我试图通过向我的3个集合传递3个不同的链接来检索3个食物清单,例如
redFoods = collection1.find(redLink)
blueFoods = collection2.find(blueLink)
greenFoods = collection3.find(greenLink)
Where
redFoods = [red1, red2, red3, ... , redN]
blueFoods = [blue1, blue2, blue3, ... , blueN]
greenFoods = [green1, green2, green3, ... , greenN]
然后,我想把redFoods、blueFoods和greenFoods合并为一个列表,将食物交替使用。
[red1, blue1, green1, red2, blue2, green2, red3, blue3, ... , redN, blueN, greenN]
我怎样才能通过MongoDB在一个查询步骤中做到这一点?
到目前为止,我已经试过了,但这似乎并不奏效。
redLink = "meat"
blueLink = "fruit"
greenLink = "veggies"
shoesList = redFoods.aggregate([
'$match': {
'Link': {
redLink
'$unionWith': {
'coll': 'blueFoods',
'pipeline': [
'$match': {
'Link': {
blueLink
'$unionWith': {
'coll': 'greenFoods',
'pipeline': [
'$match': {
'Link': {
greenLink
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'$match': {
$or: [
{ 'Link': redLink },