pipeline := []bson.M{
bson.M{"$match": bson.M{"id": uid}},
bson.M{"$project": bson.M{"last_msg": 1, "_id": 0}},
bson.M{"$unwind": "$last_msg"},
bson.M{"$sort": bson.M{"last_msg": -1}},
bson.M{"$skip": 2},
bson.M{"$limit": 2},
}
userModel := MongoDb.C("user")
pipe := userModel.Pipe(pipeline)
var data []interface{}
err := pipe.All(&data)
fmt.Println(data)
fmt.Println(len(data))
等效于
db.getCollection("user").aggregate([
{$match: {"id":"1"}},
{$project:{"last_msg":1, "_id":0}},
{$unwind: "$last_msg"},
{$sort: {"last_msg.date":-1}},
{$skip:2},
{$limit:2}
]);
mongodb表结构：
其中一条数据：
{
"_id": ObjectId("5d2b24c16197934ef6db77ba"),
"id": "1",
"account": "你的女神",
"passwd": "5d78eb174d633345054faf7d56a612ed",
"friends": [
{
"uid": "2"
},
{
"uid": "3"
}
],
"last_msg": [
{
"date": "1234567890",
"from_id": "2",
"msg": "在么"
},
{
"date": "1234567895",
"from_id": "3",
"msg": "女神"
},
{
"date": "1234567898",
"from_id": "4",
"msg": "求你了，理理我好么"
},
{
"date": "1234567999",
"from_id": "5",
"msg": "你是不是在和别人..."
}
]
}