查询文档之间的连接

Question

我想在 CouchDb 中创建一个视图，其中包含来自多个链接文档的一些字段。我的文档是这样的：

/*Products:*/
{
    "_id": "Products:ABC",
    "doctype": "Products",
    "productCode": "ABC",
    "description": "The best product you ever seen",
    "category_id": "Categories:1",
    "brand_id": "Brands:52"
},
{
    "_id": "Products:DEF",
    "doctype": "Products",
    "productCode": "DEF",
    "description": "DEFinitely a good product",
    "category_id": "Categories:2",
    "brand_id": "Brands:53"
},

/*Categories*/
{
    "_id": "Categories:1",
    "categoryID": "1",
    "description": "Awesome products"
},
{
    "_id": "Categories:2",
    "categoryID": "2",
    "description": "Wonderful supplies"
},

/*Brands*/
{
    "_id": "Brands:52",
    "brandID": "52",
    "description": "Best Items"
},
{
    "_id": "Brands:53",
    "brandID": "53",
    "description": "Great Gadgets"
},

我想要这样的结果：

/*View results: */
{
    "id": "Products:ABC",
    "key": "Products:ABC",
    "value": {
        "productCode": "ABC",
        "description": "The best product you ever seen",
        "category": {
            "categoryID": "1",
            "description": "Awesome products"
        },
        "brand": {
            "brandID": "52",
            "description": "Best Items"
        }
    }
},
{
    "id": "Products:DEF",
    "key": "Products:DEF",
    "value": {
        "productCode": "DEF",
        "description": "DEFinitely a good product",
        "category": {
            "categoryID": "2",
            "description": "Wonderful supplies"
        },
        "brand": {
            "brandID": "53",
            "description": "Great Gadgets"
        }
    }
},

目标是获得一个连接三个文档的结果。可以吗？

正如你想象的那样，我来自 SQL 世界，所以也许我在设计数据库时大错特错，所以欢迎任何有关如何更改文档结构的建议！

提前致谢！

弗朗切斯科

Answer 1

有两种方法可以做到这一点：

使用 query() API 和 linked documents（在页面中搜索 "linked documents"）
使用 relational-pouch 插件

relational-pouch 插件的优势在于，在底层，它比链接文档更快，因为它不依赖于建立 map/reduce 索引。链接文档的优点是它是 CouchDB 中解决这个问题的更传统的方法，而且它不依赖于额外的插件。选择你喜欢的任何一个。 :)

编辑： 重新阅读您的问题，我发现您想将 3 种不同的文档类型合并在一起。目前这对链接文档是不可能的（你只能 "join" 两种类型），而关系袋是可能的。所以我想这使决定变得容易。 :)

查询文档之间的连接

Query with join between documents

javascript

couchdb

pouchdb