Question

我正在使用node-postgres检索LEFT OUTER连接查询的结果：

SELECT S.SEASON_ID, S.SEASON_NAME, I.ITEM_NAME, I.NOTE FROM T_SEASON S LEFT OUTER JOIN T_ITEM I ON S.SEASON_ID = I.SEASON_ID;

结果集将如下所示：

[
 {
   season_id:1, 
   season_name: "season 1", 
   item_name:"item1", 
   item_note: "text"
 }, 
 {
   season_id:1, 
   season_name: "season 1", 
   item_name:"item2", 
   item_note: "text"
 }, 
 {
   season_id:2, 
   season_name: "season 2", 
   item_name:"item3", 
   item_note: "text"
 }
]

我需要做的是将其分解为“季节”对象数组，如下所示：

[
 {
   seasonId: 1, 
   season_name: "season 1", 
   items: [
      {item_name: "item1", item_note: "text"},
      {item_name: "item2", item_note: "text"}
   ]
 }, 
 {
   seasonId: 2, 
   season_name: "season2", 
   items: [
      {item_name: "item3", item_note: "text"}
   ]
 }
]

按顺序，“项目”是季节对象的子级集合。

我正在寻找最简单的方法。 Lodash对我可用。

Answer 1

您可以使用reduce

基于season_id创建一个密钥。检查该键是否存在，而不是在该特定键的项目中推送值，而不是创建具有适当值的新键。最后，只需从对象中取出值即可获得所需的输出。

let data = [{season_id:1, season_name: "season 1", item_name:"item1", item_note: "text"}, {season_id:1, season_name: "season 1", item_name:"item2", item_note: "text"}, {season_id:2, season_name: "season 2", item_name:"item3", item_note: "text"}]

let output = data.reduce(( op, {season_id, item_name, item_note, season_name }) => {
  if(op[season_id]){
    op[season_id].items.push({item_name,item_note})
  } else {
    op[season_id] = {
      season_id,
      season_name,
      items: [{item_name,item_note}]
    }
  }
  return op
},{})

console.log(Object.values(output))

LEFT OUTER JOIN查询结果的Javascript转换

1 个答案: