Select from collection a on clause from JOIN on collection b
1
I have two collections: games and questions
game schema:
{
_id: ObjectId,
status: 'played',
questions:
[
{ questionId: ObjectId(questions._id) } // ref to questions collection by _id field
]
}
questions schema:
{
_id: ObjectId(),
text: foobar
}
Game could have two statuses: 'active' and 'played'.
My goal is to get all 'played' questions, means, questions, associated with games with status 'played'.
I've tried to make queries on games collection, tried to make queries on questions but none of them worked.
Some of them are:
db.games.aggregate([
{$match: {status: {$ne: 'played'}}},
{
$lookup:
{
from: 'questions',
localField: 'questions.questionId',
foreignField: '_id',
as: 'game_questions'
}
},
{$project: {game_questions: 1}},
{$unwind: {path: '$game_questions', preserveNullAndEmptyArrays: false}}
])
Or
db.questions.aggregate([
{ $project: {text: 1}},
{ $lookup: {
from: 'games',
pipeline: [
{ $match: {status:'played' }},
{ $project: { status: 1 }}
],
as: 'game_data'
}}
])
Bottom line:
After the request I'd like to get a list with questions, where game status is 'played'.
mongodb mongoose mongodb-query aggregation-framework
edited Nov 14 '18 at 21:22
Neil Lunn
98.6k23175184
asked Nov 14 '18 at 16:51
GrynetsGrynets
1,161826
add a comment |
1
I have two collections: games and questions
game schema:
{
_id: ObjectId,
status: 'played',
questions:
[
{ questionId: ObjectId(questions._id) } // ref to questions collection by _id field
]
}
questions schema:
{
_id: ObjectId(),
text: foobar
}
Game could have two statuses: 'active' and 'played'.
My goal is to get all 'played' questions, means, questions, associated with games with status 'played'.
I've tried to make queries on games collection, tried to make queries on questions but none of them worked.
Some of them are:
db.games.aggregate([
{$match: {status: {$ne: 'played'}}},
{
$lookup:
{
from: 'questions',
localField: 'questions.questionId',
foreignField: '_id',
as: 'game_questions'
}
},
{$project: {game_questions: 1}},
{$unwind: {path: '$game_questions', preserveNullAndEmptyArrays: false}}
])
Or
db.questions.aggregate([
{ $project: {text: 1}},
{ $lookup: {
from: 'games',
pipeline: [
{ $match: {status:'played' }},
{ $project: { status: 1 }}
],
as: 'game_data'
}}
])
Bottom line:
After the request I'd like to get a list with questions, where game status is 'played'.
mongodb mongoose mongodb-query aggregation-framework
edited Nov 14 '18 at 21:22
Neil Lunn
98.6k23175184
asked Nov 14 '18 at 16:51
GrynetsGrynets
1,161826
add a comment |
1
1
1
I have two collections: games and questions
game schema:
{
_id: ObjectId,
status: 'played',
questions:
[
{ questionId: ObjectId(questions._id) } // ref to questions collection by _id field
]
}
questions schema:
{
_id: ObjectId(),
text: foobar
}
Game could have two statuses: 'active' and 'played'.
My goal is to get all 'played' questions, means, questions, associated with games with status 'played'.
I've tried to make queries on games collection, tried to make queries on questions but none of them worked.
Some of them are:
db.games.aggregate([
{$match: {status: {$ne: 'played'}}},
{
$lookup:
{
from: 'questions',
localField: 'questions.questionId',
foreignField: '_id',
as: 'game_questions'
}
},
{$project: {game_questions: 1}},
{$unwind: {path: '$game_questions', preserveNullAndEmptyArrays: false}}
])
Or
db.questions.aggregate([
{ $project: {text: 1}},
{ $lookup: {
from: 'games',
pipeline: [
{ $match: {status:'played' }},
{ $project: { status: 1 }}
],
as: 'game_data'
}}
])
Bottom line:
After the request I'd like to get a list with questions, where game status is 'played'.
mongodb mongoose mongodb-query aggregation-framework
edited Nov 14 '18 at 21:22
Neil Lunn
98.6k23175184
asked Nov 14 '18 at 16:51
GrynetsGrynets
1,161826
I have two collections: games and questions
game schema:
{
_id: ObjectId,
status: 'played',
questions:
[
{ questionId: ObjectId(questions._id) } // ref to questions collection by _id field
]
}
questions schema:
{
_id: ObjectId(),
text: foobar
}
Game could have two statuses: 'active' and 'played'.
My goal is to get all 'played' questions, means, questions, associated with games with status 'played'.
I've tried to make queries on games collection, tried to make queries on questions but none of them worked.
