Javascript mongoose中的内部连接2个表
我试图做一个匹配的内部连接,但由于某种原因,我得到了一个左连接。 我有两个关系表,我想得到具有类型名称的电影 考虑以下模型:Javascript mongoose中的内部连接2个表,javascript,node.js,mongoose,inner-join,lookup,Javascript,Node.js,Mongoose,Inner Join,Lookup,我试图做一个匹配的内部连接,但由于某种原因,我得到了一个左连接。 我有两个关系表,我想得到具有类型名称的电影 考虑以下模型: // Movie const MovieSchema = new mongoose.Schema({ id: { type: Number, default: null, required: true, unique: true }, title: { type: St
// Movie
const MovieSchema = new mongoose.Schema({
id: {
type: Number,
default: null,
required: true,
unique: true
},
title: {
type: String,
default: null,
required: true,
unique: true,
trim: true
},
});
const Movie = mongoose.model('Movie', MovieSchema);
module.exports = Movie;
// Genre
const GenreSchema = new mongoose.Schema({
id: {
type: Number,
default: null,
required: true,
unique: true
},
name: {
type: String,
default: null,
required: false,
trim: true,
unique: true
}
});
const Genre = mongoose.model('Genre', GenreSchema);
module.exports = Genre;
// MovieGenre
const MovieGenreSchema = new mongoose.Schema({
genreId: {
type: Number,
default: null,
required: true
},
movieId: {
type: Number,
default: null,
required: true
}
});
const MovieGenre = mongoose.model('MovieGenre', MovieGenreSchema);
module.exports = MovieGenre;
我尝试执行以下查询:
{
$lookup:
{
from: MovieGenre.collection.name,
localField: 'id',
foreignField: 'movieId',
as: 'movieGenres'
}
},
{
$lookup: {
from: Genre.collection.name,
localField: 'g.id',
foreignField: 'genreId',
as: 'genreNames'
}
},
{
$match: {
'genreNames.name': 'Action'
}
}
我得到的结果是:
{
_id: 5ee9b51609f44c0f38262c94,
id: 26583,
title: 'The Keeper',
__v: 0,
movieGenres: [
{
_id: 5ee8b8cf0d186c20b4bf3ccd,
genreId: 28,
movieId: 26583,
__v: 0
},
{
_id: 5ee8b8cf0d186c20b4bf3cce,
genreId: 53,
movieId: 26583,
__v: 0
}
],
genreNames: [
{ _id: 5ee8b68f0d186c20b4b03a3d, id: 35, name: 'Comedy', __v: 0 },
{ _id: 5ee8b68f0d186c20b4b03a3e, id: 80, name: 'Crime', __v: 0 },
{ _id: 5ee8b68f0d186c20b4b03a40, id: 18, name: 'Drama', __v: 0 },
{ _id: 5ee8b68f0d186c20b4b03a42, id: 53, name: 'Thriller', __v: 0 },
{ _id: 5ee8b68f0d186c20b4b03a43, id: 28, name: 'Action', __v: 0 },
{ _id: 5ee8b68f0d186c20b4b03a45, id: 14, name: 'Fantasy', __v: 0 },
{ _id: 5ee8b68f0d186c20b4b03a46, id: 27, name: 'Horror', __v: 0 },
{ _id: 5ee8b68f0d186c20b4b03a4a, id: 10752, name: 'War', __v: 0 },
{ _id: 5ee8b68f0d186c20b4b03a4b, id: 10402, name: 'Music', __v: 0 },
{ _id: 5ee8b68f0d186c20b4b03a4c, id: 37, name: 'Western', __v: 0 },
{ _id: 5ee8b68f0d186c20b4b03a4d, id: 36, name: 'History', __v: 0 }
]
}
但我希望得到的是:
{
_id: 5ee9b51609f44c0f38262c94,
id: 26583,
title: 'The Keeper',
__v: 0,
movieGenres: [
{
_id: 5ee8b8cf0d186c20b4bf3ccd,
genreId: 28,
movieId: 26583,
__v: 0
},
{
_id: 5ee8b8cf0d186c20b4bf3cce,
genreId: 53,
movieId: 26583,
__v: 0
}
],
genreNames: [
{ _id: 5ee8b68f0d186c20b4b03a43, id: 28, name: 'Action', __v: 0 },
{ _id: 5ee8b68f0d186c20b4b03a42, id: 53, name: 'Thriller', __v: 0 },
]
}
你能告诉我吗,
我做错了什么?
谢谢。您只需使用流派集更正第二次查找,我添加了两种方法,您可以使用任何人 1) 使用您的方法:
传递上一次查找结果的localField
movieGenres.genreId
passforeignField
id
name
从上面的查找中筛选genrename
名称
迭代$filter
数组的循环,并按genreNames
name:Action
{
$lookup: {
from: MovieGenre.collection.name,
localField: "id",
foreignField: "movieId",
as: "movieGenres"
}
},
{
$lookup: {
from: Genre.collection.name,
localField: "movieGenres.genreId",
foreignField: "id",
as: "genreNames"
}
},
{
$match: {
"genreNames.name": "Action"
}
},
{
$addFields: {
genreNames: {
$filter: {
input: "$genreNames",
cond: { $eq: ["$$this.name", "Action"] }
}
}
}
}
2) 使用管道查找方法: 另一种方法是
从上面的查找中传递让
movieGenres.genreId
使用$match
表达式匹配和$expr
字段匹配name
,并使用genreId
操作组合条件$and
{
$addFields: {
genreNames: {
$filter: {
input: "$genreNames",
cond: { $eq: ["$$this.name", "Action"] }
}
}
}
}
{
$lookup: {
from: MovieGenre.collection.name,
localField: "id",
foreignField: "movieId",
as: "movieGenres"
}
},
{
$lookup: {
from: Genre.collection.name,
localField: "movieGenres.genreId",
foreignField: "id",
as: "genreNames"
}
},
{
$match: {
"genreNames.name": "Action"
}
},
{
$addFields: {
genreNames: {
$filter: {
input: "$genreNames",
cond: { $eq: ["$$this.name", "Action"] }
}
}
}
}
{
$lookup: {
from: MovieGenre.collection.name,
localField: "id",
foreignField: "movieId",
as: "movieGenres"
}
},
{
$lookup: {
from: Genre.collection.name,
let: { genreIds: "$movieGenres.genreId" },
pipeline: [
{
$match: {
$and: [
{ $expr: { $in: ["$id", "$$genreIds"] } },
{ name: "Action" }
]
}
}
],
as: "genreNames"
}
}