具有输入键的CouchDB中的Distinct

Question

给定的文档，如：

[
{"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和类型键并返回不同的行，例如传入"cat1"和"type1"的键并返回["line1", "line2"]，或者传入"cat2"和"type1"并返回["line2", "line3"]

如果我是而不是传入密钥，那就更容易了：

地图

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

降低

function(keys, values) {
  return null;
}

我正在使用group：没错，但在传递密钥时，我对如何处理这个问题感到困惑。

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类型键并返回不同的行，即传入"cat1"one_answers"type1"的键并返回["line1"、"line2"]或传入"cat2"one_answers"type 1"并返回["line2"、"line3"]

您可以通过使用正确的参数查询以下map和reduce来获得：

地图

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

降低

_count

查询

对于"cat1"one_answers"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"one_answers"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}
]}