Some of them are:
db.games.aggregate([
{$match: {status: {$ne: 'played'}}},
{
$lookup:
{
from: 'questions',
localField: 'questions.questionId',
foreignField: '_id',
as: 'game_questions'
}
},
{$project: {game_questions: 1}},
{$unwind: {path: '$game_questions', preserveNullAndEmptyArrays: false}}
])
Or
db.questions.aggregate([
{ $project: {text: 1}},
{ $lookup: {
from: 'games',
pipeline: [
{ $match: {status:'played' }},
{ $project: { status: 1 }}
],
as: 'game_data'
}}
])
Bottom line:
After the request I'd like to get a list with questions, where game status is 'played'.
mongodb mongoose mongodb-query aggregation-framework
mongodb mongoose mongodb-query aggregation-framework
edited Nov 14 '18 at 21:22
Neil Lunn
98.6k23175184
asked Nov 14 '18 at 16:51
GrynetsGrynets
1,161826
edited Nov 14 '18 at 21:22
Neil Lunn
98.6k23175184
asked Nov 14 '18 at 16:51
GrynetsGrynets
1,161826
edited Nov 14 '18 at 21:22
Neil Lunn
98.6k23175184
edited Nov 14 '18 at 21:22
Neil Lunn
98.6k23175184
edited Nov 14 '18 at 21:22
Neil Lunn
98.6k23175184
98.6k23175184
asked Nov 14 '18 at 16:51
GrynetsGrynets
1,161826
asked Nov 14 '18 at 16:51
GrynetsGrynets
1,161826
asked Nov 14 '18 at 16:51
GrynetsGrynets
1,161826
1,161826
add a comment |
add a comment |
1 Answer
1
active
oldest
votes
2
You can use $unwind and $replaceRoot with the data found in $lookup stage
db.games.aggregate([
{ "$match": { "status": "played" }},
{ "$lookup": {
"from": "questions",
"let": { "questions": "$questions.questionId" },
"pipeline": [
{ "$match": { "$expr": { "$in": ["$_id", "$$questions"] }}}
],
"as": "game_data"
}},
{ "$unwind": "$game_data" },
{ "$replaceRoot": { "newRoot": "$game_data" }}
])
Or
db.games.aggregate([
{ "$match": { "status": "played" }},
{ "$lookup": {
"from": "questions",
"localField": "questions.questionId",
"foreignField": "_id",
"as": "game_data"
}},
{ "$unwind": "$game_data" },
{ "$replaceRoot": { "newRoot": "$game_data" }}
])
edited Nov 15 '18 at 8:15
Grynets
1,161826
answered Nov 14 '18 at 17:01
Anthony WinzletAnthony Winzlet
16.9k41744
Any particular reason to use the first $lookup over the second?
– Murilo
Nov 14 '18 at 17:25
@Murilo$lookupsyntax with thepipelineis a advanced version of older$lookup. It allows you to join with multiple conditions and can allow you to use all the aggregation operators. And also I do prefer more then the older one.
– Anthony Winzlet
Nov 14 '18 at 17:39
1
Ok. Thank you :)
– Murilo
Nov 14 '18 at 17:52
add a comment |
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1 Answer
1
active
oldest
votes
1 Answer
1
active
oldest
votes
active
oldest
votes
active
oldest
votes
2
You can use $unwind and $replaceRoot with the data found in $lookup stage
db.games.aggregate([
{ "$match": { "status": "played" }},
{ "$lookup": {
"from": "questions",
"let": { "questions": "$questions.questionId" },
"pipeline": [
{ "$match": { "$expr": { "$in": ["$_id", "$$questions"] }}}
],
"as": "game_data"
}},
{ "$unwind": "$game_data" },
{ "$replaceRoot": { "newRoot": "$game_data" }}
])
Or
db.games.aggregate([
{ "$match": { "status": "played" }},
{ "$lookup": {
"from": "questions",
"localField": "questions.questionId",
"foreignField": "_id",
"as": "game_data"
}},
{ "$unwind": "$game_data" },
{ "$replaceRoot": { "newRoot": "$game_data" }}
])
edited Nov 15 '18 at 8:15
Grynets
1,161826
answered Nov 14 '18 at 17:01
Anthony WinzletAnthony Winzlet
16.9k41744
Any particular reason to use the first $lookup over the second?
– Murilo
Nov 14 '18 at 17:25
@Murilo$lookupsyntax with thepipelineis a advanced version of older$lookup. It allows you to join with multiple conditions and can allow you to use all the aggregation operators. And also I do prefer more then the older one.
– Anthony Winzlet
Nov 14 '18 at 17:39
1
Ok. Thank you :)
– Murilo
Nov 14 '18 at 17:52
add a comment |
2
You can use $unwind and $replaceRoot with the data found in $lookup stage
db.games.aggregate([
{ "$match": { "status": "played" }},
{ "$lookup": {
"from": "questions",
"let": { "questions": "$questions.questionId" },
"pipeline": [
{ "$match": { "$expr": { "$in": ["$_id", "$$questions"] }}}
],
"as": "game_data"
}},
{ "$unwind": "$game_data" },
{ "$replaceRoot": { "newRoot": "$game_data" }}
])
Or
db.games.aggregate([
{ "$match": { "status": "played" }},
{ "$lookup": {
"from": "questions",
"localField": "questions.questionId",
"foreignField": "_id",
"as": "game_data"
}},
{ "$unwind": "$game_data" },
{ "$replaceRoot": { "newRoot": "$game_data" }}
])
edited Nov 15 '18 at 8:15
Grynets
1,161826
answered Nov 14 '18 at 17:01
Anthony WinzletAnthony Winzlet
16.9k41744
Any particular reason to use the first $lookup over the second?
