组合/聚合查询与解析云代码 [英] Group By / Sum Aggregate Query with Parse Cloud Code

问题描述

我在我的Parse数据库中有Inventory表，有两个相关字段：productId和quantity。收到货件时，将创建包含productId和数量的记录。类似地，当销售发生时，使用productId和数量（其将是负的，因为在销售之后库存将减少）进行库存记录。

我想使用Parse Cloud Code在Inventory表上运行group by / sum聚合查询，输出包含唯一productIds作为键的字典，

我已经看到一些老帖子说Parse不这样做，但更新的帖子指的是云代码作为cloud代码指南中的averageStart： https://parse.com/docs/cloud_code_guide

然而，似乎Parse.Query在averageStars中使用的最大限制为1000条记录。因此，当我总数量列，我只这样做1000记录，而不是整个表。有没有一种方法，我可以通过/ sum在清单表中的所有记录计算组？

---

：

库存表

productId数量 / p>

记录1：AAAAA 50

记录2：BBBBB 40

记录3：AAAAA -5

记录4：BBBBB -2

记录5：AAAAA 10

记录6：AAAAA -7

输出字典：
{AAAAA： 48，BBBBB：38}

解决方案

您可以使用 Parse.Query.each ）。没有限制。如果您的课程太多，则会超时。

请参阅 docs

例如：

  var totalQuantity = 0; 
 var inventoryQuery = new Parse.Query（Inventory）; 
 inventoryQuery.each（
 function（result）{
 totalQuantity + = result.get（quantity）; 
}，{
 success：function（）{ 
 //循环通过一切
}，
错误：function（error）{
 //错误是Parse.Error的一个实例
} 
 }）; 
}）; 
  

如果超时，您必须构建类似 this 。

I have Inventory table in my Parse database with two relevant fields: productId and quantity. When a shipment is received, a record is created containing the productId and quantity. Similarly, when a sale occurs, an inventory record is made with the productId and quantity (which will be negative, since the inventory will decrease after the sale).

I would like to run a group by/ sum aggregate query on the Inventory table with Parse Cloud Code that outputs a dictionary containing unique productIds as the keys and the sum of the quantity column for those Ids as the values.

I have seen a number of old posts saying that Parse does not do this, but then more recent posts refer to Cloud Code such as averageStart in the Cloud Code Guide: https://parse.com/docs/cloud_code_guide

However, it seems that Parse.Query used in averageStars has a maximum limit of 1000 records. Thus, when I sum the quantity column, I am only doing so on 1000 records rather than the whole table. Is there a way that I can compute the group by/ sum across all the records in the inventory table?

---

For example:

Inventory Table

productId quantity

Record 1: AAAAA 50

Record 2: BBBBB 40

Record 3: AAAAA -5

Record 4: BBBBB -2

Record 5: AAAAA 10

Record 6: AAAAA -7

Output dictionary: {AAAAA: 48, BBBBB: 38}

解决方案

You can use Parse.Query.each(). It has no limit. If your class has too many entries it will timeout though.

See docs

e.g.:

var totalQuantity = 0;
var inventoryQuery = new Parse.Query("Inventory");
inventoryQuery.each(
    function(result){
        totalQuantity += result.get("quantity");
    }, {
        success: function() {
            // looped through everything
        },
        error: function(error) {
            // error is an instance of Parse.Error.
        }
    });
});

If it times out, you have to build something like this.

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