Question

我正在尝试向Mongo的MongoCollection和FindIterable类添加一些Groovy-er方法。

如果我通过ExpandoMetaClass添加方法，则效果很好：

// add convenience methods to MongoCollection, and FindIterable to make it more groovy friendly.

// Usage: `collection.find(partnerId: 2).each { ... }`
//    or: `collection.find([partnerId: 2]).each { ... }`
MongoCollection.metaClass.find << { Map filter ->
    return find((Bson) new Document(filter))
}

// Usage: `collection.find().projection(_id: 0, Rid: 1, DeliveryPartnerId: 1).each { ... }`
FindIterable.metaClass.projection << { Map fields ->
    return projection((Bson) new Document(fields))
}

但是，当我尝试通过Expansion Module添加方法时：

/**
 * Adds Groovy Map friendly extension methods to MongoCollection and FindIterable.
 */
class GroovyMongoExtensions {

    /**
     * Makes it easy to call the find method on a MongoCollection with a Map, or Map parameters.
     * Example:
     * <pre>collection.find(group: 10).each { ... }</pre>
     * or:
     * <pre>collection.find([group: 10]).each { ... }</pre>
     */
    static FindIterable find(MongoCollection self, Map filter) {
        return self.find((Bson) new Document(filter))
    }

    /**
     * Makes it easy to call the projection method on a FindIterable with a Map, or Map parameters.
     * Example:
     * <pre>collection.find().projection(myId: 1, name: 1).each { ... }</pre>
     */
    static FindIterable projection(FindIterable self, Map fields) {
        return self.projection((Bson) new Document(fields))
    }
}

我收到此错误：

Exception in thread "main" groovy.lang.GroovyRuntimeException: Ambiguous method overloading for method com.mongodb.client.internal.MongoCollectionImpl#find.
Cannot resolve which method to invoke for [class org.bson.Document] due to overlapping prototypes between:
        [interface org.bson.conversions.Bson]
        [interface java.util.Map]

我确实从ExpandoMetaClass方法中得到了错误，但是在这种情况下，将显式强制转换添加到(Bson)即可解决此问题。

Groovy扩展模块与ExpandoMetaClass的添加

0 个答案: