我有以下查詢：match := bson.D{{"$match", bson.D{{"venue", venueID}}}}group := bson.D{{"$lookup", bson.M{ "from": "labels", "localField": "label_ids", "foreignField": "_id", "as": "labels",}}, {"$graphLookup", bson.M{ "from": "menus", "startWith": "$child_ids", "connectFromField": "child_ids", "connectToField": "_id", "as": "children", "maxDepth": 5, "depthField": "level",}}}cur, err := m.collection.Aggregate(ctx, mongo.Pipeline{group, match})我有兩個關(guān)系字段，其中一個是圖形結(jié)構(gòu)（菜單），每個父元素都有一個每個子元素的 ID 數(shù)組。第二個字段，標(biāo)簽，只是一個一對多的查詢。標(biāo)簽和菜單應(yīng)該是可重復(fù)使用的，因此不會嵌入到單個父實體中。上面概述的查詢對我來說很有意義，但是我收到以下錯誤：A pipeline stage specification object must contain exactly one field.謝謝！
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達(dá)令說
TA貢獻(xiàn)1821條經(jīng)驗 獲得超6個贊
MongoDB 管道中的每個元素都必須是單個階段，例如$match，$group等。
您的group元素包含 2 個階段：$lookup和$graphLookup.
拆分它們并單獨列出它們：
match := bson.D{{"$match", bson.D{{"venue", venueID}}}}
group := bson.D{{"$lookup", bson.M{
"from": "labels",
"localField": "label_ids",
"foreignField": "_id",
"as": "labels",
}}}
graphLookup := bson.D{{"$graphLookup", bson.M{
"from": "menus",
"startWith": "$child_ids",
"connectFromField": "child_ids",
"connectToField": "_id",
"as": "children",
"maxDepth": 5,
"depthField": "level",
}}}
cur, err := m.collection.Aggregate(ctx, mongo.Pipeline{group, graphLookup, match})
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