如何在Javascript中解析CSV [英] How to Approach Parsing CSV in Javascript

问题描述

（我的第一篇文章，如有任何错误，我深表歉意）

(My first post, I apologise for any mistakes)

我正在处理CSV文件中的一小部分数据，我需要阅读，处理，然后导出为文本文件。

I'm working with a small set of data in CSV files, which I need to read, process, and then export as a text file.

CSV数据的格式为：

The format of the CSV data is:

REGO,STATUS,SHIFT,LOCATION,LOADED
CCA4110,StatusON,5:43,Brisbane,1
CCA4112,StatusON,5:44,Syndey,0
CCA4118,StatusON,6:11,Melbourne,1

我希望能够标题行，并检查

I want to be able to take each line after the header row, and check

a）如果 LOADED值等于0或1（如果为1，则跳至下一行）。

a) if the 'LOADED' value equals 0 or 1 (skip to next row if 1).

b）如果 LOADED为0，则检查 REGO值是否与 REGO值的预定义列表匹配。

b) If 'LOADED' is 0, then check if the 'REGO' value matches a pre-defined list of 'REGO' values.

c）如果匹配，请更改 SHIFT时间。

c) If a match, change the 'SHIFT' time.

d）如果不匹配，请移至下一行。

d) If no match, move on to next row.

之后，我要导出所有内容行中只有'REGO'和'SHIFT'值的样子：

After that, I want to export all of the rows, with only the 'REGO' and 'SHIFT' values, to look like:

CCA4110,5:43
CCA4112,5:33
...

因为这有点复杂对我来说，我很难想象解决此问题的最佳方法。我想知道是否有人可以帮助我考虑一下这种方式，而不仅是一起破解一堆嵌套的循环。

Because this feels a little complex to me, I'm having trouble visualising the best way to approach this problem. I was wondering if someone could help me think about this in a way that isn't just hacking together a dozen nested for loops.

非常感谢，

利亚姆

编辑：有关检查多个条件的问题：

说我有两个CSV文件：

Say I have two CSV files:

List_to_Change.csv

REGO,STATUS,SHIFT,LOCATION,LOADED       
CCA2420,StatusOn,11:24,BRISBANE,1
CCA2744,StatusOn,4:00,SYDNEY,1
CCA2009,StatusOn,4:00,MELBOURNE,0

List_to_Compare.csv

REGO,CORRECT_SHIFT
CCA2420,6:00
CCA2660,6:00
CCA2009,5:30

一种算法：

1。。检查 List_to_Check.csv LOADED列中的值

1. Check value in 'List_to_Check.csv' 'LOADED' column

A。如果值等于 0，请转到步骤2。

A. If value equals '0' go to step 2.

B。如果值等于 1，请跳过此行并转到下一个。

B. If value equals '1' skip this row and go to next.

2。。检查 List_to_Check.csv中的 REGO值是否显示在 List_to_Compare.csv中。

2. Check if 'REGO' value in 'List_to_Check.csv' shows up in 'List_to_Compare.csv'

A。如果是，则转到步骤3。

A. If true go to step 3.

B。如果为false，则跳过此行并转到下一步。

B. If false skip this row and go to next.

3。。将 List_to_Change.csv中的 SHIFT值更改为 List_to_Compare.csv'

3. Change 'SHIFT' value in 'List_to_Change.csv' with value shown in 'List_to_Compare.csv'

4。字符串化已更改的每一行并导出到文本文件。

4. Stringify each row that was changed and export to text file.

推荐答案

我的建议是将工作流程分为三个步骤：

My advice would be to split the work flow in to three steps:

1. 将所有行解析为javascript对象


2. 对对象数组执行逻辑


3. 将对象字符串化为CSV

// This creates an object based on an order of columns:
const Entry = ([rego, status, shift, location, loaded]) =>
  ({ rego, status, shift, location, loaded });
  
// Which entries are we interested in?
const shouldHandleEntry = ({ loaded }) => loaded === "1";

// How do we update those entries?
const updateEntry = entry => ({
  ...entry,
  shift: ["CCA4118"].includes(entry.rego)
    ? "5:33"
    : entry.shift
});

// What do we export?
const exportEntry = ({ rego, shift }) => `${rego},${shift}`;

// Chain the steps to create a new table:
console.log(
  csvBody(getCSV())
    .map(Entry)
    .filter(shouldHandleEntry)
    .map(updateEntry)
    .map(exportEntry)
    .join("\n")
)


// (This needs work if you're using it for production code)
function csvBody(csvString) {
  return csvString
    .split("\n")
    .map(line => line.trim().split(","))
    .slice(1);
};

function getCSV() { return `REGO,STATUS,SHIFT,LOCATION,LOADED
CCA4110,StatusON,5:43,Brisbane,1
CCA4112,StatusON,5:44,Sydney,0
CCA4118,StatusON,6:11,Melbourne,1`; }

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