get an exception.ReferenceLoopHandling.Serializeis useful if objects are nested but not indefinitely.ReferenceLoopHandling.Ignorewill not serialize an object if it is a child object of itself.
Example:
JsonConvert.SerializeObject(YourPOCOHere, Formatting.Indented,
new JsonSerializerSettings {
ReferenceLoopHandling = ReferenceLoopHandling.Serialize
}); click below button to copy the code. By - json tutorial - team
- We should have to serialize an object that is nested indefinitely you can use PreserveObjectReferences to avoid Exception.
Example:
JsonConvert.SerializeObject(YourPOCOHere, Formatting.Indented,
new JsonSerializerSettings {
PreserveReferencesHandling = PreserveReferencesHandling.Objects
}); click below button to copy the code. By - json tutorial - team
Solution 5:
- 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;
}