grails - 保存新记录时动态发现关系的更好方法？ (对方失败)

Question

鉴于这种关系:

class A {
    String name
    static hasMany = [b:B]
}
class B {
    String name
    static belongsTo = [a:A]
}

我有一条要保存的记录 b。我已经通过工作 Grails 反射(在下面的代码示例中省略)发现它需要是 B 类的一个实例。除此之外，记录b只知道:

它有一个关系“a”

关系“a”的键

由于是动态案例，我们不知道但必须发现:

关系“a”是 的一个实例A类 (所以我们可以调用 A .find(a's key))

关系的“另一面”——A 类的观点——是关系“ b ”(所以我们可以调用 .addToB (b))

那么如何将 b 保存到数据库中呢？这是我的做法:

class AssocTests extends GrailsUnitTestCase {
    protected void setUp() {
        super.setUp()
        // I don't know this part, but it's in the DB
        def a = new A(name:"al")
        a.save()
    }

    void testAssociation() {
        // I want to create a new B such that name="bob"
        // I also had to discover "class B" using (working) Grails reflection
        // but omitted it for this example.
        def b = new B(name:"bob")
        // ... and the relation is as "given" below
        def given = [a:[name:"al"]]
        // So I need to call A.find([name:"al"]).addToB(b).  But "A" and
        // "addToB" are unknown so need to be found via reflection
        def gdc = new DefaultGrailsDomainClass(B)
        given.each { give ->
            def prop = gdc.getPropertyByName(give.key)
            if (prop.isAssociation() && !prop.isOwningSide()) {
                println "I want to use otherSide, but it's ${prop.otherSide}"
                def os = reallyGetOtherSide(B, give)
                def object = os.parent.find(
                        os.parent.newInstance(give.value))
                object."${os.method}"(b)
            }       
        }       
        def bFound = B.findByName("bob")
        assertEquals "al", bFound.a.name
    }

    def reallyGetOtherSide(clazz, relation) {
        def parent=clazz.belongsTo[relation.key] 
        def addTo=parent.hasMany.find { (clazz == it.value) }.key
        [parent:parent, method:"addTo${addTo.capitalize()}"]
    }
}

...不幸的是， otherSide 返回 null。这不可能是最好的方法，不是吗？

Answer 1

如果我理解正确，您可以引用这些文档 here .您可以尝试以下方法:

  `new A(name:"Gatwick")
         .addToB(new B(name:"BA3430"))
         .addToB(new B(name:"EZ0938"))
         .save()`