javascript - Mongodb查询: search regex in nested array

Question

鉴于录制的游戏的以下文档结构:

{
...
"rightkingpercenthp":[1,1,1,1,1,1,1,1,1,1,1,0.94,0.95,0],
"gameDetails":[
	{"playername":"Calvino",
	...
	"unitsPerWave":[
		["grarl_unit_id:0.5|9.5"],
		["hydra_unit_id:3.5|6.5","veteran_unit_id:1.5|6","grarl_unit_id:3.5|5.5","peewee_unit_id:8.5|7"],	       ["hydra_unit_id:3.5|6.5","veteran_unit_id:1.5|6","veteran_unit_id:8.5|7","peewee_unit_id:8.5|6",
    "fatalizer_unit_id:2.5|5"],
    ...
    ]
}

我如何计算至少有一个游戏的数量，例如gameDetails.unitsPerWave 中的“veteran_unit_id”(忽略名称后的坐标)？

Answer 1

您可以使用嵌套 $elemMatch用于在嵌套 gamesDetails.unitsPerWave 数组中查询的运算符以及与字符串开头匹配的正则表达式:

db.col.count({
    'gameDetails.unitsPerWave': {$elemMatch: {$elemMatch: {$regex: /^veteran_unit_id/}}}
})