@RestController with @ModelAttribute using custom setters

Question

I have my @RestController, that has his parameters mapped in @ModelAttribute to shorten the list of parameters. However, some of the attributes have to translate to custom objects (i.e. Long -> Instant). My question is there a way to make spring use my setters to set those objects?

Controller mapping

@GetMapping("/v1/my/path")
public Collection<Dto> getAll(@ModelAttribute MyRequest request) {
    return someSevice.doSomething(request);
}

ModelAttribute class

public class MyRequest {
    private Instant startTime;
    private Instant endTime;
    private ZoneId timezone;

    // How can make spring use this setter to set start time?
    private void setStartTimeFromLong(Long startTime) {
        this.startTime = Instant.ofEpochSecond(startTime);
    }
}

[A custom `InitBinder` editor](https://stackoverflow.com/questions/5211323/what-is-the-purpose-of-init-binder-in-spring-mvc) might be the most direct approach here. That said, since this is a `GET`, the usual model is for the "request" to be a set of query parameters, and I suggest examining the existing Spring support for Querydsl as an MVC parameter. — chrylis -cautiouslyoptimistic-, Aug 31 '19 at 18:55

score 1 · Accepted Answer · edited Aug 31 '19 at 18:58

1

You always can use custom deserialization for your objects

Check next link

public class ItemDeserializer extends StdDeserializer<Item> {

    public ItemDeserializer() {
        this(null);
    }

    public ItemDeserializer(Class<?> vc) {
        super(vc);
    }

    @Override
    public Item deserialize(JsonParser jp, DeserializationContext ctxt)
            throws IOException, JsonProcessingException {
        JsonNode node = jp.getCodec().readTree(jp);
        int id = (Integer) ((IntNode) node.get("id")).numberValue();
        String itemName = node.get("itemName").asText();
        int userId = (Integer) ((IntNode) node.get("createdBy")).numberValue();

        return new Item(id, itemName, new User(userId, null));
    }
}

edited Aug 31 '19 at 18:58

Alan Sereb

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answered Aug 31 '19 at 18:36

Ihar Sadounikau

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This is a GET request, not all libraries support JSON payload with GET requests. Your solution will work with JSON payload if you are using Jackson. Unfortunately, I cant use JSON in this case. I appreciate your help! – Alan Sereb Aug 31 '19 at 18:46
Have you tried? :) Jackson with spring works not only for JSON body vales – Ihar Sadounikau Aug 31 '19 at 18:50
2

This is _Jackson serialization_, which would work if the OP were using `@RequestBody` and JSON, but does not apply to `@ModelAttribute`. – chrylis -cautiouslyoptimistic- Aug 31 '19 at 18:51
I have not, you are right. But, @chrylis, has the same opinion. – Alan Sereb Aug 31 '19 at 18:51
@chrylis could you please provide a link to the documentation? I will be helpful :) – Ihar Sadounikau Aug 31 '19 at 19:00

score 0 · Answer 2 · answered Aug 31 '19 at 18:41

0

Implementing your own converter seems to be the best solution for this problem, since there is no way to annotate a setter to be used for populating @ModuleAttribute.

@Component
public class StringToInstantConverter implements Converter<String, Instant> {

    @Override
    public Instant convert(String epochSeconds) {
        return Instant.ofEpochSecond(Long.valueOf(epochSeconds));
    }
}

answered Aug 31 '19 at 18:41

Alan Sereb

2,358
2
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31

It's a nice way, but you have to be careful, you can get unexpected converter issues for other objects – Ihar Sadounikau Aug 31 '19 at 18:48
Agreed, every time I will expect `Instant`, the `String` will be converted to `Long` and then to `Instant`. – Alan Sereb Aug 31 '19 at 18:50

@RestController with @ModelAttribute using custom setters

2 Answers2