I created a web form using Google Apps Script, where form visitors would see result.html after data submission. However, the data may be submitted multiple times if visitors reload the result.html by pressing F5, Ctrl R, ignoring the alert of resubmission. The same concern has already been posted here, and I tried implementing one of the solutions for that, but in vain.

I have now four files in the same project of Google Apps Script:

index.html that produces the form
JavaScript.html that defines functions used in index.html
result.html that is presented after the form submission
code.gs that shows the form by doGet(), and processes the submitted data and presents result.html by doPost(). include() defined in this file enables to input JavaScript.html into index.html

The solution I have tried is adding the following JavaScript code result.html. I also add that to JavaScript.html so that the code is to be executed in index.html, too.

<script>
    if ( window.history.replaceState ) {
        window.history.replaceState( null, null, window.location.href );
    }
</script>

However, the resubmission still occurs when I reload the result.html even after I added that code to both result.html and index.html. What am I missing?

`index.html`

<!DOCTYPE html>
<html>
  <head>
    <base target="_top">
    <!-- <?!= include("css"); ?> -->
  </head>

  <body onl oad="addOptions()">   <!--Execute addOptions function immediately after a page has been loaded-->
    <form  action="<?!= getScriptUrl(); ?>" method="post" onSubmit="document.getElementById('submit').disabled=true;">
      <div>
        <h1 id="Question">
          Choose either cheesecake or chocolate cake.
        </h1>
          <select id="dropdownList" name="cake" > 
          </select>
      </div>

      <div >
        <input type="submit" name="" value="Submit">
      </div>
    </form>
  </body>
  <?!= include('JavaScript') ?>
</html>

`JavaScript.html`

<script>
  function addOptions() {
    /*This will call server-side Apps Script function getAvailableExps and if it is successful, 
    it will pass the return value to function addListValues which will add options to the drop down menu*/
    google.script.run
      .withFailureHandler(onFailure)
      .withSuccessHandler(addListValues)
      .getAvailableExps();
  }

  function addListValues(values) { 
    //Add options to drop down menu using the values of parameter 'values'.     
    for (var i = 0; i < values.length; i  ) {
      var option = document.createElement("option");
      option.text = values[i][0];
      option.value = values[i][0];
      var select = document.getElementById("dropdownList");
      select.appendChild(option);
    }
  }

  function onFailure(err) {
    alert('Error: '   err.message);
  }

  if ( window.history.replaceState ) {
        window.history.replaceState( null, null, window.location.href );
  }
</script>

`result.html`

<!DOCTYPE html>
<html lang="ja">
  <head>
    <meta charset="UTF-8">
    <base />
    <title>Thank you for your order!</title>
    <!-- <?!= include('css'); ?> -->
  </head>
  <script>
    if ( window.history.replaceState ) {
      window.history.replaceState( null, null, window.location.href );
    }
  </script>
  <body>
    <p>
      Don't forget what you've ordered!
    </p>
  </body>
</html>

`code.gs`

var sheetID = "............................................";
var inventory_sheet = "Inventory";

function doGet(){
  return HtmlService.createTemplateFromFile("index").evaluate();
}

function include(filename){
  return HtmlService.createHtmlOutputFromFile(filename).getContent();
}

function getScriptUrl() {
  var url = ScriptApp.getService().getUrl();
  Logger.log(url);
  return url;
}

function doPost(e){
  var ss = SpreadsheetApp.openById(sheetID);
  var sh = ss.getSheets()[0];
  sh.appendRow([String(e.parameters.cake)]);

  //update Inventory
  var inventory = ss.getSheetByName(inventory_sheet);
  var row = inventory.createTextFinder(e.parameters.cake).findNext().getRow();
  var range = inventory.getRange(row, 2);
  var data = range.getValue();
  range.setValue(parseInt(data - 1))

  return HtmlService.createTemplateFromFile("result").evaluate(); 
  
}

function getAvailableExps(){
  var inventory = SpreadsheetApp.openById(sheetID).getSheetByName(inventory_sheet);
  var data =  inventory.getRange(2, 1, 2, 2).getValues();
  var filtered = data.filter(arr =>  arr[1] > 0 || arr[1] != ''); //remove exp to array if quantity is 0 or empty
  return filtered;
}

CodePudding user response：

In your situation, how about checking the submit using PropertiesService? When your script is modified, it becomes as follows.

Modified script:

In this modification, 2 functions of doGet and doPost of code.gs are modified.

`doGet`

function doGet() {
  PropertiesService.getScriptProperties().setProperty("key", "sample");
  return HtmlService.createTemplateFromFile("index").evaluate();
}

`doPost`

function doPost(e) {
  var p = PropertiesService.getScriptProperties();
  if (p.getProperty("key") == "sample") {

    var ss = SpreadsheetApp.openById(sheetID);
    var sh = ss.getSheets()[0];
    sh.appendRow([String(e.parameters.cake)]);

    //update Inventory
    var inventory = ss.getSheetByName(inventory_sheet);
    var row = inventory.createTextFinder(e.parameters.cake).findNext().getRow();
    var range = inventory.getRange(row, 2);
    var data = range.getValue();
    range.setValue(parseInt(data - 1))

    p.deleteProperty("key");
  }

  return HtmlService.createTemplateFromFile("result").evaluate();
}

When you access to your Web Apps, sample is stored by setProperty("key", "sample") in doGet(). And, when the HTML form is submitted, the PropertiesService is checked in doPost(e). When sample is existing, the data is put, and the PropertiesService is cleared. By this, even when the submitted page is reopened, the PropertiesService is not existing. By this, the resubmitted can be avoided.

Reference:

Properties Service