Google Sheets クイックスタートが5分でできない


https://developers.google.com/sheets/quickstart/nodejs#step_3_set_up_the_sampl

引用
>Complete the steps described in the rest of this page, and in about five minutes you'll have a simple Node.js command-line application that makes requests to the Google Sheets API.

5分でできるそうです。

できなかったので、上手くいったソースコードを貼っておきます。
下の方に、解決するまでのエラー内容書いてます。興味のある方はどうぞ。
下記をコピペで上手くいくと思います。
step1,2は上手くいっている前提です。

```javascript
var fs = require('fs')
var readline = require('readline')
var { google } = require('googleapis')
var { OAuth2Client } = require('google-auth-library')

// If modifying these scopes, delete your previously saved credentials
// at ~/.credentials/sheets.googleapis.com-nodejs-quickstart.json
var SCOPES = ['https://www.googleapis.com/auth/spreadsheets.readonly']
var TOKEN_DIR =
  (process.env.HOME || process.env.HOMEPATH || process.env.USERPROFILE) +
  '/.credentials/'
var TOKEN_PATH = TOKEN_DIR + 'sheets.googleapis.com-nodejs-quickstart.json'

// Load client secrets from a local file.
fs.readFile('client_secret.json', function processClientSecrets(
  err,
  content
) {
  if (err) {
    console.log('Error loading client secret file: ' + err)
    return
  }
  // Authorize a client with the loaded credentials, then call the
  // Google Sheets API.
  authorize(JSON.parse(content), listMajors)
})

/**
 * Create an OAuth2 client with the given credentials, and then execute the
 * given callback function.
 *
 * @param {Object} credentials The authorization client credentials.
 * @param {function} callback The callback to call with the authorized client.
 */
function authorize(credentials, callback) {
  var clientSecret = credentials.installed.client_secret
  var clientId = credentials.installed.client_id
  var redirectUrl = credentials.installed.redirect_uris[0]
  var oauth2Client = new OAuth2Client(clientId, clientSecret, redirectUrl)

  // Check if we have previously stored a token.
  fs.readFile(TOKEN_PATH, function(err, token) {
    if (err) {
      getNewToken(oauth2Client, callback)
    } else {
      oauth2Client.credentials = JSON.parse(token)
      callback(oauth2Client)
    }
  })
}

/**
 * Get and store new token after prompting for user authorization, and then
 * execute the given callback with the authorized OAuth2 client.
 *
 * @param {google.auth.OAuth2} oauth2Client The OAuth2 client to get token for.
 * @param {getEventsCallback} callback The callback to call with the authorized
 *     client.
 */
function getNewToken(oauth2Client, callback) {
  var authUrl = oauth2Client.generateAuthUrl({
    access_type: 'offline',
    scope: SCOPES
  })
  console.log('Authorize this app by visiting this url: ', authUrl)
  var rl = readline.createInterface({
    input: process.stdin,
    output: process.stdout
  })
  rl.question('Enter the code from that page here: ', function(code) {
    rl.close()
    oauth2Client.getToken(code, function(err, token) {
      if (err) {
        console.log('Error while trying to retrieve access token', err)
        return
      }
      oauth2Client.credentials = token
      storeToken(token)
      callback(oauth2Client)
    })
  })
}

/**
 * Store token to disk be used in later program executions.
 *
 * @param {Object} token The token to store to disk.
 */
function storeToken(token) {
  try {
    fs.mkdirSync(TOKEN_DIR)
  } catch (err) {
    if (err.code != 'EEXIST') {
      throw err
    }
  }
  fs.writeFile(TOKEN_PATH, JSON.stringify(token), err => {
    if (err) return console.error(err)
    console.log('Token stored to', TOKEN_PATH)
  })
}

/**
 * Print the names and majors of students in a sample spreadsheet:
 * https://docs.google.com/spreadsheets/d/1BxiMVs0XRA5nFMdKvBdBZjgmUUqptlbs74OgvE2upms/edit
 */
function listMajors(auth) {
  var sheets = google.sheets('v4')

  sheets.spreadsheets.values.get(
    {
      auth: auth,
      spreadsheetId: '1BxiMVs0XRA5nFMdKvBdBZjgmUUqptlbs74OgvE2upms',
      range: 'Class Data!A2:E'
    },
    function(err, response) {
      if (err) {
        console.log('The API returned an error: ' + err)
        return
      }
      var rows = response.data.values
      if (rows.length == 0) {
        console.log('No data found.')
      } else {
        console.log('Name, Major:')
        for (var i = 0; i < rows.length; i++) {
          var row = rows[i]
          // Print columns A and E, which correspond to indices 0 and 4.
          console.log('%s, %s', row[0], row[4])
        }
      }
    }
  )
}

```

これで上手くいくと思います。失敗したら、教えてください。
ステップ３をやった時に出力されたエラーの解決法をまとめました。

#"TypeError: googlAuth is not a constructor"
github
https://github.com/googleapis/google-auth-library-nodejs/issues/251

>I had the same issue using the Node.js docs and was able to resolve by importing as:
const { GoogleAuth } = require('google-auth-library');

訳
Node.jsドキュメントを使用しても同じ問題があり、次のようにインポートすることで解決できました。 

```
const { GoogleAuth } = require('google-auth-library');

```

次は、別のエラーが出ます。
#TypeError: auth.OAuth2 is not a constructor
github
https://github.com/googleapis/google-auth-library-nodejs/issues/251

>Worked on this a bit more last night and rather than importing via:
const { GoogleAuth } = require('google-auth-library');
I was able to get the example to semi-work by importing OAuth2Client directly via:
const { OAuth2Client } = require('google-auth-library');

訳
次のようにしてOAuth2Clientを直接インポートすることで、この例を半動作させることができました。

```javascript

const { OAuth2Client } = require('google-auth-library');
```

#Cannot read property 'length' of undefined
最後のエラーです。私と同じ状況なら、121行目のあたり、rows.lenthでエラーが出ているはずです。

```javascript

var rows = response.values
if (rows.length == 0) {
```

一回、responseをみてみます。

```
console.log(response)
```

configとかurlとかvaluesとか出てくると思います。valuesを抜粋して記載します。

```javascript

data:
   { range: '\'Class Data\'!A2:E101',
     majorDimension: 'ROWS',
     values:
      [ [Array],
        [Array],
        [Array],
        [Array],
        [Array],
        [Array],
        [Array],
        [Array],
        [Array],
        [Array],
        [Array],
        [Array],
        [Array],
        [Array],
        [Array],
        [Array],
        [Array],
        [Array],
        [Array],
        [Array],
        [Array],
        [Array],
        [Array],
        [Array],
        [Array],
        [Array],
        [Array],
        [Array],
        [Array],
        [Array] ] },
```

どうやら、valuesはdataの中にあるので、プログラムを書き換えます。

```javascript

var rows = response.data.values
if (rows.length == 0) {
```

これで解決するはずです。