“This is the 23rd day of my participation in the First Challenge 2022. For details: First Challenge 2022”

Project source: gitee.com/yang-yiming…

In the last article, we were able to transfer our data to the back end. In this post we’re going to store the data. Instead of storing it in a database, we store it in a JSON file.

Train of thought

Create a DB folder on the server and create a new doing. json under it. Click Create task to read doing. json file, then write data to json file.

Read the file

Node reads files

Let’s refer to the node read file

The document address

const fs = require('fs')
fs.readFile('/Users/joe/test.txt'.'utf8' , (err, data) = > {
  if (err) {
    console.error(err)
    return
  }
  console.log(data)
})
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Let’s apply that to us

The import

// Read the file
const fs = require('fs');
// Find the current path
const path = require('path')
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Let’s take a look at the path

router.post('/create'.function (req, res, next) {
  console.log(__dirname)
  res.send({
    data: 'ok'
  })
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We want to find the DB directoryusepath.join()Methods..Go to the layer above the router.

router.post('/create'.function (req, res, next) {
  console.log(__dirname)
  const dbPath = path.join(__dirname,'.. ')
  console.log(dbPath)
  res.send({
    data: 'ok'})})Copy the code

You can see that the path is now at the Server levelAdd the parameter ‘db’ to the join method, which is the db folder location

const dbPath = path.join(__dirname,'.. '.'db')
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Test reading the file

Write anything in doing. jsonRemember to run the server again.

router.post('/create'.function (req, res, next) {
  console.log(__dirname)
  const dbPath = path.join(__dirname,'.. '.'db')
  console.log(dbPath)
  // '\\'
  fs.readFile(`${dbPath}\/DOING.json`.'utf8'.(err, data) = > {
    if (err) {
      console.error(err)
      return
    }
    console.log(data)
  })
  res.send({
    data: 'ok'})})Copy the code

You can see that the read succeeded.

Combine our logic

Read the parameters passed by the front end

 const newTask = req.body
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Define json file path variables

const dbPath = path.join(__dirname, '.. '.'db')
const dbFile = `${dbPath}\/DOING.json`
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Read the file before you write it

• Is a nested, read file function to call the write operation function.
• Returns if the read or write failsdata:[]
• Finally, if the file is successfully written, new JSON data is returned

📢 The new newData data needs to be treated with JSON.

router.post('/create'.function (req, res, next) {
  // Create new task data
  const newTask = req.body
  const dbPath = path.join(__dirname, '.. '.'db')
  const dbFile = `${dbPath}\/DOING.json`
  // '\'
  /** * read the file before writing the file */
  fs.readFile(dbFile, 'utf8'.(err, data) = > {
    // Return null data on failure
    if (err) {
      console.error(err)
      res.send({
        data: [].code: 0.msg: err
      })
      return
    }
    // Merge the new task data and read the data in the original file
    const newData = JSON.stringify([newTask, ...data])
    fs.writeFile(dbFile, newData, wrerr= > {
      // Return null data on failure
      if (wrerr) {
        console.error(err)
        res.send({
          data: [].code: 0.msg: err
        })
        return
      }
      console.log(newData)
      // The file was successfully written.
      res.send({
        data: newData,
        code: 1.msg: ' '})})})})Copy the code

Problems encountered

When we insert two pieces of data it starts to look like this, broken up into characters.Later it was found that we had some formatting problems. Make the following improvements:

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The service side

Check if the data read is null. Null

 let newData = null;
    // Merge the new task data and read the data in the original file remember to do some JSON processing
    if(data){
       const oldData = JSON.parse(data)
      The stringify() method converts a JavaScript object or value to a JSON string
       newData = JSON.stringify([...oldData,newTask])
       console.log(newData,'nnn')}else{
      // Put it in []
      newData = JSON.stringify([newTask])
    }
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