nodejs逐行处理文本文件

最新推荐文章于 2024-08-30 16:17:16 发布

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本文介绍了一种使用Node.js将SQL插入语句转换为JSON格式的方法，特别关注地理数据的处理。通过使用minimist解析命令行参数，readline逐行读取文件，并将特定字段转换为数字，实现了从SQL到JSON的高效转换。

INSERT INTO `bs_province` VALUES ('1', '110000', '北京', '北京', '116.405289', '39.904987', '1', '2019-02-28 17:16:58', '2019-02-28 17:17:05', '', '0', '00000000');
INSERT INTO `bs_province` VALUES ('2', '120000', '天津', '天津', '117.190186', '39.125595', '2', '2019-02-28 17:16:58', '2019-02-28 17:17:05', '', '0', '00000000');

我希望把上面的数据变成如下的json

[
	{"code":"110000","name":"北京","lng":116.405289,"lat":39.904987,"sort":1},
	{"code":"120000","name":"天津","lng":117.190186,"lat":39.125595,"sort":2}
]

代码使用minimist处理参数，使用流来读写文件，使用readline来逐行读文件，并把lng, lat, sort列转化为数字。

// usage:
// node sql2json.js -i bs_province.sql -o province.json --columns="code, name, lng, lat, sort" --numbers="1, 2, 4, 5, 6"
// node sql2json.js -i bs_city.sql -o city.json --columns="code, name, pcode, lng, lat, sort" --numbers="1, 2, 4, 5, 6, 7"
// node sql2json.js -i bs_area.sql -o district.json --columns="code, name, pcode, lng, lat, sort" --numbers="1, 3, 2, 5, 6, 7"
// node sql2json.js -i bs_street.sql -o street.json --columns="code, name, pcode, lng, lat, sort" --numbers="1, 3, 2, 5, 6, 7"
const readline = require("readline");
const fs = require("fs");
const minimist = require("minimist");

const args = minimist(process.argv.slice(2));
if (args.i) {
  args.input = args.i;
}
if (args.o) {
  args.output = args.o;
}
const columns = args.columns.split(",");
const numbers = args.numbers.split(",");
const count = numbers.length;
if (columns.length !== numbers.length) {
  console.error("columns.length != numbers.length");
  return 1;
}
for (let i = 0; i < count; ++i) {
  columns[i] = columns[i].trim();
  numbers[i] = numbers[i].trim();
}

let firstLine = true;
const input = fs.createReadStream(args.input);
const output = fs.createWriteStream(args.output);
output.write("[\n");
const rl = readline.createInterface({ input });
rl.on("line", line => {
  if (line.startsWith("INSERT INTO")) {
    if (!firstLine) {
      output.write(",\n");
    }
    line = line.replace(/^INSERT INTO `.*` VALUES \(/, "");
    line = line.replace(/\);$/, "");
    const parts = line.split(", ");
    const o = {};
    for (let i = 0; i < count; ++i) {
      const part = parts[numbers[i]];
      const column = columns[i];
      o[column] = part.substring(1, part.length - 1);
      if (column === "lng" || column === "lat" || column === "sort") {
        o[column] = Number(o[column]);
      }
    }
    const str = "\t" + JSON.stringify(o);
    output.write(str);
    firstLine = false;
  }
});
input.on("end", () => {
  output.write("\n]\n");
});

return 0;