Grails domain constructor with JSON parameter did not work

Question

I have such controller in my grails project:

def submit() {
    def json = request.JSON
    Share share = new Share(json)
    share.save(flush: true,  failOnError: true)
}

Class Share looks like this:

class Share {

    String timestamp
    String deviceName
    String originMessage

Share(JSONObject originalMessage) {
    println "Run JSON constructor"
    println "$originalMessage"

    originMessage = originalMessage.toString()
    timestamp = originalMessage.timestamp
    deviceName = originalMessage.device
}

It recives JSON request and try to persist in data base.

I get such error in my console on failOnError:

Field error in object 'com.entity.Share' on field 'deviceName': rejected value [null];
Field error in object 'com.entity.Share' on field 'originMessage': rejected value [null]; codes

A lot of dancing around find one possible way: in controller convert JSON to string and pass it in constructor where parameter would be type String and then parse it back in JSON using JSON converter. But why I can not pass JSON Object as parameter correctly. What happens?

Remove your constructor and try again. Grails already have this kind of constructor for domain classes. — user800014
Yes, I know it, but I dislike mapping style of constructor. Nevertheless why I see such strange behavier? — sphinks

Dónal Dónal · Accepted Answer · 2014-01-14T10:58:06

I don't see much point in declaring this constructor because domain classes already have an implicit constructor that takes a Map argument. You could call this constructor with the JSONObject because this class implements Map, e.g.

class Share {

    String timestamp
    String deviceName
    String originMessage
}

def json = request.JSON
Share share = new Share(json)

The reason for these errors

Field error in object 'com.entity.Share' on field 'deviceName': rejected value [null];
Field error in object 'com.entity.Share' on field 'originMessage': rejected value [null]; codes

is that your JSONObject instance does not have non-null properties named deviceName or originMessage.

Either you need to figure out why these properties are missing, or allow these properties to be null by adding the following constraints to the domain class

class Share {

    String timestamp
    String deviceName
    String originMessage

    static constraints = {
        deviceName nullable: true
        originMessage nullable: true 
    }
}

Grails domain constructor with JSON parameter did not work

1 Answers