java convert map to pojo ignore some keys

Question

I have a map that unsure it keys,but I am sure the keys contains all the pojo fields, says:

public class MyPojo{ 
    String name,
    String addr
}
//map contains keys that not in MyPojo field,e.g. age
map = {"name":"john","addr":"sf school","age":"21"}

In Java how can I can convert it to pojo MyPojo instance? the following method throw exception:

final ObjectMapper mapper = new ObjectMapper(); // jackson's objectmapper
final MyPojo pojo = mapper.convertValue(map, MyPojo.class);

*but sure the keys contains the pojo fields* actually what is pojo field in your understanding? — Antoniossss, Oct 19 '18 at 12:49
Possible duplicate of [Collecting unknown properties with Jackson](https://stackoverflow.com/questions/31164625/collecting-unknown-properties-with-jackson) — Antoniossss, Oct 19 '18 at 12:50
Disabling the feature may make it work: `final ObjectMapper mapper = new ObjectMapper().disable(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES)` — ernest_k, Oct 19 '18 at 12:52

score 8 · Accepted Answer · answered Oct 19 '18 at 12:54

You can use @JsonIgnoreProrperties by Jackson in your MyPojo class. The exception is cause of ObjectMapper not being able to find exact mapping in your MyPojo class.

The API is provided in the same library, that of ObjectMapper.

So here is what your class should look like:

@JsonIgnoreProperties(ignoreUnknown = true)
public class MyPojo{
   String name;
   String addr;
   //Other variables
}

To import it in your code, you need to add the following:

import com.fasterxml.jackson.annotation.JsonIgnoreProperties;

I hope this solves your problem and thisis exactly what you're looking for.

score 1 · Answer 2 · answered Sep 24 '20 at 05:15

As you are working on generics keys(previously unknown), there might be chances of keys(attribute names) present in the map as a key doesn't present in POJO as an attribute. So, set below properties to false, when you create an ObjectMapper instance, so that any unknown or missing attributes wouldn't throw any exceptions.

        final ObjectMapper mapper = new ObjectMapper(); // jackson's objectmapper
        mapper.configure(DeserializationFeature.FAIL_ON_IGNORED_PROPERTIES, false);
        mapper.configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false);

java convert map to pojo ignore some keys

2 Answers2