Pass JSON Array to Spring Controller

Question

I need to pass an array of an object to my controller. I'm trying to use @RequestBody like is described in the example here:

http://java2practice.com/2013/03/14/how-to-pass-json-object-string-or-jsonarray-string-from-javascript-to-spring-controller/

I've replicated the example in my project but I get a "bad request" error whenever I call it. I suspect this is because I'm using Spring 4 and Jackson 2 but I'm at a loss how to get it working.

Should this work in this environment? Is there a better way to do this?

Can you post the contents of the logs when the request fails? — geoand
– geoand, Commented Aug 29, 2014 at 16:11

Edward Smith · Accepted Answer · 2014-08-29 20:34:04Z

1

Yes this should work in that environment (that is, using those versions of Spring and Jackson!). When faced with a mystery error like that my go-to is to crank up the log settings to TRACE for whatever library is failing.

I set up this example in my IDE (using Spring4 and Jackson2 as you are), and I immediately encountered a 400 "bad request" error as well. I cranked up the debug settings on org.springframework.web and com.fasterxml.jackson.core to find that Jackson2 was spitting out an exception:

com.fasterxml.jackson.databind.JsonMappingException: Can not deserialize instance of ca.ted.TestController$Person[] out of START_OBJECT token

This was because of the JSON being fed to the jQuery.ajax() call. I removed the "persons":{} object wrapping the array and sent only the array instead:

var arr = [ 
            {
                "firstName" : "Ramesh",
                "id" : "id1",
                "lastName" : "Kotha"
            }, 
            {
                "firstName" : "Sathish",
                "id" : "id2",
                "lastName" : "Kotha"
            } 
        ];

I did this but encountered the following exception:

com.fasterxml.jackson.databind.JsonMappingException: No suitable constructor found for type [simple type, class ca.ted.TestController$Person]: can not instantiate from JSON object (need to add/enable type information?)

Turns out this was because Person was an inner class in my Controller. I moved it out to its own file, ca.ted.Person and all was well.

Hope this helps!

answered Aug 29, 2014 at 20:34

Edward Smith

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3 Comments

StevieJ81 Over a year ago

Actually I seem to have hit a new problem. The JSON is parsed successfully by the controller, but it always returns an error saying "not acceptable". The logs report: "Could not find acceptable representation"

StevieJ81 Over a year ago

Got it. This was because the example used the .htm extension which is apparently confusing my dispatchservlet. See: stick2code.blogspot.com.au/2014/03/…

Edward Smith Over a year ago

Ah! Nice catch. Glad I was able to help!

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