Transform a stream of JSON into a stream of Line Delimited JSON
npm install jsonl> Transform a stream of JSON into a stream of Line Delimited JSON
sh
$ npm install --save jsonl
`Use
$3
`js
var fs = require("fs")
var jsonl = require("jsonl")fs.createReadStream("./in.json")
.pipe(jsonl())
.pipe(fs.createWriteStream("./out.json"))
`
#### in.json
`json
[{"test":"value"},{"test":"value"},{"test":"value"},{"test":"value"}]
`
#### out.json
`json
{"test":"value"}
{"test":"value"}
{"test":"value"}
{"test":"value"}`$3
`js
var fs = require("fs")
var jsonl = require("jsonl")
var through = require("through2")
var stream = through.obj()stream.pipe(jsonl({toBufferStream:true}))
.pipe(fs.createWriteStream("./out.json"))
stream.push({test:"value"})
stream.push({test:"value"})
stream.push({test:"value"})
stream.push({test:"value"})
stream.end()
`
#### out.json
`json
{"test":"value"}
{"test":"value"}
{"test":"value"}
{"test":"value"}`$3
To get the results you expect, you will likely need to know the structure of your incoming data. You may have to pass a depth property, which corresponds to the layer of the property in a serialized, nested JSON object.By default, jsonl will use a depth of 1 when reading data from a Buffer stream (expecting objects to be nested in an array), and a depth of 0 from a stream in object mode.
`js
/0/[
/1/ {
/2/ test: "value"
/1/ },
/1/ {
/2/ test: "value"
/1/ }
/0/]
`$3
To filter the incoming data based on properties, you can select specific fields to be plucked out of the incoming object.\* You will need to specify a
depth property for the nested level of the property.
`js
var fs = require("fs")
var jsonl = require("jsonl")fs.createReadStream("./in.json")
.pipe(jsonl({pluck:["category"], depth:2}))
.pipe(fs.createWriteStream("./out.json"))
`
#### in.json
`json
[{"category": "cactus heights", "question":"?", "answer": "!"},{"category": "giraffe shoe sizes", "question":"?", "answer": "!"}]
`
#### out.json
`json
{"category":"cactus heights"}
{"category":"giraffe shoe sizes"}`API
$3
#### opts.depth
- Type:
Number (default: 1)The depth of the objects in the incoming data to pluck out. This is what you want for an array of objects, such as:
`json
[{"this":"that"},{"this":"that"}]
`#### opts.objectMode
- Type:
Boolean (default: false)Convert data into an object stream.
#### opts.pluck
- Type:
Array|String (default: [])Only return select properties from JSON objects.
#### opts.separator
- Type:
String (default: \n)String to separate object data with.
#### opts.toBufferStream
- Type:
Boolean (default: false)Set this to true when you have an object stream that you would like converted to a stream of line delimited JSON buffers.
If set, this defaults
opts.depth to 0`, but can still be overridden.MIT © Stephen Sawchuk