#CSV2JSON
All you need nodejs csv to json converter. Support big json data, CLI, server. can be easily plugged and used in other nodejs app.
##Menu
GitHub: https://github.com/Keyang/node-csvtojson
##Installation
npm install -g csvtojson
##Features
- Powerful library for you nodejs applications processing csv data.
- Extremly straight forward
- Multiple input support: CSV File, Readable Stream, CSV String etc.
- Highly extendible with your own rules and parsers for outputs.
- Multiple interfaces (webservice, command line)
##Usage
###Command Line Tools
csvtojson [ CSVFilePath | StartServer] [port]
Example
csvtojson ./myCSVFile
Or use pipe:
cat myCSVFile | csvtojson
To start a webserver
csvtojson startserver [port]
Default port number is 8801.
WebService
After webserve being initialised, it is able to use http post with CSV data as body.
For example, we start web server with default configuration:
csvtojson startserver
And then we use curl to perform a web request:
curl -X POST -d "date,*json*employee.name,*json*employee.age,*json*employee.number,*array*address,*array*address,*jsonarray*employee.key,*jsonarray*employee.key,*omit*id
2012-02-12,Eric,31,51234,Dunno Street,Kilkeny Road,key1,key2,2
2012-03-06,Ted,28,51289,Cambridge Road,Tormore,key3,key4,4" http://127.0.0.1:8801/parseCSV
API
Use csvtojson library to your own project.
Import csvtojson to your package.json or install through npm:
npm install csvtojson
Quick Start
The core of the tool is Converter class. It is based on node-csv library (version 0.3.6). Therefore it has all features of node-csv. To start a parse, simply use following code:
var Converter=require("csvtojson").core.Converter;
var csvFileName="./myCSVFile";
var csvConverter=new Converter();
csvConverter.on("end_parsed",function(jsonObj){
console.log(jsonObj);
});
csvConverter.from(csvFileName);
Parser
CSVTOJSON allows adding customised parsers which concentrating on what to parse and how to parse.
It is the main power of the tool that developer only needs to concentrate on how to deal with the data and other concerns like streaming, memory, web, cli etc are done automatically.
How to add a customised parser:
var parserMgr=require("csvtojson").core.parserMgr;
parserMgr.addParser("myParserName",/^\*parserRegExp\*/,function (params){
var columnTitle=params.head;
var fieldName=columnTitle.replace(this.regExp, "");
params.resultRow[fieldName]="Hello my parser"+params.item;
});
parserMgr's addParser function take three parameters:
-
parser name: the name of your parser. It should be unique.
-
Regular Expression: It is used to test if a column of CSV data is using this parser. In the example above any column's first row starting with parserRegExp will be using it.
-
Parse function call back: It is where the parse happens. The converter works row by row and therefore the function will be called each time needs to parse a cell in CSV data.
The parameter of Parse function is a JSON object. It contains following fields:
head: The column's first row's data. It generally contains field information. e.g. arrayitems
item: The data inside current cell. e.g. item1
itemIndex: the index of current cell of a row. e.g. 0
rawRow: the reference of current row in array format. e.g. ["item1", 23 ,"hello"]
resultRow: the reference of result row in JSON format. e.g. {"name":"Joe"}
rowIndex: the index of current row in CSV data. start from 1 since 0 is the head. e.g. 1
resultObject: the reference of result object in JSON format. It always has a field called csvRows which is in Array format. It changes as parsing going on. e.g.
{
"csvRows":[
{
"itemName":"item1",
"number":10
},
{
"itemName":"item2",
"number":4
}
]
}
WebServer
It is able to start the web server through code.
var webServer=require("csvtojson").interfaces.web;
var expressApp=webServer.startWebServer({
"port":"8801",
"urlPath":"/parseCSV"
});
It will return an expressjs Application. You can add your own web app content there.
If you already have an express application, simply use following code to extend your current application
var webServer=require("csvtojson").interfaces.web;
webServer.applyWebServer(app, postURL);
Events
Following events are used for Converter class:
- end_parsed: It is emitted when parsing finished. the callback function will contain the JSON object
- record_parsed: it is emitted each time a row has been parsed. The callback function has following parameters: result row JSON object reference, Original row array object reference, row index
To subscribe the event:
var Converter=require("csvtojson").core.Converter;
csvConverter.on("end_parsed",function(jsonObj){
console.log(jsonObj);
});
csvConverter.on("record_parsed",function(resultRow,rawRow,rowIndex){
console.log(resultRow);
});
Default Parsers
There are default parsers in the library they are
Array: For columns head start with "array" e.g. "arrayfieldName", this parser will combine cells data with same fieldName to one Array.
Nested JSON: For columns head start with "json" e.g. "jsonmy.nested.json.structure", this parser will create nested nested JSON structure: my.nested.json
Nested JSON Array: For columns head start with "jsonarray" e.g. "jsonarraymy.items", this parser will create structure like my.items[].
Omitted column: For columns head start with "omit" e.g. "omitid", the parser will omit the column's data.
####Example:
Original data:
date,*json*employee.name,*json*employee.age,*json*employee.number,*array*address,*array*address,*jsonarray*employee.key,*jsonarray*employee.key,*omit*id
2012-02-12,Eric,31,51234,Dunno Street,Kilkeny Road,key1,key2,2
2012-03-06,Ted,28,51289,Cambridge Road,Tormore,key3,key4,4
Output data:
{
"csvRows": [
{
"date": "2012-02-12",
"employee": {
"name": "Eric",
"age": "31",
"number": "51234",
"key": [
"key1",
"key2"
]
},
"address": [
"Dunno Street",
"Kilkeny Road"
]
},
{
"date": "2012-03-06",
"employee": {
"name": "Ted",
"age": "28",
"number": "51289",
"key": [
"key3",
"key4"
]
},
"address": [
"Cambridge Road",
"Tormore"
]
}
]
}
Big CSV File
csvtojson library was designed to accept big csv file converting. To avoid memory consumption, it is recommending to use read stream and write stream.
var Converter=require("csvtojson").core.Converter;
var csvConverter=new Converter(false);
var readStream=require("fs").createReadStream("inputData.csv");
var writeStream=require("fs").createWriteStream("outpuData.json");
var started=false;
csvConverter.on("record_parsed",function(rowJSON){
if (started){
writeStream.write(",\n");
}
writeStream.write(JSON.stringify(rowJSON));
if (started==false){
started=true;
}
});
writeStream.write("[\n");
csvConverter.on("end_parsed",function(){
writeStream.write("\n]");
});
csvConverter.from(readStream);
The Converter constructor was passed in a "false" parameter which will tell the constructor not to combine the final result which would take simlar memory as the file size. The output is constructed line by line through writable stream object.