Question

我想要做的就是按DateEntered和Role分组并获取计数。下面的代码可以工作，但是在完整日期的组到第二个。我需要按天分组（MM / DD / YYYY）

我也想使用Lambda表达式。

先谢谢你。

var group = new BsonDocument { 
            { "_id", new BsonDocument 
                { 
                    { "DateEntered", "$DateEntered" }, 
                    { "Role", "$Role" }, 
                }        
            }, 
            { "Count", new BsonDocument("$sum", 1) } 
                            };

var result = _collection.Aggregate()
                .Group(group)
                .ToListAsync().Result;

Answer 1

我从这个例子中找到了答案 Mongodb aggregate not grouping documents by date

function lowerBound(arr, target) {
    var first = 0, 
        count = arr.length;

    while (count > 0) {
        var step = count / 2;
        var it = first + step;

        if (arr[it] < target) {
            first = it + 1;
            count -= step + 1;
        } else {
            count = step;
        }
    }

    return first;
}

function distanceSort(arr, target) {
    var answer = [];

    var j = lowerBound(arr, target);
    var i = j-1;

    while (i >= 0 || j<arr.length) {
        if (j >= arr.length || target-arr[i]<arr[j]-target)
            answer.push(arr[i--]);
        else
            answer.push(arr[j++]);
    }
    return answer;
}

console.log(distanceSort([-10,-6,3,5], 1));   //[3, 5, -6, -10]
console.log(distanceSort([-10,-6,3,5], -11)); //[-10, -6, 3, 5]
console.log(distanceSort([-10,-6,3,5], -10)); //[-10, -6, 3, 5]
console.log(distanceSort([-10,-6,3,5], 5));   //[5, 3, -6, -10]
console.log(distanceSort([-10,-6,3,5], 6));   //[5, 3, -6, -10]

C＃MongoDB组（聚合）按日期

1 个答案: