简单的 reduce 函数不起作用，我在 couchDB 中的 reduce 函数代码有什么问题？

Question

我是 couchDB 的新手。我从简单的 map/reduce 开始。我不知道为什么我无法收到我附加的代码段的正确值。提前致谢！！！

我的映射代码如下：

function(doc){ 
if(doc.release.formats.format.descriptions.description == 'Album'){
doc.release.artists.artist.forEach(function(i){emit(i.name,doc.release.title)})
}
}

我生成的地图值键："Trevor loveys" 值："Era"

我的reduce代码

 function(keys,values,rereduce)
{
 for(var i=0; i<keys.length();i++)
{
 if(keys[i] == "Trevor Loveys")
 {
  return values;
}
}

一旦我减少了，我得到的答案就像

键："Trevor loveys" 值：空

更新。下面提供了我的 json 数据示例：

{
"release": {
    "genres": {
        "genre": "Electronic"
    },
    "status": "Accepted",
    "videos": {
        "video": [
            {
                "title": "Reflections- 2nd Nature",
                "duration": 436,
                "description": "Reflections- 2nd Nature",
                "src": "http://www.youtube.com/watch?v=w4c8Xi56YZ8",
                "embed": true
            },
            {
                "title": "Trevor Loveys - Bra",
                "duration": 414,
                "description": "Trevor Loveys - Bra",
                "src": "http://www.youtube.com/watch?v=DcakkW0uZcs",
                "embed": true
            },
            {
                "title": "Trevor Loveys - We can make it",
                "duration": 463,
                "description": "Trevor Loveys - We can make it",
                "src": "http://www.youtube.com/watch?v=lJN7Wpl6HrE",
                "embed": true
            },
            {
                "title": "Trevor Loveys Forever After (ERA).mp4",
                "duration": 311,
                "description": "Trevor Loveys Forever After (ERA).mp4",
                "src": "http://www.youtube.com/watch?v=00qmrYHgm54",
                "embed": true
            }
        ]
    },
    "labels": {
        "label": {
            "catno": "ALO CD003",
            "name": "Alola"
        }
    },
    "companies": "",
    "styles": {
        "style": [
            "Deep House",
            "Downtempo"
        ]
    },
    "formats": {
        "format": {
            "text": "",
            "name": "CD",
            "qty": 1,
            "descriptions": {
                "description": "Album"
            }
        }
    },
    "country": "UK",
    "id": 1504,
    "released": "1999-00-00",
    "artists": {
        "artist": [
            {
                "id": 2049,
                "anv": "",
                "name": "Trevor Loveys",
                "role": "",
                "tracks": "",
                "join": "Presents"
            },
            {
                "id": 8637,
                "anv": "2nd Nature",
                "name": "Second Nature",
                "role": "",
                "tracks": "",
                "join": ""
            }
        ]
    },
    "title": "Era",
    "master_id": 11157,
    "tracklist": {
        "track": [
            {
                "position": 1,
                "duration": "",
                "title": "Forever After"
            },
            {
                "position": 2,
                "duration": "",
                "title": "Wisdom"
            },
            {
                "position": 3,
                "duration": "",
                "title": "Look To The Sky"
            },
            {
                "position": 4,
                "duration": "",
                "title": "Falling Down"
            },
            {
                "position": 5,
                "duration": "",
                "title": "Life Stories"
            },
            {
                "position": 6,
                "duration": "",
                "title": "Rainy Afternoon"
            },
            {
                "position": 7,
                "duration": "",
                "title": "Reflections"
            },
            {
                "position": 8,
                "duration": "",
                "title": "Got To Go There"
            },
            {
                "position": 9,
                "duration": "",
                "title": "We Can Make It"
            },
            {
                "position": 10,
                "duration": "",
                "title": "No Compromise"
            },
            {
                "position": 11,
                "duration": "",
                "title": "Era"
            },
            {
                "position": 12,
                "duration": "",
                "title": "City 2 City"
            },
            {
                "position": 13,
                "duration": "",
                "title": "Depth Charge"
            }
        ]
    },
    "data_quality": "Correct",
    "extraartists": {
        "artist": [
            {
                "id": 49433,
                "anv": "",
                "name": "Chris Pedley",
                "role": "Written-By, Producer",
                "tracks": "",
                "join": ""
            },
            {
                "id": 2049,
                "anv": "",
                "name": "Trevor Loveys",
                "role": "Written-By, Producer",
                "tracks": "",
                "join": ""
            }
        ]
    }
}
}

我的目的是获取艺术家的专辑名称"Trevor Loveys"

我用上面的方法达到了我的目的。但是，我无法理解为什么会失败。

Answer 1

reduce 函数中的键是一个数组，如：

[["some_key","89a85cad58c426cd85a55bac8e0350f8"]]

您可以在您的 reduce 函数中使用 log(key) 来测试它。

因此您的 if 块失败并且没有 reduce 被返回。

简单的 reduce 函数不起作用，我在 couchDB 中的 reduce 函数代码有什么问题？

SImple reduce function is not working, what is wrong with my reduce function code in couchDB?

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