grails - grails 中 find() 和 findWhere 的区别

Question

我使用 find :

 find("from domain d where d.id=? AND d.name=?",[params.id, params.name])

这给了我第一个匹配结果。
现在我看到有 findWhere() 用于:

  Book.findWhere(author: params.author, title: params.title)

还返回第一个匹配结果集。
什么是基本区别以及何时使用。

先感谢您。

Answer 1

对，所以我创建了一个测试应用程序，创建了一个测试域类:

package test

class Book {
    String title
    String author

    static constraints = {
    }
}

在 Bootstrap 中添加了一些虚拟数据:

import test.*

class BootStrap {

    def init = { servletContext ->
        new Book( title:'Book 1', author:'Tim' ).save()
        new Book( title:'Book 2', author:'Alice' ).save()
        new Book( title:'Book 3', author:'Bob' ).save()
    }
    def destroy = {
    }
}

和一个测试 Controller :

package test

import grails.converters.JSON

class BookController {
    def test1() {
        Book b = Book.find( "from Book as b where b.author = ? and b.title = ?", [ 'Tim', 'Book 1' ] ) 
        render b as JSON
    }
    def test2() {
        Book b = Book.findWhere( author:'Tim', title:'Book 1' ) 
        render b as JSON
    }
    def test3() {
        Book b = Book.findByAuthorAndTitle( 'Tim', 'Book 1' ) 
        render b as JSON
    }
}

然后，通过添加打开休眠日志记录

trace 'org.hibernate.type'
debug 'org.hibernate.SQL'

到 Config 的 log4j 部分，并且:

logSql = true

到 DataSource.groovy 的 dataSource 部分。

然后，运行所有 3 个 Controller 方法。
find 执行:

select book0_.id as id0_,
       book0_.version as version0_,
       book0_.author as author0_,
       book0_.title as title0_
from book book0_
where book0_.author=? and book0_.title=? limit ?

findWhere 执行:

select this_.id as id0_0_,
       this_.version as version0_0_,
       this_.author as author0_0_,
       this_.title as title0_0_
from book this_
where (this_.author=? and this_.title=?) limit ?

findByAuthorAndTitle 给了我们:

select this_.id as id0_0_,
       this_.version as version0_0_,
       this_.author as author0_0_,
       this_.title as title0_0_
from book this_
where this_.author=? and this_.title=? limit ?

正如你所看到的，在这个简单的例子中，它们只是表达同一件事的 3 种方式