– Murilo
Nov 14 '18 at 17:25
@Murilo$lookupsyntax with thepipelineis a advanced version of older$lookup. It allows you to join with multiple conditions and can allow you to use all the aggregation operators. And also I do prefer more then the older one.
– Anthony Winzlet
Nov 14 '18 at 17:39
1
Ok. Thank you :)
– Murilo
Nov 14 '18 at 17:52
add a comment |
2
2
2
You can use $unwind and $replaceRoot with the data found in $lookup stage
db.games.aggregate([
{ "$match": { "status": "played" }},
{ "$lookup": {
"from": "questions",
"let": { "questions": "$questions.questionId" },
"pipeline": [
{ "$match": { "$expr": { "$in": ["$_id", "$$questions"] }}}
],
"as": "game_data"
}},
{ "$unwind": "$game_data" },
{ "$replaceRoot": { "newRoot": "$game_data" }}
])
Or
db.games.aggregate([
{ "$match": { "status": "played" }},
{ "$lookup": {
"from": "questions",
"localField": "questions.questionId",
"foreignField": "_id",
"as": "game_data"
}},
{ "$unwind": "$game_data" },
{ "$replaceRoot": { "newRoot": "$game_data" }}
])
edited Nov 15 '18 at 8:15
Grynets
1,161826
answered Nov 14 '18 at 17:01
Anthony WinzletAnthony Winzlet
16.9k41744
You can use $unwind and $replaceRoot with the data found in $lookup stage
db.games.aggregate([
{ "$match": { "status": "played" }},
{ "$lookup": {
"from": "questions",
"let": { "questions": "$questions.questionId" },
"pipeline": [
{ "$match": { "$expr": { "$in": ["$_id", "$$questions"] }}}
],
"as": "game_data"
}},
{ "$unwind": "$game_data" },
{ "$replaceRoot": { "newRoot": "$game_data" }}
])
Or
db.games.aggregate([
{ "$match": { "status": "played" }},
{ "$lookup": {
"from": "questions",
"localField": "questions.questionId",
"foreignField": "_id",
"as": "game_data"
}},
{ "$unwind": "$game_data" },
{ "$replaceRoot": { "newRoot": "$game_data" }}
])
edited Nov 15 '18 at 8:15
Grynets
1,161826
answered Nov 14 '18 at 17:01
Anthony WinzletAnthony Winzlet
16.9k41744
edited Nov 15 '18 at 8:15
Grynets
1,161826
edited Nov 15 '18 at 8:15
Grynets
1,161826
edited Nov 15 '18 at 8:15
Grynets
1,161826
1,161826
answered Nov 14 '18 at 17:01
Anthony WinzletAnthony Winzlet
16.9k41744
answered Nov 14 '18 at 17:01
Anthony WinzletAnthony Winzlet
16.9k41744
answered Nov 14 '18 at 17:01
Anthony WinzletAnthony Winzlet
16.9k41744
16.9k41744
Any particular reason to use the first $lookup over the second?
– Murilo
Nov 14 '18 at 17:25
@Murilo$lookupsyntax with thepipelineis a advanced version of older$lookup. It allows you to join with multiple conditions and can allow you to use all the aggregation operators. And also I do prefer more then the older one.
– Anthony Winzlet
Nov 14 '18 at 17:39
1
Ok. Thank you :)
– Murilo
Nov 14 '18 at 17:52
add a comment |
Any particular reason to use the first $lookup over the second?
– Murilo
Nov 14 '18 at 17:25
@Murilo$lookupsyntax with thepipelineis a advanced version of older$lookup. It allows you to join with multiple conditions and can allow you to use all the aggregation operators. And also I do prefer more then the older one.
– Anthony Winzlet
Nov 14 '18 at 17:39
1
Ok. Thank you :)
– Murilo
Nov 14 '18 at 17:52
Any particular reason to use the first $lookup over the second?
– Murilo
Nov 14 '18 at 17:25
Any particular reason to use the first $lookup over the second?
– Murilo
Nov 14 '18 at 17:25
@Murilo
$lookup syntax with the pipeline is a advanced version of older $lookup. It allows you to join with multiple conditions and can allow you to use all the aggregation operators. And also I do prefer more then the older one.– Anthony Winzlet
Nov 14 '18 at 17:39
@Murilo
$lookup syntax with the pipeline is a advanced version of older $lookup. It allows you to join with multiple conditions and can allow you to use all the aggregation operators. And also I do prefer more then the older one.– Anthony Winzlet
Nov 14 '18 at 17:39
1
1
Ok. Thank you :)
– Murilo
Nov 14 '18 at 17:52
Ok. Thank you :)
– Murilo
Nov 14 '18 at 17:52
add a comment |
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