如何分隔每个JSON对象并将它们分组为JavaScript中的数组? [英] How could I separate each JSON object and group them to an array in JavaScript?

问题描述

来自multer.js的req.files示例

example of req.files from multer.js

[
    {
        fieldname: files0,
        originalname: 'Screenshot from 2020-05-23 01-52-30.png',
        encoding: '7bit',
        mimetype: 'image/png',
        destination: 'public/uploads/projects/0a480789-eb14-4fe4-bb89-44aa741efe33/proposals/chma00000133',
        filename: '1606822252923_Screenshot from 2020-05-23 01-52-30.png',
        path: 'public/uploads/projects/0a480789-eb14-4fe4-bb89-44aa741efe33/proposals/chma00000133/1606822252923_Screenshot from 2020-05-23 01-52-30.png',
        size: 172092
      },
      {
        fieldname: files0,
        originalname: 'Screenshot from 2020-05-22 08-44-05.png',
        encoding: '7bit',
        mimetype: 'image/png',
        destination: 'public/uploads/projects/0a480789-eb14-4fe4-bb89-44aa741efe33/proposals/chma00000133',
        filename: '1606822252925_Screenshot from 2020-05-22 08-44-05.png',
        path: 'public/uploads/projects/0a480789-eb14-4fe4-bb89-44aa741efe33/proposals/chma00000133/1606822252925_Screenshot from 2020-05-22 08-44-05.png',
        size: 440592
      },
      {
        fieldname: files1,
        originalname: 'Screenshot from 2020-05-30 11-36-42.png',
        encoding: '7bit',
        mimetype: 'image/png',
        destination: 'public/uploads/projects/0a480789-eb14-4fe4-bb89-44aa741efe33/proposals/chma00000133',
        filename: '1606822252930_Screenshot from 2020-05-30 11-36-42.png',
        path: 'public/uploads/projects/0a480789-eb14-4fe4-bb89-44aa741efe33/proposals/chma00000133/1606822252930_Screenshot from 2020-05-30 11-36-42.png',
        size: 477511
      },
      {
        fieldname: files1,
        originalname: 'Screenshot from 2020-05-30 11-36-36.png',
        encoding: '7bit',
        mimetype: 'image/png',
        destination: 'public/uploads/projects/0a480789-eb14-4fe4-bb89-44aa741efe33/proposals/chma00000133',
        filename: '1606822252931_Screenshot from 2020-05-30 11-36-36.png',
        path: 'public/uploads/projects/0a480789-eb14-4fe4-bb89-44aa741efe33/proposals/chma00000133/1606822252931_Screenshot from 2020-05-30 11-36-36.png',
        size: 223362
      },
      {
        fieldname: files1,
        originalname: 'Screenshot from 2020-05-30 11-36-31.png',
        encoding: '7bit',
        mimetype: 'image/png',
        destination: 'public/uploads/projects/0a480789-eb14-4fe4-bb89-44aa741efe33/proposals/chma00000133',
        filename: '1606822252932_Screenshot from 2020-05-30 11-36-31.png',
        path: 'public/uploads/projects/0a480789-eb14-4fe4-bb89-44aa741efe33/proposals/chma00000133/1606822252932_Screenshot from 2020-05-30 11-36-31.png',
        size: 260419
      }
]

我想用其字段名对每个JSON对象进行动态分组，并将它们存储在对象数组中，同时使用它们的字段名编号作为它们的数组索引.

I want to dynamically group each JSON objects with their fieldname and store them in an array of objects while using their fieldname number as their array index.

根据用户的输入，组可以在0到9之间.

The groups can be between 0 to 9, depending on the user input.

我希望得到的结果是类似的

The result I'm hoping for is something like

someArr = [

    [
        {
            fieldname: files0
            originalname: somevalue,
            ...
            size: some value
        },
        {
            fieldname: files0,
            originalname: somevalue,
            ...
            size: some value
        },
    ]
        ,
    [
        
        {
            fieldname: files1,
            originalname: somevalue,
            ...
            size: some value
        },
        {
            fieldname: files1,
            originalname: somevalue,
            ...
            size: some value
        },
        {
            fieldname: files1,
            originalname: somevalue,
            ...
            size: some value
        },
    ]
    ...
    
]

，如果存在，则someArr [9]将返回

and if it exists, someArr[9] would return

[

    {
        fieldname: files9,
        originalname: somevalue,
        ...
        size: some value
    },
    {
        fieldname: files9,
        originalname: somevalue,
        ...
        size: some value
    },
]

我尝试过的是首先从字段名称中解析整数，然后将其重新分配为它们的值，以便使用for循环更好地进行排序

What I've tried was first parse integers from fieldnames and reassign them as their values for better sorting with for-loops

Object.keys(req.files).forEach((key) => {
  const thisFile = req.files[key];
  const thisFileGroup = parseInt(thisFile.fieldname.match(/\d/g).join(''), 10); 
  // rename fieldname from files0, files1 ... to 0 , 1 ....
  req.files[key].fieldname = thisFileGroup;
});

但是从这里，我无法找到将此元素(thisFile)推送到的位置，因为我无法在较高范围预先声明每个数组，因为它们也需要动态创建.

But from here, I can't find where to push this element(thisFile) to, since I cannot predeclare each arrays at the upper scope since they also need to be created dynamically.

推荐答案

我会使用

const data = [ 
{ fieldname: 'files0', originalname: 'Screenshot from 2020-05-23 01-52-30.png', },
{ fieldname: 'files0', originalname: 'Screenshot from 2020-05-22 08-44-05.png', },
{ fieldname: 'files1', originalname: 'Screenshot from 2020-05-30 11-36-42.png', },
{ fieldname: 'files1', originalname: 'Screenshot from 2020-05-30 11-36-36.png', },
{ fieldname: 'files1', originalname: 'Screenshot from 2020-05-30 11-36-31.png', }],
arr = data.reduce((acc, cur) => {
  const idx = cur.fieldname.replace("files",""); // get 0, 1
  if (acc[idx]) acc[idx].push(cur); // if already there, just push
  else acc[idx] = [cur];            // otherwise initialise
  return acc;
},[]) 

console.log(arr)

注意:根据用户的输入，组的范围可以在0到9之间.

我假设没有孔，因为这可能会导致数组稀疏

I assume there are no holes since that could result in a sparse array so

data = [ 
     { fieldname : 'files0' },
     { fieldname : 'files0' },
     { fieldname : 'files3' },
     { fieldname : 'files3' },
 }

将创建一个数组

[
  [ { fieldname : 'files0' }, { fieldname : 'files0' } ],
  null,
  null,
  [ { fieldname : 'files3' }, { fieldname : 'files3' } ],
]

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