多參數mongodb查詢

Question

找到最便宜且具有最高評分數量且具有最高平均評分的項目。這是做這件事的正確方法嗎？

exports.getBestEconomicalProject = function(number, callback){ 
    var result = ProjectModel.find().sort({averageCost: 1}, {ratingCount : -1}, {averageRating : -1}).select({_id: 1}).limit(number).exec(
      function(err, projects) { 
       callback(null, projects) 
      } 
     ); 
    return result; 
} 

Answer 1

你需要的所有sort項合併爲一個單一的對象：

exports.getBestEconomicalProject = function(number, callback){ 
    var result = ProjectModel.find() 
     .sort({averageCost: 1, ratingCount : -1, averageRating : -1}) 
     .select({_id: 1}) 
     .limit(number) 
     .exec(
      function(err, projects) { 
       callback(null, projects) 
      } 
     ); 
    return result; 
} 

或使用該sort字符串格式：

exports.getBestEconomicalProject = function(number, callback){ 
    var result = ProjectModel.find() 
     .sort('averageCost -ratingCount -averageRating') 
     .select({_id: 1}) 
     .limit(number) 
     .exec(
      function(err, projects) { 
       callback(null, projects) 
      } 
     ); 
    return result; 
}