CouchDB文档更新处理程序（就地更新） [英] CouchDB Document Update Handlers (in-place updates)

问题描述

http://wiki.apache.org/couchdb/Document_Update_Handlers

CouchDB（0.10及更高版本）现在支持就地更新。我无法理解其工作原理。我尝试使用提供的示例，但无法正常工作。

CouchDB ( 0.10 and above ) supports in-place updates now. I'm having trouble understanding how it works. I tried to use the example provided but I couldn't get it to work.

有人可以提供一些示例和uri用于访问就地更新。

Can someone provide some examples and uris used to access the in-place updates.

谢谢

推荐答案

示例函数 in- place 与其他
数据库中的就地更新不同。 CouchDB仍然使用仅追加的体系结构。文档更新
处理程序仍会创建新的文档修订版，等等。

The example function in-place is not the same as "in-place" updates in other databases. CouchDB still uses an append-only architecture; document update handlers still create a new doc revision, etc.

不过，更新处理程序非常方便，值得学习。

Still, update handlers are quite convenient and worth learning.

假设您有一个带有累加器的文档。您
希望仅通过一个HTTP查询在文档中累积一个整数，并使用 amount 参数指定
增量。请考虑以下命令：

Suppose you have a document with an accumulator. You want to accumulate an integer in a document with just one HTTP query, specifying the increment amount using an amount parameter. Consider the following commands:

curl -X PUT http://localhost:5984/db
# Returns {"ok":true}

curl -H "Content-Type:application/json" -X POST http://localhost:5984/db/_bulk_docs -d @-
{"docs":
  [
    {"_id": "my_doc", "number": 23},
    {"_id": "_design/app",
      "updates": {
        "accumulate": "function (doc, req) {
                         var inc_amount = parseInt(req.query.amount);
                         doc.number = doc.number + inc_amount;
                         return [doc, \"I incremented \" +
                                      doc._id + \" by \" +
                                      inc_amount];
                       }"
      }
    }
  ]
}
# Returns [{"id":"my_doc","rev":"1-8c9c19a45a7e2dac735005bbe301eb15"},
#          {"id":"_design/app","rev":"1-83ec85978d1ed32ee741ce767c83d06e"}]

（请记住t o在POST中的JSON对象后按文件结尾^ D。）

(Remember to press end-of-file, ^D, after the JSON object in the POST.)

下一步，确认要累积的文档（ my_doc ）存在：

Next confirm the document for accumulation (my_doc) exists:

curl http://localhost:5984/db/my_doc
# Returns {"_id":"my_doc","_rev":"1-8c9c19a45a7e2dac735005bbe301eb15",
#          "number":23}

现在，您可以使用 amount 参数调用累积更新处理程序b $ b更新该字段。

Now you can call the accumulate update handler with an amount parameter to update the field.

curl -X PUT \
 http://localhost:5984/db/_design/app/_update/accumulate/my_doc?amount=15
# Returns: I incremented my_doc by 15

curl http://localhost:5984/db/my_doc
# Returns {"_id":"my_doc","_rev":"2-<whatever>",
#          "number":38}

请注意，新的数字值为38，即23 + 15。

Notice that the new number value is 38, the value of 23 + 15.

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