mongodb - 如何求和字段的值？

Question

我有这样的结构

  {
        "actionName": "add_new_paint_layer",
        "countUse": 1,
        "sources": "smth"
    },
    {
        "actionName": "clear",
        "countUse": 1,
        "sources": "smth"
    },
   {
        "actionName": "clear",
        "countUse": 5,
        "sources": "smth"
    },

如何对 actionName“clear”求和“countUse”？

Answer 1

db.collection.aggregate([
  {$match:
    {'actionName': 'clear'},
  {$group:
     {_id: "$actionName",
     total_count:{ $sum: "$countUse"}}}
])