a list of checkboxes

Question

I have two domain classes

class Contract {
    String number
    static hasMany = [statements:Statement]
}

class Statement {
    String code
    static hasMany = [contracts:Contract]
}

I would like to show all statements available in my gsp with a checkbox next to each, allowing the user to choose which statements are applicable to the contract. So something like:

[ ] Statement Code 1
[ ] Statement Code 2
[ ] Statement Code 3

I started off with this:

<g:each in="${Statement.list()}" var="statement" status="i">
    <g:checkBox name="statements[${i}].id" value="${statement.id}" checked="${contractInstance.statements.contains(statement.id)}" />
    <label for="statements[${i}]">${statement.code}</label>
</g:each>

But i just cannot get a list of checked statements to the controller (there are null elements in the list, there are repeated statements...).

Any idea how to achieve this?

Answer 1

This is possible, but it does require a bit of a hack. First off, every checkbox must have the same name, "statements":

<g:each in="${org.example.Statement.list(sort: 'id', order: 'asc')}" var="statement" status="i">
    <g:checkBox name="statements" value="${statement.id}" checked="${contract.statements.contains(statement)}" />
    <label for="statements">${statement.content}</label>
</g:each>

Second, in the controller you have to remove the "_statements" property before binding:

def contract = Contract.get(params.id)
params.remove "_statements"
bindData contract, params
contract.save(failOnError: true)

The check box support hasn't been designed for this use case, hence the need for a hack. The multi-select list box is the one typically used for this type of scenario.

Answer 2

I personally prefer to get the list of Id's in this case.

<g:each var="book" in="${books}">
    <g:checkBox name="bookIds" value="${book.id}" ...
</g:each>

Command Object:

class BookCommand {
    List<Serializable> bookIds
}

In controller action:

BookCommand bc ->
    author.books = Book.getAll(bc.bookIds)