问题描述
一种从上到下逐行读取文件的简单方法:
const { once } = require('events');
const { createReadStream } = require('fs');
const { createInterface } = require('readline');
let storeProducts = async () => {
try {
const filename = path.join(__dirname,"bulk-101638307937.jsonl");
const rl = createInterface({
input: createReadStream(filename),crlfDelay: Infinity
});
rl.on('line',(line) => {
// Process the line.
console.log({line: JSON.parse(line)});
});
await once(rl,'close');
console.log('File processed.');
} catch (err) {
console.error(err);
}
}
这很好。但是我需要逐行向后读取一个大的jsonl文件。我已经尝试过Draw a concave polygon in OpenGL。它向后读取文件,但不是逐行读取。任何帮助将不胜感激。
一个示例jsonl
{"id": 1,"product": "A"}
{"variant_id": 1,"product": "A"}
{"id": 2,"product": "B"}
{"variant_id": 2,"product": "B"}
{"id": 3,"product": "C"}
{"variant_id": 3,"product": "C"}
{"id": 4,"product": "D"}
{"variant_id": 4,"product": "D"}
{"variant_id": 5,"product": "D"}
解决方法
fs-reverse库应该可以解决问题:
const fsR = require('fs-reverse');
const filename = './sample.jsonl';
const readStream = fsR(filename,{})
readStream.on('data',(line) => {
if(line) { // have this check to make sure empty lines are not parsed
console.log(JSON.parse(line))
}
})