Question

给出如下文件：

[
{"id":1, "category": "cat1", "type": "type1", "line": "line1"},
{"id":2, "category": "cat1", "type": "type1", "line": "line1"},
{"id":3, "category": "cat1", "type": "type2", "line": "line1"},
{"id":4, "category": "cat1", "type": "type1", "line": "line2"},
{"id":5, "category": "cat2", "type": "type1", "line": "line2"},
{"id":6, "category": "cat2", "type": "type1", "line": "line3"}
]

我希望能够传入类别并输入键并返回不同的行，例如传递"cat1"和"type1"的密钥并返回["line1", "line2"]或传入"cat2"和"type1"并返回["line2", "line3"]

如果我不传递密钥，则更容易：

地图

function(doc) {
    emit([doc.line]);
}

减少

function(keys, values) {
  return null;
}

我正在使用group：true，但是在传入密钥时难以理解如何处理它。

PS，使用node和nano所以查询看起来类似于：

db.view('catalog', 'lines', {key: ['cat1', 'type1'], group: true}, function (err, body) {
...
});

Answer 1

我希望能够传入类别和键入键并返回不同的行，即传入“cat1”和“type1”的键并返回[“line1”，“line2”]或传入“ cat2“和”type1“并返回[”line2“，”line3“]

您可以通过使用正确的参数查询以下map和reduce来获取该信息：

<强>地图

function(o) {
  emit([o.category, o.type, o.line]);
}

<强>减少

_count

<强>查询

对于“cat1”和“type1”：

/mydb/_design/mydesign/myview?group=true&startkey=["cat1","type1"]&endkey=["cat1","type1",{}]

{"rows":[
{"key":["cat1","type1","line1"],"value":2},
{"key":["cat1","type1","line2"],"value":1}
]}

对于“cat2”和“type1”：

/mydb/_design/mydesign/myview?group=true&startkey=["cat2","type1"]&endkey=["cat2","type1",{}]

{"rows":[
{"key":["cat2","type1","line2"],"value":1},
{"key":["cat2","type1","line3"],"value":1}
]}

使用输入键在CouchDB中有所区别

1 个答案: