Spring REST: Appropriate constructor for nested XML request body?

Question

I have a REST callback service that must consume XML in the following format:

<SearchRequest>
  <SearchCriteria>
    <Param1></Param2>
    <Param2></Param2>
  </SearchCriteria>
</SearchRequest>

The actual XML has about 32 parameters within "Criteria", but this gives the basic idea.

I created a SearchRequest class that has the attribute, searchCriteria, and a SearchCriteria class that has param1 and param2.

My REST controller class looks something like this:

import org.springframework.beans.factory.annotation.Value;
import org.springframework.http.HttpStatus;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RequestHeader;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RestController;

@RestController
@RequestMapping("/acme/request/search")
public class AcmeCallbackController {
    @RequestMapping(method = RequestMethod.POST, consumes = "application/xml")
    public ResponseEntity<String> postAcmeSearch(@RequestBody SearchRequest body) {
        StringBuffer resultBuffer = new StringBuffer(2048);
        // implementation code here, 'body' now expected to be a SearchRequest object contructed from request body XML
        return new ResponseEntity<String>(resultBuffer.toString(), HttpStatus.OK);
    }

When I test the above service I receive the following error response:

`{   "timestamp": 1514390248822,
"status": 400,
"error": "Bad Request",
"exception":  org.springframework.http.converter.HttpMessageNotReadableException",
"message": "JSON parse error: Can not construct instance of SearchRequest: no suitable constructor found, can not deserialize from Object value (missing default constructor or creator, or perhaps need to add/enable type information?); nested exception is com.fasterxml.jackson.databind.JsonMappingException: Can not construct instance of SearchRequest: no suitable constructor found, can not deserialize from Object value (missing default constructor or creator, or perhaps need to add/enable type information?)\n at [Source: java.io.PushbackInputStream@26bd9717; line: 2, column: 3]",
"path": "/acme/request/search" }`

Does anyone know the suitable constructor and / or annotations to apply to SearchRequest, so that the xml request is correctly deserialized? I have @JsonProperty("{Attribute}") on all the getters and setters, where {Attribute} is the name of the attribute with an initial cap to match the XML element name, and a constructor that has an argument for each attribute value.

TIA, Ed

Can you share your SearchRequest class, do you have any parameterized constructor defined in the class, if yes then add default constructor as well. — Amit K Bist, Dec 27 '17 at 21:23
Look for solutions to the JsonMappingExceptions, like https://stackoverflow.com/questions/7625783/jsonmappingexception-no-suitable-constructor-found-for-type-simple-type-class?rq=1, https://stackoverflow.com/questions/12750681/cannot-construct-instance-of-jackson — tkruse, Dec 28 '17 at 01:11

score 0 · Answer 1 · answered Dec 28 '17 at 04:46

I figured it out. I had to add annotations to the constructor arguments, e.g.

public SearchRequest(@JsonProperty("Param1") String param1,
        @JsonProperty("Param2") String param2) {
    this.param1 = param1;
    this.param2 = param2;
}

It worked fine after that.

Spring REST: Appropriate constructor for nested XML request body?

1 Answers1