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- Dr. Steven Bitner
Uploading files (chapter 19)
http://kc-sce-
sphp01.kc.umkc.edu/~bitners/dashboard.php
Uploading files Dr. Steven Bitner Uploading files (chapter 19) - - PowerPoint PPT Presentation
Uploading files Dr. Steven Bitner Uploading files (chapter 19) - - PowerPoint PPT Presentation
Uploading files Dr. Steven Bitner Uploading files (chapter 19) http://kc-sce- sphp01.kc.umkc.edu/~bitners/dashboard.php How does that work Several different approaches We'll only cover one to avoid confusion Steps follow Server
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How does that work
Several different approaches
We'll only cover one to avoid confusion
Steps follow
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Server settings
First things first Use phpinfo() again http://kc-sce-sphp01.kc.umkc.edu/~bitners/junk.php Look for:
file_uploads max_file_uploads upload_max_filesize
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Another superglobal
$_GET,$_POST,$_REQUEST, and $_SERVER have a friend Called $_FILES
Just like the others, it is created at the right time
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Interface with users
http://kc-sce-
sphp01.kc.umkc.edu/~bitners/code.php?page=dashboard.p hp
Two elements of note
<input type = "hidden" name = "MAX_FILE_SIZE" value = "2000000" /> <input type = "file" name = "bestFileEver" />
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Submit
Of course don't forget your <form> and <button> tags Make sure that your form method is POST and that you set
the action attribute to the file you intend to use for uploading <form action = "uploadMe.php" method = "POST" enctype= "multipart/form-data">
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enctype?
The enctype (encoding type) attribute for the form tag tells
the browser that you will be including different encoding formats
This is similar to the multipart information needed for
mailing an attachment or including HTML in an email
Without this attribute properly set, your script will fail
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$_FILES is alive
When the user clicks submit, the $_FILES superglobal arrray
is created in much the same manner as $_POST is created
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Where to store files
Server directory – The book way (more sample code)
pros:
easiest approach, since the file system does this automatically less open to injection attacks
cons:
Much harder to control access File itself is stored separately from metadata
Database – this is the way we'll discuss
pros:
Have total control over who can view
cons:
More complex to program Injection attacks can happen if you don't use prepared statements
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Database storage of files
Need a database table for storing files with:
name – this will store the name of the file
CHAR or VARCHAR
size – to store the size of the file
INT $_FILES['size'] is a quick bit of error checking to make sure that a file was uploaded
type – in order to send the appropriate header, or include the correct data
type in the form src attribute
CHAR or VARCHAR
content – the file itself
any member of the BLOB family
TINYBLOB – up to 28 bytes = 256B BLOB – up to 216 bytes = 64KB MEDIUMBLOB – up to 224 bytes = 16MB LONGBLOB – up to 232 bytes = 4GB
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Uploading
Like all of PHP
, you can choose a functional or an object
- riented approach
You can hard code this functionality inline, but then the code is
not re-usable
http://kc-sce-
sphp01.kc.umkc.edu/~bitners/code.php?page=resources/u ploader.php
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Did it work?
Check your database table directly
kc-sce-sphp01.kc.umkc.edu:8888
If it's in there, you're almost done
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Viewing
We don't store files for the sake of wasting disk space Once again two approaches
Display by encoding the data from the db and using the
following image tag
<img src="data:image/jpeg;base64,ENC_FILE" />
ENC_FILE above is the value returned from
base64_encode ($file);
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More common approach
Use a script as an image src Send header from the script
<img src="showImage.php?id=8" />
Tons of examples online
Essentially, send the appropriate
headers and then echo the content from the database