梵蒂冈之花
是否可以找到与给定密钥相关的所有产品？当您存储一片键时，如果不检索所有实体，则不可能做到这一点。但是，您可以创建一种新类型（RelatedProducts），用于存储相关产品（使用产品作为父键）。示例（未经测试）type Product struct { Name string}type RelatedProducts struct { // We store the the OriginalProduct as parent, so it is not needed as a property Related *datastore.Key}// Create a new relationfunc newRelation(c appengine.Context, productKey *datastore.Key, relatedProduct *datastore.Key) { key := datastore.NewIncompleteKey(c, "RelatedProducts", productKey) datastore.Put(c, key, &RelatedProduct{Related: relatedProduct})}// Get all related productsfunc getAllRelatedProducts(c appengine.Context, productKey *datastore.Key) []*datastore.Key{ var relatedProducts []RelatedProducts // Query the relations query := datastore.NewQuery("RelatedProducts").Ancestor(productKey) query.GetAll(c, &relatedProducts) // Loop over relatedProducts and append the data to keys var keys []*datastore.Key for i := range relatedProducts { keys = append(keys, relatedProducts[i].Related) } return keys}