Post a JSON Array into Spring Boot RestController

Question

I am posting something like this:

{
  "stuff": [
    {
      "thingId": 1,
      "thingNumber": "abc",
      "countryCode": "ZA"
    },
    {
      "thingId": 2,
      "thingNumber": "xyz",
      "countryCode": "US"
    }
  ]
}

I can retrieve the data in the controller as follows:

@RequestMapping(value = "/stuffs", method = RequestMethod.POST)
public String invoices(@RequestBody Map<String, List <Stuff>> stuffs) {

    return "Hooray";
}

What I'd really like to do is to only pass in a List of Stuff into the controller; ie:

@RequestMapping(value = "/stuffs", method = RequestMethod.POST)
public String invoices(@RequestBody List <Stuff> stuffs) {

    return "I'm sad that this won't work.";
}

However, Jackson does not like this. The error I get is the following:

Could not read JSON document: Can not deserialize instance of java.util.ArrayList out of START_OBJECT token\n at [Source: java.io.PushbackInputStream@2a30a2f4; line: 1, column: 1]; nested exception is com.fasterxml.jackson.databind.JsonMappingException: Can not deserialize instance of java.util.ArrayList out of START_OBJECT token\n at [Source: java.io.PushbackInputStream@2a30a2f4; line: 1, column: 1]

I cannot send in the following (since it's not valid JSON):

    {
      [
        {
          "thingId": 1,
          "thingNumber": "abc",
          "countryCode": "ZA"
        },
        {
          "thingId": 2,
          "thingNumber": "xyz",
          "countryCode": "US"
        }
      ]
    }

I am sure that this is something simple, but I cannot distil an answer from my StackOverflow and Google searches.

Any help would be appreciated! :)

Amer Qarabsa · Accepted Answer · 2017-05-16 09:43:50Z

10

you only need to send this without the curly brackets

   [
    {
      "thingId": 1,
      "thingNumber": "abc",
      "countryCode": "ZA"
    },
    {
      "thingId": 2,
      "thingNumber": "xyz",
      "countryCode": "US"
    }
  ]

In your controller when you tell Jackson that it should be parsing a list it should be a list not an object containing a list

answered May 16, 2017 at 9:43

Amer Qarabsa

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1 Comment

orrymr Over a year ago

Yes! I'll choose this as accepted answer as soon as time limitation passes. You have saved me from some immense frustration!

S. Pan · Accepted Answer · 2017-11-17 07:46:24Z

9

Note that if you're trying to get an array of JSON without a Java Class (the Class being "Stuff" in the OP's question) you will need to set up the Spring Boot Controller like this:

@RequestMapping(value = "/stuffs", method = RequestMethod.POST)
public String invoices(@RequestBody Map<String, Object> [] stuffs) {

    return "Hooray";
}

answered Nov 17, 2017 at 7:46

S. Pan

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