Question

I am running a grails application and I am receiving the weirdest error I’ve probably ever encountered. One “field” in a model got data that just disappears for no reason.

I have two Model or a Domain class in my project with the following set up:

class Insertion {

String title
Date insertDate

static hasMany = Dataholder

  static constraints = {
    title(unique: true)
  }
}



class Dataholder {

    String product
    int somenumber
    int somenumber2
    int somenumber3
    Date startDate
    Date endDate
    List<String> somedatalist
    Insertion insertions

    static belongsTo = Insertion

    static constraints = {
    }
}

The “insertion” class is representing every time a user might input a bunch of dataholders. The dataholder represents all the data for that specific product. Important to know is that the data that disappears is contained in the Dataholder model and the ONLY data that disappears is the somedatalist.

This is the magic which is completely confusing, when I insert the data and saves it. It all goes well:

if (!errors) {

            dataholderValidator.each {
                it.insertion = insertion
                it.save()
            }

        def results = Dataholder.findAllByInsertion(insertion)

I do some validating and apply data to every Dataholder and then if everything goes well, if(!errors) I add the insertion to each object. After that is done I save each objec, saving the data to the database. You may think it’s going wrong here but just wait and be amazed.

After saving I get all the Dataholders from the database (since I want to be sure that the data was saved before printing it out to the user) by using the insertion. This is where the strange part begin, what I get back is the correct data:

results.each {
                it.somedatalist.each { it2 ->
                    if(!weekdays.contains(it2))
                        weekdays.add(it2)
                }
            }

Populate an array with all the unique items from the datalist. Then printing it out to the view and voila:

Now, we just wait for the users confirm of all the data in the view and when he or she is clicking on a confirm button the insertion title is sent with post to function which would retrieve the data and to my surprise the somedatalist is null.

This is the functionality that retrieves the data:

    def result = Insertion.findByTitle(insertionTitle)

    def results = Dataholder.findAllByInsertions(result)

When putting a breaking point after results I can for sure confirm that every Dataholder contains the correct the right data except that somedatalist which is equal to null.

I’ve tried to get the data above by using the Insertion Title instead of just using the object and it works well. I can’t understand why the data is populated in the database in one second and how something can just disappear?

Test:

void testSaveDataholder() {
        Insertions insertion = new Insertion(title: 'adadad', insertDate: new Date())
        insertion.save()
        assert Insertion.all.size() == 1
        Dataholder ed = new Dataholder(product:  'abc123', somenumber:  123, somenumber2: 13, startDate: new Date(), endDate: new Date(), somedatalist: ['TI'], insertions:  insertion)
        ed.save()
        assert Dataholder.all.size() == 1
        assert Dataholder.all.first().somedatalist.size() == 1
        assert Dataholder.all.first().insertions.title == 'adadad'
        assert Insertion.findAllByTitle('adadad').size() == 1
        assert Dataholder.findAllByInsertions(Insertion.all.first()).size() == 1
    }

This test all returns true, I am using Grails 2.1.

EDIT: I am using the in-memory database with “update” as configuration. So I can’t really view the data. But it should be there.

Please help me with your sage advice and better wisdom.

Answer 1

It just has come to my mind. Persisting a collection of objects into single column breaks the 1st normal form, so it is not the correct way to do it. I have immediately googled an issue in JIRA:

http://jira.grails.org/browse/GRAILS-1023

The correct way is to create a new domain class with single String attibute and use standard one-to-many relation.