使用$all和$not运算符

Question

我想找到所有缺少数组中至少一个值的文档。例如：

数组：["spanish", "dutch", "french"]

应选择以下文档：

{
    translations: [{ language: "spanish" }]
}
//and
{
    translations: [{ language: "spanish" }, { language: "french" }]
}
//and
{
    translations: [{ language: "german" }]
}

但是应该不选择这些内容：

{
    translations: [{ language: "spanish" }, { language: "french" }, { language: "dutch" }]
}
//and
{
    translations: [{ language: "spanish" }, { language: "french" }, { language: "dutch" }, { language: "german" }]
}

Answer 1

您可以使用$setIntersection查找与$size相交小于三个的文档

{$expr : 
    {$lt :[
        {$size :{$setIntersection : ["$translations.language", ["spanish", "dutch", "french"]]}},
        3
    ]}
}

> db.t80.find()
{ "_id" : ObjectId("5c68552ac6f8be1a888e6cc7"), "translations" : [ { "language" : "spanish" } ] }
{ "_id" : ObjectId("5c68552ac6f8be1a888e6cc8"), "translations" : [ { "language" : "spanish" }, { "language" : "french" } ] }
{ "_id" : ObjectId("5c68552ac6f8be1a888e6cc9"), "translations" : [ { "language" : "german" } ] }
{ "_id" : ObjectId("5c68552ac6f8be1a888e6cca"), "translations" : [ { "language" : "spanish" }, { "language" : "french" }, { "language" : "dutch" } ] }
{ "_id" : ObjectId("5c68552ac6f8be1a888e6ccb"), "translations" : [ { "language" : "spanish" }, { "language" : "french" }, { "language" : "dutch" }, { "language" : "german" } ] }
>

结果

> db.t80.find({$expr  : {$lt :[{$size :{$setIntersection : ["$translations.language", ["spanish", "dutch", "french"]]}},3]}})
{ "_id" : ObjectId("5c68552ac6f8be1a888e6cc7"), "translations" : [ { "language" : "spanish" } ] }
{ "_id" : ObjectId("5c68552ac6f8be1a888e6cc8"), "translations" : [ { "language" : "spanish" }, { "language" : "french" } ] }
{ "_id" : ObjectId("5c68552ac6f8be1a888e6cc9"), "translations" : [ { "language" : "german" } ] }
>

Answer 2

使用$all和$not运算符

$all返回包含某个键的所有项，这些键具有目标数组中的所有项
$not则相反。由于至少一个缺少的=不包含全部

查询如下：

{ "translations.language": { $not: { $all: ["spanish", "dutch", "french"] } } }

对于Mongoose和Node.js，它看起来像这样：

const target = ["spanish", "dutch", "french"];

Lang.find({ "translations.language": { $not: { $all: target } } })
  .then(console.log)
  .catch(console.error);

Answer 3

替代解决方案：

db.docs.find({$or: [
 {translations: {$not: {$elemMatch: {language: "spanish"}}}},
 {translations: {$not: {$elemMatch: {language: "dutch"}}}},
 {translations: {$not: {$elemMatch: {language: "french"}}}},
]})

MongoDB-查找至少缺少一个数组值的位置

3 个答案:

使用$all和$not运算符