Avro SerializationException: Type is not supported by the resolver

Today in this article, we will cover below aspects,

Issue Description

Avro schema serialization or conversion produces the below error,

System.Runtime.Serialization.SerializationException: 'Type 'AvrosampleNetCore.AccountDetails' is not supported by the resolver.'

I was using AvroSerializer using Microsoft.Hadoop.Avro2 .

Resolution

I came across this issue while converting a type to create Avro schema details.

Below is the type used for the conversion,

 class AccountDetails
    {
        public int AccountId { get; set; }
        public string AccountName { get; set; }
        [NullableSchema]
        public SubAccounts[] Accounts { get; set; }
    }


    public class SubAccounts
    {
        public int AccountId { get; set; }
        [NullableSchema]
        public string AccountType { get; set; }
    }

I was using AvroSerializer using Microsoft.Hadoop.Avro2

var result = AvroSerializer.Create<AccountDetails>(settings).WriterSchema.ToString();

I was able to fix the issue using any of the below approaches.

Approach I – Specify schema resolver

I was able to resolve the issue by specifying AvroSerializerSettings using AvroPublicMemberContractResolver while creating the schema.

            AvroSerializerSettings settings = new AvroSerializerSettings();
            settings.Resolver = new AvroPublicMemberContractResolver();
 
            var result = AvroSerializer.Create<AccountDetails> 
            (settings).WriterSchema.ToString();

This option does not require you to specify the [DataContract] or [DataMember] attribute to your class definition.

After executing the above I was able to resolve the error successfully.

Approach II – Specify attributes [DataContract] and [DataMember]

I was also able to resolve the issue by specifying the [DataContract] or [DataMember] attribute to the class definition.

   

    [DataContract]
    class AccountDetails
    {
        [DataMember]
        public int AccountId { get; set; }
        [DataMember]
        public string AccountName { get; set; }
        [DataMember]
        [NullableSchema]
        public SubAccounts[] Accounts { get; set; }
    }

    [DataContract]
    public class SubAccounts
    {
         [DataMember]
        public int AccountId { get; set; }
        [NullableSchema]
        [DataMember]
        public string AccountType { get; set; }
    }

The below code generates the schema successfully,

var result = AvroSerializer.Create<AccountDetails>().WriterSchema.ToString();

Did I miss anything else in these resolution steps?

Did the above steps resolve your issue? Please sound off your comments below!

Happy Coding !!

References:

• Generate Avro Schema from JSON

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