如何使用数据库命令重命名数组中的字段? [英] How to rename a field inside an array with database commands?

问题描述

免责声明:尽管相似，但与MongoDB 重命名数组内的数据库字段.

Disclaimer: Even though similar, not the same as MongoDB rename database field within array.

我想使用 数据库命令 而不是 shell.我发现使用 $rename 是不可能的数组内.所以我转向 $set 和 $unset 并创建了这个:

I want to change the key of a field from name to title with database commands and NOT the shell. I found out that using $rename is not possible inside an array. So I turned to $set and $unset and created this:

db.runCommand({
    update: 'apps',
    updates: [
        {
            q: {versions: {$elemMatch: {title: {$exists: false}}}},
            u: {
                $set: {'versions.$.title': '$name'}
            },
            multi: true
        },
        {
            q: {versions: {$elemMatch: {name: {$exists: true}}}},
            u: {
                $unset: {'versions.$.name': ''}
            },
            multi: true
        }
    ]
})

这有点作用.它完成了我想要的一切，但它将每个标题/名称更改为字符串$name"；而不是字段 name 的值.

This works somewhat. It does all I want but it changes every title/name to the string "$name" instead of the value of the field name.

我也试过这个:

db.runCommand({
    update: 'apps',
    updates: [
        {
            q: {versions: {$elemMatch: {title: {$exists: false}}}},
            u: {
                $set: {
                    versions: {
                        $map: {
                            input: "versions",
                            as: 'each',
                            in: {
                                "title": "$$each.name"
                            }
                        }
                    }
                }
            },
            multi: true
        },
        {
            q: {versions: {$elemMatch: {name: {$exists: true}}}},
            u: {
                $unset: {'versions.$.name': ''}
            },
            multi: true
        }
    ]
})

但这只会导致 ['versions.$map' 中的美元 ($) 前缀字段 '$map' 对存储无效.].我将如何重命名数组中的字段?

But that just results in [The dollar ($) prefixed field '$map' in 'versions.$map' is not valid for storage.]. How would I go about renaming a field inside an array?

以下是我的应用程序集的缩小版本以供参考.我真的只想将每个名为 name 的键更改为 title.

Below is a minified version of my apps collection for reference. I literally only want to change every key called name into title.

[{
  identifier: "x",
  versions: [
    {
      name: "test_name"
      version: "x.x.x"
    },
    {
      name: "test_name"
      version: "x.x.x"
    },
  ]
},
{
  identifier: "y",
  versions: [
    {
      name: "test_name2"
      version: "x.x.x"
    },
    {
      name: "test_name2"
      version: "x.x.x"
    },
  ]
}, ... ]

推荐答案

但这只会导致 'versions.$map' 中以美元 ($) 为前缀的字段 '$map' 对存储无效..

• 错误说$map 的input 接受使用$ 符号的引用字段$version,
• 将 u 对象括在数组括号中，用于 使用聚合管道更新
• 只需将字段 title 和 version 放在 $map
中
• $unset 不是必需的，因为 $map 将用 in
中的新字段替换旧数据
• The error says $map's input accepts reference field using $ sign $version,
• enclose the u object in array bracket for update with an aggregation pipeline
• just put both field title and version in $map
• $unset is not required because $map will replace old data with new fields in in

db.runCommand({
    update: 'apps',
    updates: [
        {
            q: { "versions.name": { $exists: true } },
            u: [{
                $set: {
                    versions: {
                        $map: {
                            input: "$versions",
                            in: {
                                "title": "$$this.name",
                                "version": "$$this.version"
                            }
                        }
                    }
                }
            }],
            multi: true
        }
    ]
})

游乐场

第二种方式，更动态的方法

Second way, For more dynamic approach

• $mergeObjects 在 $map 内，防止手动列出键值对
• $unset 阶段从 version 数组中删除 name 字段
• $mergeObjects inside $map, to prevent manual list of key-values pair
• $unset stage to remove name field from version array

db.runCommand({
    update: 'apps',
    updates: [
        {
            q: { "versions.name": { $exists: true } },
            u: [
              {
                $set: {
                    versions: {
                        $map: {
                            input: "$versions",
                            in: {
                                $mergeObjects: [
                                    "$$this",
                                    { "title": "$$this.name" }
                                ]
                            }
                        }
                    }
                }
              },
              { $unset: "versions.name" }
            ],
            multi: true
        }
    ]
})

游乐场

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