我正在尝试在临时编码步骤中使用 printjson
调试 mongoDB 查询。作为中间步骤,我能够从具有不同结构的三个集合中获得类似的 printjson
输出。我认为这允许我从现在开始对所有三个不同的集合使用通用代码。然而,这似乎不起作用。两个集合的行为符合预期,但第三个集合在后续编码步骤中却没有表现(使用 Object.keys
函数)。我有三个问题:
printjson
是一个很好的调试工具吗?- 为什么具有类似
printjson
输出的代码(作为临时步骤)在后续编码步骤中表现不同? - 如何更正
layouts3
中的查询代码以生成与layouts1
和layouts2
生成的结果相似的结果?
这三个不同的集合是:layouts1
、layouts2
和 layouts3
:
db.layouts1.insert({
"_id": ObjectId("58e574a768afb6085ec3a388"),
"positions": [{
"_id": ObjectId("58e55f0f68afb6085ec3a2cc"),
"cyan" : [{"unit": "08","side": "5","position": "Far","_id": ObjectId("58e55f0f68afb6085ec3a2d0")}],
"magenta": [{"unit": "08","side": "5","position": "Far","_id": ObjectId("58e55f0f68afb6085ec3a2cd")}],
"yellow": [{"unit": "08","side": "3","_id": ObjectId("58e55f0f68afb6085ec3a2ce")}],
"black": [{"unit": "08","side": "5","position": "Far","_id": ObjectId("58e55f0f68afb6085ec3a2cf")}]
}]
});
db.layouts2.insert({
"_id" : ObjectId("58e574a768afb6085ec3a388"),
"pages" : [{
"_id" : ObjectId("58e542fb68afb6085ec3a1d2"),
"positions" : [
{"cyan": [{ "unit" : "08", "side" : "5","position" : "Far","_id" : ObjectId("58e542fb68afb6085ec3a1d6")}]},
{"magenta": [{"unit" : "08","side" : "5","position" : "Drive Side Far","_id" : ObjectId("58e542fb68afb6085ec3a1d3")}]},
{"yellow": [{"unit" : "08","side" : "3","position" : "Far","_id" : ObjectId("58e542fb68afb6085ec3a1d4")}]},
{"black": [{"unit" : "08","side" : "5","position" : "Far","_id" : ObjectId("58e542fb68afb6085ec3a1d5")}]}
]
}]
});
db.layouts3.insert({
"_id": ObjectId("58e574a768afb6085ec3a388"),
"pages": [{
"_id": ObjectId("58e542fb68afb6085ec3a1d2"),
"positions": [{ "_id": ObjectId("58e55f0f68afb6085ec3a2cc"),
"cyan": [{ "unit": "08", "side": "5", "position": "Far", "_id": ObjectId("58e55f0f68afb6085ec3a2d0") }],
"magenta": [{ "unit": "08", "side": "5", "position": "Far", "_id": ObjectId("58e55f0f68afb6085ec3a2cd") }],
"yellow": [{ "unit": "08", "side": "3", "_id": ObjectId("58e55f0f68afb6085ec3a2ce") }],
"black": [{ "unit": "08", "side": "5", "position": "Far", "_id": ObjectId("58e55f0f68afb6085ec3a2cf") }]
}]}]});
下面是获取三个集合中每个集合的输出所需的代码,该输出似乎具有相似的数据结构(通过查看 printjson
输出来判断)。
db.layouts1.find().forEach(doc => { doc.positions = doc.positions
.map(position => { Object.keys(position) // Returns a new array conaining all keys for positions
.filter(positionKey => positionKey !== "_id") // Returns a new array without _id
.forEach(positionKey => { printjson(position[positionKey])})})})
db.layouts2.find().forEach(doc => { doc.pages = doc.pages
.map( page => { page.positions
.forEach( position => { Object.keys(position)
.forEach( positionKey => {printjson(position[positionKey])})})})})
db.layouts3.find().forEach(doc => { doc.pages = doc.pages
.map(page => { page.positions // page.positions mapped and is []
.forEach(position => { Object.keys(position) // returns one array with _id, cyan, magenta, etc.
.forEach(positionKey => { printjson(position[positionKey])})})})})
下面的代码适用于 layouts1
、layouts2
,但不适用于 layouts3
:
db.layouts1.find().forEach(doc => { doc.positions = doc.positions
.map(position => { Object.keys(position) // Returns a new array conaining all keys for positions
.filter(positionKey => positionKey !== "_id") // Returns a new array without _id
.forEach(positionKey => { position[positionKey]
.forEach(colorDetails => { printjson(Object.keys(colorDetails))
})})})})
db.layouts2.find().forEach(doc => { doc.pages = doc.pages
.map( page => { page.positions
.forEach( position => { Object.keys(position)
.forEach( positionKey => {position[positionKey]
.forEach( colorDetails => { printjson(Object.keys(colorDetails))}) }) })})})
以下不起作用。它会产生以下错误:TypeError:position[positionKey].forEach不是函数
db.layouts3.find().forEach(doc => { doc.pages = doc.pages
.map(page => { page.positions // page.positions mapped and is []
.forEach(position => {Object.keys(position)
.forEach(positionKey => { position[positionKey]
.forEach( colorDetails => { printjson(Object.keys(colorDetails))
})})})})})
最佳答案
printjson
似乎是一个很好的调试工具,它帮助我识别了问题- 实际上,代码有一些难以注意到的
printjson
输出。该代码不起作用,在输出顶部有ObjectId("58e55f0f68afb6085ec3a2cc")
生成与使用布局1和布局2生成的结果类似的结果所需的代码如下:
db.layouts3.find().forEach(doc => { doc.pages = doc.pages .map(page => { page.positions//page.positions 映射并且是 [] .forEach(位置 => {Object.keys(位置) //过滤需要的“_id”字段,去掉“_id”字段 .filter(positionKey =>positionKey !== "_id") .forEach(positionKey => { 位置[positionKey] .forEach( colorDetails => { printjson(Object.keys(colorDetails)) })})})})})
关于javascript - 在 mongo shell 中使用 printjson 进行 mongoDB 调试,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/44508256/