CouchDB“加入"两个文件 [英] CouchDB "Join" two documents

问题描述

我有两个看起来像这样的文件:

I have two documents that looks a bit like so:

Doc
{
  _id: AAA,
  creator_id: ...,
  data: ...
}

DataKey
{
  _id: ...,
  credits_left: 500,
  times_used: 0,
  data_id: AAA
}

我想做的是创建一个视图，该视图允许我传递DataKey id(key = DataKey _id)并同时获取DataKey和文档的信息.

What I want to do is create a view which would allow me to pass the DataKey id (key=DataKey _id) and get both the information of the DataKey and the Doc.

我的尝试

我首先尝试将DataKey嵌入到Doc中，并使用如下所示的map函数:

I first tried embedding the DataKey inside the Doc and used a map function like so:

function (doc)
{
  if (doc.type == "Doc")
  {
    var ids = [];
    for (var i in doc.keys)
      ids.push(doc.keys[i]._id);

    emit(ids, doc);
  }
}

但是我遇到两个问题:

1. 每个可以有多个DataKey Doc，所以使用startkey = [idhere ...] 并且endkey = [idhere ...，{}]没有 工作(仅在密钥发生时工作 成为数组中的第一个).
2. 所有数据密钥都必须是唯一的，我宁愿不要制作像{_id = datakey}这样的单独文档来保留密钥.

1. There can be multiple DataKey's per Doc so using startkey=[idhere...] and endkey=[idhere..., {}] didn't work (only worked if the key happend to be the first one in the array).
2. All the data keys need to be unique, and I would prefer not making a seperate document like {_id = datakey} to reserve the key.

有人知道我如何做到这一点吗?让我知道是否有任何不清楚的地方.

Does anyone have ideas how I can accomplish this? Let me know if anything is unclear.

-----编辑-----

我忘了提到我的应用程序中我不知道文档ID是什么，因此我需要能够搜索DataKey的ID.

I forgot to mention that in my application I do not know what the Doc ID is, so I need to be able to search on the DataKey's ID.

推荐答案

我认为您想要的是

function (doc)
{
  if (doc.type == "Doc")
  {
    emit([doc._id, 0], doc);
  }

  if(doc.type == "DataKey")
  {
    emit([doc.data_id, 1], doc);
  }
}

现在，使用key=["AAA"]查询视图，您将看到所有文档的列表.第一个将是真实的"Doc"文档.其余所有将是引用第一个文档的"DataKey"文档.

Now, query the view with key=["AAA"] and you will see a list of all docs. The first one will be the real "Doc" document. All the rest will be "DataKey" documents which reference the first doc.

这是一种常见的技术，称为 CouchDB视图排序规则.

This is a common technique, called CouchDB view collation.

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