将 CSV 行转换为 Javascript 个对象

Question

我有一个简单的 csv 文件

people.csv:

fname, lname, uid, phone, address
John, Doe, 1, 444-555-6666, 34 dead rd
Jane, Doe, 2, 555-444-7777, 24 dead rd
Jimmy, James, 3, 111-222-3333, 60 alive way

我想做的是获取 CSV 的每一行，将其转换为 JavaScript 对象，将它们存储到数组中，然后将数组转换为 JSON 对象。

server.js:

var http = require('http');
var url  = require('url');
var fs = require('fs');

var args = process.argv;
var type = args[2] || 'text';
var arr = []; 
var bufferString; 

function csvHandler(req, res){
  fs.readFile('people.csv',function (err,data) {

  if (err) {
    return console.log(err);
  }

  //Convert and store csv information into a buffer. 
  bufferString = data.toString(); 

  //Store information for each individual person in an array index. Split it by every newline in the csv file. 
  arr = bufferString.split('\n'); 
  console.log(arr); 

  for (i = 0; i < arr.length; i++) { 
    JSON.stringify(arr[i]); 
  }

  JSON.parse(arr); 
  res.send(arr);  
});
}

//More code ommitted

我的问题是，当我在 bufferString 上调用 .split('\n') 方法时，我是否真的将 CSV 行转换为 Javascript 对象，或者是否有其他方法？

Answer 1

通过这样做：

arr = bufferString.split('\n');

您将拥有一个包含所有行的数组作为字符串

["fname, lname, uid, phone, address","John, Doe, 1, 444-555-6666, 34 dead rd",...]

您必须使用 .split(',') 用逗号再次分隔它，然后将 headers 分开并将其推入 Javascript Object:

var jsonObj = [];
var headers = arr[0].split(',');
for(var i = 1; i < arr.length; i++) {
  var data = arr[i].split(',');
  var obj = {};
  for(var j = 0; j < data.length; j++) {
     obj[headers[j].trim()] = data[j].trim();
  }
  jsonObj.push(obj);
}
JSON.stringify(jsonObj);

那么你会得到这样的object：

[{"fname":"John",
  "lname":"Doe",
  "uid":"1",
  "phone":"444-555-6666",
  "address":"34 dead rd"
 }, ... }]

看到这个FIDDLE

Answer 2

您可以尝试使用 MVC Razor，

<script type="text/javascript">
    MyNamespace.myConfig = @Html.Raw(Json.Encode(new MyConfigObject()));
</script>

Json.Encode会将初始化对象序列化为JSON格式。然后 Html.Raw 将阻止它将引号编码为 ".

此处完整example

Answer 3

您可以使用 lodash（或下划线）来帮助解决这个问题。

var objects = _.map(arr, function(item){return item.split(',');});
var headers = objects[0];
objects.splice(0, 1); // remove the header line
populatedObject = [];
objects.forEach(function(item){
   var obj = _.zipObject(headers, item);
   populatedObject.push(obj);
});

.zipObject 方法会将每个 header 与 items 数组中的每个值匹配并生成一个 object。

Answer 4

使用ES6/ES7和一些函数式编程指南：

所有变量都是const（不变性）
使用map/reduce代替while/for
所有功能都是箭头
无依赖关系

// Split data into lines and separate headers from actual data
// using Array spread operator
const [headerLine, ...lines] = data.split('\n');

// Split headers line into an array
// `valueSeparator` may come from some kind of argument
// You may want to transform header strings into something more
// usable, like `camelCase` or `lowercase-space-to-dash`
const valueSeparator = '\t';
const headers = headerLine.split(valueSeparator);

// Create objects from parsing lines
// There will be as much objects as lines
const objects = lines
  .map( (line, index) =>
    line
      // Split line with value separators
      .split(valueSeparator)

      // Reduce values array into an object like: { [header]: value }
      // https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/reduce
      .reduce(

        // Reducer callback 
        (object, value, index) => ({
          ...object,
          [ headers[index] ]: value,
        }),

        // Initial value (empty JS object)
        {}
      )
  );

console.log("Objects:", objects);

对于使用 , 作为分隔符和引号字符串值的 CSV 文件，您可以使用此版本：

// Split data into lines and separate headers from actual data
// using Array spread operator
const [headerLine, ...lines] = data.split('\n');

// Use common line separator, which parses each line as the contents of a JSON array
const parseLine = (line) => JSON.parse(`[${line}]`);

// Split headers line into an array
const headers = parseLine(headerLine);

// Create objects from parsing lines
// There will be as much objects as lines
const objects = lines
  .map( (line, index) =>

    // Split line with JSON
    parseLine(line)

      // Reduce values array into an object like: { [header]: value } 
      .reduce( 
        (object, value, index) => ({
          ...object,
          [ headers[index] ]: value,
        }),
        {}
      ) 
  );

return objects;

注意：对于大文件，最好使用流、生成器、迭代器等

Answer 5

如果您已经有一个数组并希望 csv header（第一行）成为 object 的属性。

，那么这是一个解决方案


const csvArrayToObj = (csvData) => {
  return csvData
    .map((csvLine, csvIndex) => {
      if (csvIndex === 0 || !csvLine.length) return null; // skip header and empty lines
      return csvLine.reduce((a, v, i) => ({ ...a, [csvData[0][i]]: v }), {});
    })
    .filter((filter) => !!filter); //filter empty lines
};

const csvArray = [
  ['name', 'age'],
  ['John Doe', 20],
  ['Jane Doe', 30],
];

csvArrayToObj(csvArray);

// output
[
    {
        "name": "John Doe",
        "age": 20
    },
    {
        "name": "Jane Doe",
        "age": 30
    }
]

将 CSV 行转换为 Javascript 个对象

convert CSV lines into Javascript objects

javascript

csv

node.js