在创建了自己的聚合管道之后，我得到了以下结果:
[
{
"_id": "53712c7238b8d900008ef71c",
"address": [
{
"_id": "53712c7238b8d900008ef71b",
"phoneNumber": "4092348294",
...
}
],
"name": "TestDealer",
"vehicles": [
{
"_id": "53712fa138b8d900008ef720",
"createdAt": "2014-05-12T20:08:00.000Z",
"tags": [
"vehicle"
],
"opts": [
{
"_id": "53712fa138b8d900008ef71e",
"hasSunroof": false,
...
}
],
"listed": true,
"disclosures": [
{
"_id": "53712fa138b8d900008ef71f",
"waterDamage": false,
...
}
],
"details": [
{
"_id": "53712fa138b8d900008ef71d",
"year": 2007,
...
}
]
},
{
"_id": "5373c6439058859af7904a17",
"createdAt": "2014-05-14T19:17:00.000Z",
"tags": [
"vehicle"
],
"opts": [
{
"_id": "5373c6439058859af7904a15",
"hasSunroof": false,
....
"other": []
}
],
"listed": true,
"disclosures": [
{
"_id": "5373c6439058859af7904a16",
"waterDamage": false,
...
}
],
"details": [
{
"_id": "5373c6439058859af7904a14",
"year": 2013,
...
}
]
}
]
}
]
可以看到，vehicles是遵循特定模式的子文档(车辆)数组:
- details:
details子文档的数组 - options:一组
opts子文档 - 披露:
disclosures子文档的数组
对于details, disclosures和opts，我想返回数组中的第一个子文档，而不是数组。然而，我不确定从哪里开始。我真的不能$unwind车辆，因为它可能是空的。
我的最终数据应该是这样的:
[
{
"_id": "53712c7238b8d900008ef71c",
"address": [
{
"_id": "53712c7238b8d900008ef71b",
"phoneNumber": "4092348294",
...
}
],
"name": "TestDealer",
"vehicles": [
{
"_id": "53712fa138b8d900008ef720",
"createdAt": "2014-05-12T20:08:00.000Z",
"tags": [
"vehicle"
],
"opts": {
"_id": "53712fa138b8d900008ef71e",
"hasSunroof": false,
...
},
"listed": true,
"disclosures": {
"_id": "53712fa138b8d900008ef71f",
"waterDamage": false,
...
},
"details": {
"_id": "53712fa138b8d900008ef71d",
"year": 2007,
...
}
},
{
"_id": "5373c6439058859af7904a17",
"createdAt": "2014-05-14T19:17:00.000Z",
"tags": [
"vehicle"
],
"opts": {
"_id": "5373c6439058859af7904a15",
"hasSunroof": false,
....
"other": []
},
"listed": true,
"disclosures": {
"_id": "5373c6439058859af7904a16",
"waterDamage": false,
...
},
"details": {
"_id": "5373c6439058859af7904a14",
"year": 2013,
...
}
}
]
}
]
这是聚合我做得到我的数据(在CoffeeScript):
{
$match:
_id: ObjectId(params.id)
}
{
$unwind: '$inventories'
}
{
$match:
'inventories._id': 'active'
}
{
$redact:
$cond:
if:
$eq:['$listed',false]
then: '$$PRUNE'
else: '$$DESCEND'
}
{
$project:
address: 1
name: '$dealerName'
email: '$_id.email'
vehicles: '$inventories.vehicles'
}
以及原始数据:
{ "_id" : ObjectId( "53712c7238b8d900008ef71c" ),
"email" : "test@test.com",
"createdAt" : Date( 1399925280000 ),
"password" : "$2a$10$3dhicJuONkXeI9mQflXF0.JftAx7mLQaY2./6a3O7xdrs5qfH2zMW",
"firstName" : "TestName",
"lastName" : "testName",
"dealerName" : "TestDealer",
"dealerType" : "Franchised Dealer",
"emailIsVerified" : false,
"lastLoggedInAt" : Date( 1400247300000 ),
"expiresAt" : Date( 4524062882000 ),
"deletedAt" : null,
"updatedAt" : Date( 1400251500000 ),
"inventories" : [
{ "title" : "activeInventory",
"_id" : "active",
"vehicles" : [
{ "_id" : ObjectId( "53712fa138b8d900008ef720" ),
"createdAt" : Date( 1399925280000 ),
"tags" : [
"vehicle" ],
"opts" : [
{ "_id" : ObjectId( "53712fa138b8d900008ef71e" ),
"hasSunroof" : false,
"hasSnowTires" : false,
"hasPowerWindows" : false,
"hasNavigationSystem" : false,
"hasManuals" : false,
"hasMags" : false,
"hasLeather" : false,
"hasKeylessEntry" : false,
"hasHeatedSeats" : false,
