json2csv

Converts json into csv with column titles and proper line endings. Can be used as a module and from the command line.

How to use

Install

$ npm install json2csv --save

Include the module and run

var json2csv = require('json2csv');
var fields = ['field1', 'field2', 'field3'];

json2csv({ data: myData, fields: fields }, function(err, csv) {
  if (err) console.log(err);
  console.log(csv);
});

or use it from the CLI.

Features

• Uses proper line endings on various operating systems
• Handles double quotes
• Allows custom column selection
• Allows specifying nested properties
• Reads column selection from file
• Pretty writing to stdout
• Supports optional custom delimiters
• Supports optional custom eol value
• Supports optional custom quotation marks
• Not create CSV column title by passing hasCSVColumnTitle: false, into params.
• If field is not exist in object then the field value in CSV will be empty.

Use as a module

Available Options

• options - Required; Options hash.
  • data - Required; Array of JSON objects.
  • fields - Array of Objects/Strings. Defaults to toplevel JSON attributes. See example below.
  • fieldNames Array of Strings, names for the fields at the same indexes. Must be the same length as fields array. (Optional. Maintained for backwards compatibility. Use fields config object for more features)
  • del - String, delimiter of columns. Defaults to , if not specified.
  • defaultValue - String, default value to use when missing data. Defaults to <empty> if not specified. (Overridden by fields[].default)
  • quotes - String, quotes around cell values and column names. Defaults to " if not specified.
  • doubleQuotes - String, the value to replace double quotes in strings. Defaults to 3xquotes (for example """) if not specified.
  • hasCSVColumnTitle - Boolean, determines whether or not CSV file will contain a title column. Defaults to true if not specified.
  • eol - String, it gets added to each row of data. Defaults to `` if not specified.
  • newLine - String, overrides the default OS line ending (i.e. \n on Unix and \r\n on Windows).
  • flatten - Boolean, flattens nested JSON using flat. Defaults to false.
• callback - Required; function (error, csvString) {}. To create a promise, you can use var toCSV = Bluebird.promisify(json2csv), see Bluebird docs.

Example fields option

{
  fields: [
    // Supports label -> simple path
    {
      label: 'some label', // (optional, column will be labeled 'path.to.something' if not defined)
      value: 'path.to.something', // data.path.to.something
      default: 'NULL' // default if value is not found (optional, overrides `defaultValue` for column)
    },

    // Supports label -> derived value
    {
      label: 'some label', // Supports duplicate labels (required, else your column will be labeled [function])
      value: function(row) {
        return row.path1 + row.path2;
      },
      default: 'NULL' // default if value fn returns falsy
    },

    // Support pathname -> pathvalue
    'simplepath' // equivalent to {value:'simplepath'}
    'path.to.value' // also equivalent to {label:'path.to.value', value:'path.to.value'}
  ]
}

Example 1

var json2csv = require('json2csv');
var fs = require('fs');
var fields = ['car', 'price', 'color'];
var myCars = [
  {
    "car": "Audi",
    "price": 40000,
    "color": "blue"
  }, {
    "car": "BMW",
    "price": 35000,
    "color": "black"
  }, {
    "car": "Porsche",
    "price": 60000,
    "color": "green"
  }
];

json2csv({ data: myCars, fields: fields }, function(err, csv) {
  if (err) console.log(err);
  fs.writeFile('file.csv', csv, function(err) {
    if (err) throw err;
    console.log('file saved');
  });
});

The content of the "file.csv" should be

car, price, color
"Audi", 40000, "blue"
"BMW", 35000, "black"
"Porsche", 60000, "green"

Example 2

Similarly to mongoexport you can choose which fields to export

var json2csv = require('json2csv');
var fields = ['car', 'color'];

json2csv({ data: myCars, fields: fields }, function(err, csv) {
  if (err) console.log(err);
  console.log(csv);
});

Results in

car, color
"Audi", "blue"
"BMW", "black"
"Porsche", "green"

Example 3

Use a custom delimiter to create tsv files. Add it as the value of the del property on the parameters:

var json2csv = require('json2csv');
var fields = ['car', 'price', 'color'];

json2csv({ data: myCars, fields: fields, del: '\t' }, function(err, tsv) {
  if (err) console.log(err);
  console.log(tsv);
});

Will output:

car price color
"Audi"  10000 "blue"
"BMW" 15000 "red"
"Mercedes"  20000 "yellow"
"Porsche" 30000 "green"

If no delimiter is specified, the default , is used

Example 4

You can choose custom column names for the exported file.

