16 březen 2013
The params object added to groovlets and templates has one
very enpleasant feature that it either contains values of type String or String[] depending on how many parameters were submitted. In
Gaelyk 2.0 is now handling parameters much easier.
Prior Gaelyk 2.0 following unpleasant situation may occur:
Problems with params prior Gaelyk 2.0
// query = ?tag=one&tag=two
params.tag == ['one','two'] as String[]
// this is ok
params.tag.collect { it } == ['one', 'two']
// query = ?tag=one
params.tag == 'one'
// oops, String.each iterates over characters
params.tag.collect { it } == ['o', 'n', 'e']
// query = ?limit=100
params.limit == '100'
params.limit as int == 100
// query = ?limit=100&limit=200
params.limit == ['100', '200'] as String[]
try {
params.limit as int
assert false
} catch(ClassCastException e) {
// cannot cast String[] to int
assert true
}
These casts are now safe in Gaelyk 2.0.
Safe parameters handling in Gaelyk 2.0
// query = ?tag=one&tag=two
params.tag == ['one','two'] as String[]
// this is ok
params.tag.collect { it } == ['one', 'two']
// query = ?tag=one
params.tag == 'one'
// oops, String.each iterates over characters
params.tag.collect { it } == ['o', 'n', 'e']
// use as String[] to ensure having String array
(params.tag as String[]).collect { it } == ['one']
// query = ?limit=100
params.limit == '100'
params.limit as int == 100
// query = ?limit=100&limit=200
params.limit == ['100', '200'] as String[]
// first value is taken on cast to single value (not array or collection)
params.limit as int == 100
Simply said use as String[] on values from params whenever you expect multiple values and as <type supported by String.asType() or String> if you expect single value.