Custom Json java deserializer

· February 18, 2022

json   deserializer   java

We will show two ways to deserialize:

  • Deserializing the whole class.
  • Deserializing by type.

Deserialize whole class:

 
import com.fasterxml.jackson.core.JsonParser;
import com.fasterxml.jackson.databind.DeserializationContext;
import com.fasterxml.jackson.databind.JsonDeserializer;
import com.fasterxml.jackson.databind.JsonNode;
import org.bson.types.ObjectId;
import java.io.IOException;

public class OurClassDeserializer extends JsonDeserializer<OurClass> {
    @Override
    public OurClass deserialize(JsonParser parser, DeserializationContext ctxt) throws IOException {
        JsonNode node = parser.getCodec().readTree(parser);
        
        ObjectId id = new ObjectId(node.get("id").asText());
        String name = node.get("name").asText();
        
        return new OurClass("id", "name");
    }
}

And OurClass:

import org.bson.types.ObjectId;
import com.fasterxml.jackson.databind.annotation.JsonDeserialize;
import OurClassDeserializer;

@JsonDeserialize(using = OurClassDeserializer.class)
public class OurClass {
    ObjectId id;
    String deposits;
}

Deserialize an ObjectId and Money

  • ObjectId:
import com.fasterxml.jackson.core.JsonParser;
import com.fasterxml.jackson.databind.DeserializationContext;
import com.fasterxml.jackson.databind.JsonDeserializer;
import org.bson.types.ObjectId;

import java.io.IOException;

public class ObjectIdDeserializer extends JsonDeserializer<ObjectId> {
    @Override
    public ObjectId deserialize(JsonParser parser, DeserializationContext ctxt) throws IOException {
        return new ObjectId(parser.getValueAsString());
    }
}
  • Money:
import com.fasterxml.jackson.core.JsonParser;
import com.fasterxml.jackson.databind.DeserializationContext;
import com.fasterxml.jackson.databind.JsonDeserializer;
import com.fasterxml.jackson.databind.JsonNode;
import org.javamoney.moneta.Money;

import java.io.IOException;

public class MoneyDeserializer extends JsonDeserializer<Money> {

    @Override
    public Money deserialize(JsonParser parser, DeserializationContext ctxt) throws IOException {
        JsonNode node = parser.getCodec().readTree(parser);
        return Money.of(
                Float.valueOf(node.get("value").asText()),
                node.get("currency").asText());
    }
}

And OurClass:

import com.fasterxml.jackson.databind.annotation.JsonDeserialize;
MoneyDeserializer;
ObjectIdDeserializer;
import lombok.AccessLevel;
import lombok.AllArgsConstructor;
import lombok.Builder;
import lombok.NoArgsConstructor;
import lombok.Value;
import org.bson.types.ObjectId;
import org.javamoney.moneta.Money;

@Value
@Builder
@NoArgsConstructor(force = true, access = AccessLevel.PRIVATE)
@AllArgsConstructor
public class OurClass {
    @JsonDeserialize(using = ObjectIdDeserializer.class) ObjectId id;
    @JsonDeserialize(using = MoneyDeserializer.class) Money money;
}

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