“This is the 17th day of my participation in the First Challenge 2022.

background

  • NPM package used by BFF Clientrequest-promise-nativeRequest microservice interface return ID precision missing

1713166949059674112 = > 1713166949059674000

Why is it missing?

  • Math.pow(2, 53) is the largest integer that can be accurately represented in JS. Math.pow(2, 53) If 9007199254740992 is greater than 9007199254740992, the precision may be lost
    • Reference: zhuanlan.zhihu.com/p/100353781
  • request-promise-nativeInitiate a request whenoptions.jsonDon’t forfalseWill useJSON.parseParsing the body
if (self._json) {
  try {
    response.body = JSON.parse(response.body, self._jsonReviver)
  } catch (e) {
    debug('invalid JSON received', self.uri.href)
  }
}
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Minimum demo

Build service API

Build Java Web Api

  • Reference: Building a RESTful Web Service
  • Modify the Service layer to make the id minimum greater than the JS precision limit
    public long getId(a) {
        return id + 1713166949059674112L; } * Modify the Controller layer to add post requests@PostMapping("/greeting_create")
    public Greeting createGreeting(@RequestParam(value = "name", defaultValue = "World") String name) {
        return new Greeting(counter.incrementAndGet(), String.format(template, name));
    }
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Second, the request

  • GET request:curl http://localhost:8080/greeting
  • POST request:curl -X POST http://localhost:8080/greeting_create
{"id":1713166949059674120."content":"Hello, World!"}
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The solution

1. Obtain the string of the response bodyJSONbig 将 idConvert to a string

  • Advantages: Only the current request is affected
  • Disadvantages: Does not support POST request mode,
    • Sending parameters through JSON is not supported
    • Passing parameters through form + JSON: false requires backend interface support
  • A GET request
const rp = require('request-promise-native');
const jsonBigInt = require('json-bigint');

  const getOptions = {
    'method': 'GET'.json: false.'url': 'http://localhost:8080/greeting'};const getRes = await rp(getOptions);
  console.log('get result: ', jsonBigInt.parse(getRes));
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  • POST request: not supported, json is occupied, must be executedJSON.parse
const rp = require('request-promise-native');
const jsonBigInt = require('json-bigint');

  const postOptions = {
    'method': 'POST'.'url': 'http://localhost:8080/greeting_create'.json: { name: 'test'}};const postRes = await rp(postOptions);
  console.log('post result: ', jsonBigInt.parse(postRes));
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2. UseJSONbig.parse()replaceJSON.parse()

  • Advantages: Simple implementation, support POST
  • Disadvantages: Affects all json.parse () parsing
const rp = require('request-promise-native');
const jsonBigInt = require('json-bigint');

async function jsonBigReplaceParse() {
  const oldParse = JSON.parse;
  JSON.parse = jsonBigInt.parse;
  const postOptions = {
    'method': 'POST'.'url': 'http://localhost:8080/greeting_create'.json: { name: 'test'}};const postRes = await rp(postOptions);
  console.log('post result: ', postRes);
  JSON.parse = oldParse;
}
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~

Thanks for reading!

~

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Hello everyone, I am the author of “programming Samadhi”, I am king Yi, my public account is “programming Samadhi”, welcome to pay attention, I hope you can give me more advice!