"hasDvdSystem" : false,
"hasAirConditioning" : false,
"has2SetsOfKeys" : false,
"other" : [] } ],
"listed" : true,
"disclosures" : [
{ "_id" : ObjectId( "53712fa138b8d900008ef71f" ),
"waterDamage" : false,
"vehicleLien" : false,
"usVehicle" : false,
"totalLossByInsurer" : false,
"theftOrRecovery" : false,
"taxiOrLimo" : false,
"structuralPartsAreDamagedOrAlteredOrRepaired" : false,
"suspensionOrSubFrameNeedsRepair" : false,
"repainted" : false,
"previousDamageExceeding3k" : false,
"powerTrainNeedsRepair" : false,
"policeCruiser" : false,
"outOfProvinceOrState" : false,
"originalOwner" : false,
"originalManufacturerVinPlate" : false,
"originalSpecificationsChanged" : false,
"odometerRolledBackOrReplaced" : false,
"manufacturerWarrantyCancelled" : false,
"manufacturerBadgesChanged" : false,
"fuelSystemNeedsRepair" : false,
"fireDamage" : false,
"engineNeedsRepair" : false,
"emergencyVehicle" : false,
"electricalSystemNeedsRepair" : false,
"dailyRental" : false,
"computerNeedsRepair" : false,
"antiLockBrakesDamagedOrInoperable" : false,
"airbagIsMissingOrInoperable" : false,
"airConditioningNeedsRepair" : false } ],
"details" : [
{ "_id" : ObjectId( "53712fa138b8d900008ef71d" ),
"year" : 2007,
"vin" : "JN8AZ08W27W649264",
"trim" : "SE",
"transmission" : "Automatic",
"price" : 132123,
"model" : "Murano 4D Utility AWD",
"mileageReading" : 125000,
"make" : "Nissan",
"interiorColor" : "Black",
"history" : "Carproof Verified ($40.00)",
"hasAccident" : false,
"fuelType" : "Biodiesel",
"exteriorColor" : "Blue",
"driveTrain" : "FWD",
"description" : "dsadas",
"cylinders" : 4,
"mileageType" : "kms" } ] },
{ "_id" : ObjectId( "53713bfc1429925f0faf79d0" ),
"createdAt" : Date( 1399929780000 ),
"tags" : [
"vehicle" ],
"opts" : [
{ "_id" : ObjectId( "53713bfc1429925f0faf79ce" ),
"hasSunroof" : false,
"hasSnowTires" : false,
"hasPowerWindows" : false,
"hasNavigationSystem" : false,
"hasManuals" : false,
"hasMags" : false,
"hasLeather" : false,
"hasKeylessEntry" : false,
"hasHeatedSeats" : false,
"hasDvdSystem" : false,
"hasAirConditioning" : false,
"has2SetsOfKeys" : false,
"other" : [] } ],
"listed" : false,
"disclosures" : [
{ "_id" : ObjectId( "53713bfc1429925f0faf79cf" ),
"waterDamage" : false,
"vehicleLien" : false,
"usVehicle" : false,
"totalLossByInsurer" : false,
"theftOrRecovery" : false,
"taxiOrLimo" : false,
"structuralPartsAreDamagedOrAlteredOrRepaired" : false,
"suspensionOrSubFrameNeedsRepair" : false,
"repainted" : false,
"previousDamageExceeding3k" : false,
"powerTrainNeedsRepair" : false,
"policeCruiser" : false,
"outOfProvinceOrState" : false,
"originalOwner" : false,
"originalManufacturerVinPlate" : false,
"originalSpecificationsChanged" : false,
"odometerRolledBackOrReplaced" : false,
"manufacturerWarrantyCancelled" : false,
"manufacturerBadgesChanged" : false,
"fuelSystemNeedsRepair" : false,
"fireDamage" : false,
"engineNeedsRepair" : false,
"emergencyVehicle" : false,
"electricalSystemNeedsRepair" : false,
"dailyRental" : false,
"computerNeedsRepair" : false,
"antiLockBrakesDamagedOrInoperable" : false,
"airbagIsMissingOrInoperable" : false,
"airConditioningNeedsRepair" : false } ],
"details" : [
{ "_id" : ObjectId( "53713bfc1429925f0faf79cd" ),
"year" : 2007,
"vin" : "JN8AZ08W27W649264",
