Execute index of a folder if exists, if not execute php file - .htaccess

Question

I want this example URL:
example.com/folder/phpfile
To redirect to:
example.com/folder/phpfile.php
It works perfectly, but I also want to be able to execute the index.php file of any folder just by this URL
http://example.com/folder
or
http://example.com/folder/
or maybe
example.com/folder/subfolder
But I don't know how, I'm using RewriteCond %{REQUEST_FILENAME}, as I understand this is a condition to know if the requested file name is either a file or a folder. But I can't make it work.
This is my current .htaccess:
Options -Indexes
RewriteEngine On
RewriteCond %{REQUEST_FILENAME} !-d
RewriteCond %{REQUEST_FILENAME} !-f
RewriteRule ^([a-zA-Z0-9-_])$ $1.php [NC,L]

Answer 1

You can meet your requirement using this code in root .htaccess:
# by default load index.php from a path
DirectoryIndex index.php
# make sure trailing slash is present for directories
DirectorySlash On
RewriteEngine On
# load /dir/file.php if request is for /dir/file
RewriteCond %{REQUEST_FILENAME} !-d
RewriteCond %{DOCUMENT_ROOT}/$1\.php -f [NC]
RewriteRule ^(.+?)/?$ /$1.php [L]

Answer 2

here is one more thing that we can do to further clean our URLs, i.e., hiding the entry script index.php in the URL. This requires us to configure the Web server as well as the urlManager application component.
We first need to configure the Web server so that a URL without the entry script can still be handled by the entry script. For Apache HTTP server, this can be done by turning on the URL rewriting engine and specifying some rewriting rules. We can create the file /wwwroot/blog/.htaccess with the following content. Note that the same content can also be put in the Apache configuration file within the Directory element for /wwwroot/blog.
RewriteEngine on
# if a directory or a file exists, use it directly
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
# otherwise forward it to index.php
RewriteRule . index.php
We then configure the showScriptName property of the urlManager component to be false.
Now if we call $this->createUrl('post/read',array('id'=>100)), we would obtain the URL /post/100. More importantly, this URL can be properly recognized by our Web application.