var json2csv = require('json2csv');
var fields = ['car', 'price'];
var fieldNames = ['Car Name', 'Price USD'];

json2csv({ data: myCars, fields: fields, fieldNames: fieldNames }, function(err, csv) {
  if (err) console.log(err);
  console.log(csv);
});

Example 5

You can choose custom quotation marks.

var json2csv = require('json2csv');
var fields = ['car', 'price'];
var fieldNames = ['Car Name', 'Price USD'];
var opts = {
  data: myCars,
  fields: fields,
  fieldNames: fieldNames,
  quotes: ''
};

json2csv(opts, function(err, csv) {
  if (err) console.log(err);
  console.log(csv);
});

Results in

Car Name, Price USD
Audi, 10000
BMW, 15000
Porsche, 30000

Example 6

You can also specify nested properties using dot notation.

var json2csv = require('json2csv');
var fs = require('fs');
var fields = ['car.make', 'car.model', 'price', 'color'];
var myCars = [
  {
    "car": {"make": "Audi", "model": "A3"},
    "price": 40000,
    "color": "blue"
  }, {
    "car": {"make": "BMW", "model": "F20"},
    "price": 35000,
    "color": "black"
  }, {
    "car": {"make": "Porsche", "model": "9PA AF1"},
    "price": 60000,
    "color": "green"
  }
];

json2csv({ data: myCars, fields: fields }, function(err, csv) {
  if (err) console.log(err);
  fs.writeFile('file.csv', csv, function(err) {
    if (err) throw err;
    console.log('file saved');
  });
});

The content of the "file.csv" should be

car.make, car.model, price, color
"Audi", "A3", 40000, "blue"
"BMW", "F20", 35000, "black"
"Porsche", "9PA AF1", 60000, "green"

Command Line Interface

json2csv can also be called from the command line if installed with -g.

Usage: json2csv [options]

  Options:

    -h, --help                   output usage information
    -V, --version                output the version number
    -i, --input <input>          Path and name of the incoming json file.
    -o, --output [output]        Path and name of the resulting csv file. Defaults to console.
    -f, --fields <fields>        Specify the fields to convert.
    -l, --fieldList [list]       Specify a file with a list of fields to include. One field per line.
    -d, --delimiter [delimiter]  Specify a delimiter other than the default comma to use.
    -e, --eol [value]            Specify an EOL value after each row.
    -z, --newLine [value]        Specify an new line value for separating rows.
    -q, --quote [value]          Specify an alternate quote value.
    -n, --no-header              Disable the column name header
    -F, --flatten                Flatten nested objects
    -L, --ldjson                 Treat the input as Line-Delimited JSON.
    -p, --pretty                 Use only when printing to console. Logs output in pretty tables.

An input file -i and fields -f are required. If no output -o is specified the result is logged to the console. Use -p to show the result in a beautiful table inside the console.

CLI examples

Input file and specify fields

$ json2csv -i input.json -f carModel,price,color

carModel,price,color
"Audi",10000,"blue"
"BMW",15000,"red"
"Mercedes",20000,"yellow"
"Porsche",30000,"green"

Input file, specify fields and use pretty logging

$ json2csv -i input.json -f carModel,price,color -p

Input file, specify fields and write to file

$ json2csv -i input.json -f carModel,price,color -o out.csv

Content of out.csv is

carModel,price,color
"Audi",10000,"blue"
"BMW",15000,"red"
"Mercedes",20000,"yellow"
"Porsche",30000,"green"

Input file, use field list and write to file

The file fieldList contains

carModel
price
color

Use the following command with the -l flag

$ json2csv -i input.json -l fieldList -o out.csv

Content of out.csv is

carModel,price,color
"Audi",10000,"blue"
"BMW",15000,"red"
"Mercedes",20000,"yellow"
"Porsche",30000,"green"

Read from stdin

$ json2csv -f price
[{"price":1000},{"price":2000}]

Hit Enter and afterwards CTRL + D to end reading from stdin. The terminal should show

price
1000
2000

Appending to existing CSV

Sometimes you want to add some additional rows with the same columns. This is how you can do that.

# Initial creation of csv with headings
$ json2csv -i test.json -f name,version > test.csv
# Append additional rows
$ json2csv -i test.json -f name,version --no-header >> test.csv

Testing

Run

$ npm test

Contributors

Install require packages for development run following command under json2csv dir.

Run

$ npm install

Could you please make sure code is formatted and test passed before submit Pull Requests?

See Testing and Formatting json2csv above.

But I want streams!

Check out my other module json2csv-stream. It transforms an incoming stream containing json data into an outgoing csv stream.

Similar Projects

• Papa Parse

License

See LICENSE.md.