ID字段上的Grails搜索会引发错误

Question

I have a search page where the user should be able to search authors based on their id (GORM generated id, not a property in my domain class) or their name. The search page works fine when I search on the author's name but when trying to search on their id, I get the error below.

Message:

java.lang.String cannot be cast to java.lang.Long

Please let me know how I can fix this.

Here is my search method in the controller:

def search(Integer max) {
    params.max = Math.min(max ?: 10, 100)

    def authorList = Author.createCriteria().listDistinct () {
        if ( params.id ) {
            eq("id", "%${params.id}%")
        }
        if ( params.name ) {
            ilike("name", "%${params.name}%")
        }


    respond authorList, model:[authorInstanceCount: Author.count()]
}

Answer 1

Replace this:

eq("id", "%${params.id}%")

with

eq("id", params.long('id'))

params.long('id') tries to safely convert the parameter to a Long , ie it will return null if the conversion cannot be performed rather than throwing an exception.

Answer 2

The exception you get is quite informative. You're trying to pass java.lang.String in place where java.lang.Long is required. Pass params.id without converting it to string:

eq("id", params.id) // if params.id is java.lang.Long
// or
eq("id", params.id.toLong()) // if params.id is java.lang.String

You've also missed closing curly bracket after closure of listDistinct() method (it might be a mistake during copy-pasting).