# First Forms - POST and GET
## Key Ideas
* POST and GET
* isset()
* empty()
* print_r() and var_dump()
* Use isset() and empty() to write a submit and POST on one PHP page
```{admonition} Definition - GET
__GET__ is used to request data from a specified resource. Note that the query string (name/value pairs) is sent in the URL of a GET request:
demo_form.php?name1=value1&name2=value2
https://www.w3schools.com/tags/ref_httpmethods.asp
```
**Some notes on GET requests:**
- GET requests can be cached
- GET requests remain in the browser history
- GET requests can be bookmarked
- GET requests should never be used when dealing with sensitive data
- GET requests have length restrictions
- GET requests are only used to request data (not modify)
https://www.w3schools.com/tags/ref_httpmethods.asp
```{admonition} Definition - POST
__POST__ is used to send data to a server to create/update a resource.
The data sent to the server with POST is stored in the request body of the HTTP request:
https://www.w3schools.com/tags/ref_httpmethods.asp
```
**Some notes on POST requests:**
- POST requests are never cached
- POST requests do not remain in the browser history
- POST requests cannot be bookmarked
- POST requests have no restrictions on data length
https://www.w3schools.com/tags/ref_httpmethods.asp
## Code Examples
```{mermaid}
flowchart TD
A[Home page\nindex.html] --> B[Form1\nform1.html]
A --> C[Form2\nform2.html]
A --> D[Form & Results\nForm3.php]
A --> E[Form & Results\nForm4.php]
B --> B1[Form Results\nform1a.php]
C --> C1[Form Results\nform2a.php]
```
### Home Page - index.html
```html
Home Page
POST and GET Examples
Form 1
Form 2
Form 3
Form 4
```
### First Form - form1.html
```html
Form1a
Results from form1
");
var_dump($_POST);
echo("
");
print_r($_POST);
echo("
");
echo("
Hello ".$_POST['stuName']."
");
echo("Your major is ".$_POST['stuMajor']."
");
?>
Home
```
### Form2 (GET) - form1.html
```html
Home Page
Form 2
```
### Results - form2a.php
```php
Form2a
Results from form2a
");
var_dump($_GET);
echo("
");
print_r($_GET);
echo("
");
echo("
Hello ".$_GET['stuName']."
");
echo("Your major is ".$_GET['stuMajor']."
");
?>
Home
```
### Form and Results - _isset()_ and _empty_ - form3.php
```php
Form 3
Form 3
");
var_dump($_POST);
echo("
");
print_r($_POST);
echo("
");
echo("isset
");
if(isset($_POST['stuName']))
{
echo("
Hello ".$_POST['stuName']."
");
echo("Your major is ".$_POST['stuMajor']."
");
}
echo("
");
echo("Not Empty
");
if(!empty($_POST['stuName']))
{
echo("
Hello ".$_POST['stuName']."
");
echo("Your major is ".$_POST['stuMajor']."
");
}
?>
Home
```
### Form4 - form4.php
This is the standard format for doing PHP pages with one page.
```php
Form 4
');
}
else
{
echo("
Hello ".$_POST['stuName']."
");
echo("Your major is ".$_POST['stuMajor']."
");
}
?>
Home
```