"trim" : "SE",
"transmission" : "Manual",
"price" : 13241234,
"model" : "Murano 4D Utility AWD",
"mileageReading" : 1312312,
"make" : "Mercedes-Benz",
"interiorColor" : "Black",
"history" : "Carproof Claims ($25.00)",
"hasAccident" : true,
"fuelType" : "Diesel",
"exteriorColor" : "Black",
"driveTrain" : "RWD",
"description" : "werwe",
"cylinders" : 4,
"mileageType" : "kms" } ] },
{ "_id" : ObjectId( "5373c6439058859af7904a17" ),
"createdAt" : Date( 1400095020000 ),
"tags" : [
"vehicle" ],
"opts" : [
{ "_id" : ObjectId( "5373c6439058859af7904a15" ),
"hasSunroof" : false,
"hasSnowTires" : false,
"hasPowerWindows" : false,
"hasNavigationSystem" : false,
"hasManuals" : false,
"hasMags" : false,
"hasLeather" : false,
"hasKeylessEntry" : false,
"hasHeatedSeats" : false,
"hasDvdSystem" : false,
"hasAirConditioning" : false,
"has2SetsOfKeys" : false,
"other" : [] } ],
"listed" : true,
"disclosures" : [
{ "_id" : ObjectId( "5373c6439058859af7904a16" ),
"waterDamage" : false,
"vehicleLien" : false,
"usVehicle" : false,
"totalLossByInsurer" : false,
"theftOrRecovery" : false,
"taxiOrLimo" : false,
"structuralPartsAreDamagedOrAlteredOrRepaired" : false,
"suspensionOrSubFrameNeedsRepair" : false,
"repainted" : false,
"previousDamageExceeding3k" : false,
"powerTrainNeedsRepair" : false,
"policeCruiser" : false,
"outOfProvinceOrState" : false,
"originalOwner" : false,
"originalManufacturerVinPlate" : false,
"originalSpecificationsChanged" : false,
"odometerRolledBackOrReplaced" : false,
"manufacturerWarrantyCancelled" : false,
"manufacturerBadgesChanged" : false,
"fuelSystemNeedsRepair" : false,
"fireDamage" : false,
"engineNeedsRepair" : false,
"emergencyVehicle" : false,
"electricalSystemNeedsRepair" : false,
"dailyRental" : false,
"computerNeedsRepair" : false,
"antiLockBrakesDamagedOrInoperable" : false,
"airbagIsMissingOrInoperable" : false,
"airConditioningNeedsRepair" : false } ],
"details" : [
{ "_id" : ObjectId( "5373c6439058859af7904a14" ),
"year" : 2013,
"vin" : "12345678901234567",
"trim" : "SE",
"transmission" : "Automatic",
"price" : 13564,
"model" : "Red",
"mileageReading" : 13453,
"make" : "Daihatsu",
"interiorColor" : "Black",
"history" : "Carproof Verified ($40.00)",
"hasAccident" : true,
"fuelType" : "Diesel",
"exteriorColor" : "Black",
"driveTrain" : "FWD",
"description" : "wrw",
"cylinders" : 3,
"mileageType" : "kms" } ] } ],
"tags" : [
"inventory",
"active",
"vehicles" ] },
{ "title" : "soldInventory",
"_id" : "sold",
"vehicles" : [],
"tags" : [
"inventory",
"sold",
"vehicles" ] },
{ "title" : "deletedInventory",
"_id" : "deleted",
"vehicles" : [],
"tags" : [
"inventory",
"deleted",
"vehicles" ] } ],
"address" : [
{ "_id" : ObjectId( "53712c7238b8d900008ef71b" ),
"phoneNumber" : "4092348294",
"country" : "Canada",
"zip" : "301111",
"region" : "Quebec",
"city" : "Montreal",
"street2" : "Apt. 101",
"street1" : "1213 Street",
"additionalNumbers" : [] } ],
"__v" : 3 }
如果你使用2.6(你必须使用$ react)，如果数组总是保证是空的，如果没有标签或选项，你可以使用这种技术，以确保你不会丢失车辆有空的数组，当你$unwind:
在$project阶段，为所有您希望$unwind只保留第一个元素的数组添加以下内容:
opts:{$cond:{if:{$eq:[{$size:"$opts"},0]}, then:{$literal:[ "none" ]}, else:"$opts"}}
对于每个子数组，你现在可以保留第一个子数组，然后对下一个子数组重复。
你需要小心地对每个数组分别展开和重新分组，以防止出现任何重复，如果你不聚合任何其他东西，你可以在一个单独的组中完成它，有多少子数组就有多少$unwinds。