Post Array From HTML Form To PHP (Simple Examples)

Welcome to a tutorial on how to post an array from an HTML form to PHP. The “standard” HTML form fields are easy enough. Just add the name attribute to the fields, submit the form, and that’s it. But what if we want to post an array instead?

But how about doing this with AJAX? How about multi-dimensional arrays? How do we handle the post data in PHP? That is what we will walk through in this guide, with examples. Read on to find out!

 

 

TABLE OF CONTENTS

 

 

EXAMPLE CODE DOWNLOAD

Source code on GitHub Gist

Just click on “download zip” or do a git clone. I have released it under the MIT license, so feel free to build on top of it or use it in your own project.

 

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VIDEO TUTORIAL

 

EXAMPLE 1) POST A SIMPLE ARRAY TO PHP

1A) THE HTML

<!-- JUST APPEND [] TO THE NAME -->
<form method="post" action="1b-basic.php">
  <label>Favorite Colors</label>
  <input type="text" name="colors[]" required value="red">
  <input type="text" name="colors[]" required value="green">
  <input type="text" name="colors[]" required value="blue">
  <input type="submit" value="Submit">
</form>

As in the introduction, we only need to append square brackets [] behind the name to POST arrays to the PHP script.

 

1B) SERVER-SIDE PHP

<?php
// (A) $_POST WILL CONTAIN ALL THE POSTED FORM DATA AS USUAL
print_r($_POST);

// (B) BUT $_POST["COLORS"] WILL BE AN ARRAY
foreach ($_POST["colors"] as $color) {
  echo "$color<br>";
}

Yep, this should be straightforward enough. Since we defined colors[], $_POST["colors"] will be an array.

 

 

EXAMPLE 2) POST NESTED ARRAY TO PHP

2A) THE HTML

<!-- USE NAME[KEY][] TO SPECIFY MULTI-DIMENSION ARRAYS -->
<form method="post" action="2b-nested.php">
  <label>Favorite Colors</label>
  <input type="text" name="fav[color][]" required value="red">
  <input type="text" name="fav[color][]" required value="green">
  <input type="text" name="fav[color][]" required value="blue">
 
  <label>Favorite Food</label>
  <input type="text" name="fav[food][]" required value="bacon">
  <input type="text" name="fav[food][]" required value="eggs">
 
  <input type="submit" value="Submit">
</form>

Multi-dimensional array fields are not that difficult either – Just use 2 square brackets, and give the first one a key. That’s it, done.

 

2B) SERVER-SIDE PHP

<?php
// (A) $_POST["fav"] IS A MULTI-DIMENSIONAL ARRAY
print_r($_POST["fav"]);
 
// (B) FAVORITE COLORS
print_r($_POST["fav"]["color"]);
 
// (C) FAVORITE FOOD
print_r($_POST["fav"]["food"]);

No mystery here either – $_POST["fav"] is a multi-dimensional array as expected.

 

 

EXAMPLE 3) POSTING ARRAY WITH AJAX

3A) THE HTML

<form id="myForm" method="post" onsubmit="return save()">
  <label>Favorite Colors</label>
  <input type="text" name="fav[color][]" required value="red">
  <input type="text" name="fav[color][]" required value="green">
  <input type="text" name="fav[color][]" required value="blue">
 
  <label>Favorite Food</label>
  <input type="text" name="fav[food][]" required value="bacon>
  <input type="text" name="fav[food][]" required value="eggs">
 
  <input type="submit" value="Submit">
</form>

Not much of a difference here – Still the same HTML form, but using onsubmit="return save()" to use Javascript AJAX to handle the submission instead.

 

3B) THE JAVASCRIPT

function save () {
  // (A) GET FORM DATA
  var form = document.getElementById("myForm"),
      data = new FormData(form);

  // (B) TO MANUALLY APPEND MORE DATA
  data.append("address[]", "Foo Street 123");
  data.append("address[]", "Hello World #234");

  // (C) AJAX FETCH
  fetch("3c-AJAX.php", { method:"POST", body:data })
  .then(res => res.text())
    .then(res => {
    console.log(res);
    // DO SOMETHING
  });
  return false;
}

Yep, simple as “ABC”.

1. Collect data from the HTML form.
2. Optional, we can manually append more fields to the data.
3. Lastly, send the data to the server, and read the server response as text.

 

3C) SERVER PHP

<?php
print_r($_POST);

Nothing to see here… Just a dummy script that will echo whatever is being submitted.

 

 

 

ONLY FOR PHP!

Before the toxic trolls get angry – Take note that the above method of name="something[]" works for PHP, but it can be different for other languages. For example, some languages may require all the name attribute to be the same instead:

<input type="text" name="color" value="Red">
<input type="text" name="color" value="Green">
<input type="text" name="color" value="Blue">

 

 

JSON ENCODE-DECODE

To better support cross-platform data exchange, the common industry practice is to turn the array into a flat string, using JSON encode:

<script>
// (A) ARRAY TO STRING
var colors = ["Red", "Green", "Blue"];
colors = JSON.stringify(colors);
console.log(colors); // ["Red","Green","Blue"]
 
// (B) APPEND DATA
var data = new FormData();
data.append("colors", colors);
 
// (C) SEND!
fetch("4b-JSON.php", { method:"POST", body:data })
.then(res => res.text())
.then(txt => console.log(txt));
</script>

On the server side, we can do a JSON decode to get the array back.

<?php
$colors = json_decode($_POST["colors"]);
print_r($colors);

P.S. Any programming language can encode-decode a JSON string so long as there is a library or parser.

 

LINKS & REFERENCES

• PHP POST
• PHP GET
• Sending form data – MDN
• Form Data – MDN
• Working with JSON – MDN