grails find objects by many parameters

I have rather big form where a user can choose any number of parameters (from 1 to 10).

Example:

1. Cities - NYC, LA ; age - 18
2. Cities - null (nothing was chosen) ; age - 23, 57

How should I implement a find method at the GORM level (bad way - method that composes query string, add params if not null, etc)?

Then I should search in my database for app开发者_高级运维ropriate objects. Another limitation - should use executeQuery?

**[EDITED]*** I remembered that i didn`t post my own answer. There it is:

    def resultList = Organization.createCriteria().list(max: params.max, offset: params.offset) {
        and {
            if (params.chosenNomenc != null) {
                nomenclatures {
                    ilike("title", params.chosenNomenc)//for string
                }
            }
            if (params.chosenCountries != null) {
                countries {
                    'in'("title", params.chosenCountries)//for list
                }
            }              
            cache true
            order("id", "asc")
        }
    }
    println("resultList:" + resultList)
    [organizationList: resultList, total: resultList.totalCount, params: params]
}

Regards, Dmitry.

Using Criteria in the controller is the best way.

    def locProps = Location.metaClass.properties*.name
    def locs = Location.withCriteria {
        and {
            params.each { field, value ->
                if (locProps.grep(field) && value) {

                    // more checks here

Use the Criteria API and in it's closure you can use conditional statements (if/else) to build it based on the presence of params.

Assuming your <select> tags are named ages and cities and you have a Person domain with String properties age and city:

Person.withCriteria {
  if (params.list('ages')) { // inList('fieldName', null) causes an error
    inList 'age', params.list('ages')
  }
  if (params.list('cities')) {
    inList 'city', params.list('cities')
  }
}

I suggest you to user createCriteria or withCriteria only.
Lets take an example:
If the parameters to the action are as u had given:
1) Cities - NYC, LA ; age - 18
2)Cities - null(nothing was chosen) ; age - 23, 57

And suppose your domain class is User then:

def result = User.withCriteria (max: params.max){
   if (params.Cities)
        eq('city', params.Cities)
   if (params.age)
        eq('age', params.age)
}

It will return list of the matching objects of domain class User.
For more details, Please take a look at createCriteria or withCriteria in Grails documentation.