(Quick Reference)
select
Purpose
Generates HTML selects.
Examples
// create a select from a range
<g:select name="user.age" from="${18..65}" value="${age}"
noSelection="['':'-Choose your age-']"/>// use a no selection with a nullable Object property (use 'null' as key)
<g:select id="type" name='type.id' value="${person?.type?.id}"
noSelection="${['null':'Select One...']}"
from='${PersonType.list()}'
optionKey="id" optionValue="name"></g:select>// create select from a list of companies
// note the 'optionKey' is set to the id of each company element
<g:select name="user.company.id"
from="${Company.list()}"
value="${user?.company.id}"
optionKey="id" />// create multiple select
<g:select name="cars"
from="${Car.list()}"
value="${person?.cars*.id}"
optionKey="id"
multiple="true" />// create select with internationalized labels (this is
// useful for small static lists and the inList constraint).
// expected properties in messages.properties:
// book.category.M=Mystery
// book.category.T=Thriller
// book.category.F=Fantasy
<g:select name="book.category" from="${['M', 'T', 'F']}"
valueMessagePrefix="book.category" />Example as a method call in GSP only:
${select(from:aList,value:aValue)}Description
Attributes
name (required) - The name of the select elementfrom (required) - The list or range to select fromvalue (optional) - The current selected value that evaluates equals() to true for one of the elements in the from list.optionKey (optional) - By default value attribute of each <option> element will be the result of a toString() call on each element. Setting this allows the value to be a bean property of each element in the list.optionValue (optional) - By default the body of each <option> element will be the result of a toString() call on each element in the from attribute list. Setting this allows the value to be a bean property of each element in the list.keys (optional) - A list of values to be used for the value attribute of each option element.noSelection (optional) - A single-entry Map detailing the key and value to use for the "no selection made" choice in the select box. If there is no current selection this will be shown as it is first in the list, and if submitted with this selected, the key that you provide will be submitted. Typically this will be blank - but you can also use 'null' in the case that you're passing the ID of an objectvalueMessagePrefix (Optional) - By default the value of the option element will be the result of a toString() call on each element in the from attribute list. Setting this allows the value to be resolved from the i18n messages. The valueMessagePrefix will be suffixed with a dot ('.') and then the value attribute of the option to resolve the message. If the message could not be resolved, the value is presented.multiple (optional) - Set to true to generate a multi-select listbox rather than a dropdown list.
The
optionKey and
optionValue attribute of the
<g:select> tag deserve special mention as these let you control what is displayed to the user within the resulting
<select> tag and also the value which is submitted in a form submission. The default behaviour is to call
toString() on each element in the
from attribute, but for example if you had a list of
Book domain classes this may not be useful behaviour.
As an example the following
<g:select> uses the
optionKey attribute to resolve the
id property of each
Book as the value of the
value attribute in each
<option> tag. It also uses the
optionValue attribute of
<g:select> to display the
title property of each
Book to the user:
<g:select optionKey="id" optionValue="title"
name="book.title" from="${bookList}" />If you require even more control over how each
<option> element is presented to the user you can use a closure to apply a transformation within the
optionValue attribute. As an example, the following code transforms each
Book title to upper case:
<g:select optionKey="id" optionValue="${{it.title?.toUpperCase()}}"
name="book.title" from="${bookList}" />If you specify an
optionKey then be aware that you should use that property in the
value attribute in order to pre-select an item in the drop down list. For example, let's say we have a
favoriteBook that we want to pre-select in a list of books:
<g:select optionKey="id" value="${favoriteBook.id}"
name="book" from="${bookList}" />In this case,
value should contain the ID of
favouriteBook rather than the book object itself because
optionKey is set to the
id property.
Source
