Creating Databases Catch up presentations. Reading & writing files. Sessions. Homework: Starting planning ‘original’ project.
Files Before there were databases, there were simple files. What about using a file for data? Example application: top best scores. Only keep top 5 scores. My demonstration application: http://socialsoftware.purchase.edu/jeanine.meyer/bestscores.html [Simply] requests a player name and a score. Adds to file if big enough. Uses @fclose to mask error. Note: closes file and may or may not re-open. Script displays more than appropriate for production version.
bestscores.html <!DOCTYPE html> <html> <head> <title>Input new scores</title> </head> <body> <form action="bestscores.php"> Player <input type="text" name="player" /> <br/> Score <input type="number" name="score" /> <br/> <input type="submit" value="ENTER"/> </form> </body> </html>
Note The score input is a piece of text. Some browsers may check that that text represents a number, but it is still text. My script will create a scores.txt file if one does not already exist in the subfolder uploads. My script has debugging messages that should be removed for a production system.
strategy Open [connection to] file for reading. Read in the whole file (5 records) into an array variable $data. Close the connection to the file. Each record is name,score Use explode to get the two different things. Convert the score to a number Produce an array $scores of numbers. Compare intval($newscore) to elements in $scores. Find the first one smaller than the proposed new score. Manipulate $data by inserting a record holding “$newname,$newscore\n” Open [connection to] file for writing. For php, writing means erasing whole file and then re-writing it. Write out $data items as records.
bestscores.php <html> <head><title>Best scores </title> </head> <body> <?php $newname = $_GET['player']; $newscore = $_GET['score']; $filen = "uploads/scores.txt"; $open = fopen($filen,"r"); print ("<br/> Just tried to open file to add $newname and $newscore.<br/> "); print ("returned handler is $open <br/>"); if ($open) { $data = file($filen); fclose($open); //file closed for ($i=0;$i<count($data);$i++) { $item = explode(",",$data[$i]); $score = intval($item[1]); $scores[] = $score; print ("current score: $i ".$item[0]." ".$item[1]." <br/>"); }
for($i=0;$i<count($scores);$i++) { if (intval($newscore)>$scores[$i]) { $olddata = $data[$i]; $data[$i] = "$newname,$newscore\n"; for ($j=$i+1;$j<count($scores);$j++) { $nextone = $data[$j]; $data[$j] = $olddata; $olddata = $nextone; } // $j for break; //leave $i for loop } // if newscore better } // $i loop
print ("now will write out new data array print ("now will write out new data array. <hr>"); for($i=0;$i<count($scores);$i++) { print($data[$i]."<br/>"); } // now close the file which was open for reading @fclose($open); print ("<br/>Trying to open $filen for writing <br/>"); $open = fopen($filen,"w");
if ($open) { print("writing out to file <br/>"); for($i=0;$i<count($scores);$i++) { fwrite($open,$data[$i]); } fclose($open); else { print ("<br/> Unable to write updated file. The returned handler value was $open. <br/>"); } // file opened successfully for initial read
else { // need to create file @fclose($open); //may not be necessary since file wasn't opened. print ("scores file doesn't exist yet<br/>"); $open = fopen($filen,"w"); if ($open) { $setsize = 5; //keep 5 top scores fwrite($open,"$newname,$newscore\n"); for ($i=1;$i<$setsize;$i++) { fwrite($open,"X,0\n"); } @fclose($open); } else { print ("couldn't create scores file."); } //needed to create scores file ?> </body> </html>
Application Store results of a "test" with one file / person file name based on "code" Presented as input type=password, but more just identifier If person takes test more than once, add on to the file. This can produce many files! http://socialsoftware.purchase.edu/jeanine.meyer/testquiz.html
testquiz.html function check() { var oksofar = true; if (!((document.f.a1.value.length>0) && (document.f.a2.value.length>0) && (document.f.a3.value.length))){ alert("please submit answer for each question"); oksofar = false; } if (document.f.code.value.length<3){ alert ("The identifying code must be at least 3 characters long"); if (oksofar) { return true;} else { return false; }
body of testquiz <body> Sample quiz <hr/> <form name="f" action="storeanswers.php" onsubmit="return check();" method="POST"> Identifying code: <input type="password" name="code"/> <br/> Answer 1: <input type="text" name="a1"> <br/> Answer 2: <input type="text" name="a2"> <br/> Answer 3: <input type="text" name="a3"> <br/> <input type="submit" value="Submit answers"/> </form> </body>
from storeanswers.php <?php $code = $_POST['code']; $a1 = $_POST['a1']; $a2 = $_POST['a2']; $a3 = $_POST['a3']; $nowp= new DateTime(); $now = $nowp->format('Y-m-d H:i:s'); $answers = "$code $now answers are 1= $a1 2= $a1 3= $a3 ".PHP_EOL; $filen ="uploads/answers" . $code . ".txt" ; $open=fopen($filen,"a"); if ($open) { fwrite($open,$answers); fclose($open); print "Answers stored "; } else { print "Problem with storing answers"; } ?>
sample output: done twice, producing 2 lines jmm 2013-04-06 19:54:54 answers are 1= 23 2= 23 3= 4 jmm 2013-04-06 19:55:09 answers are 1= 20 2= 20 3= 6
More on files Create a subfolder in the folder/directory where you php file is: call it uploads. Consult with CTS to confirm you can do this. May need their help to set permissions
Why use files Very simple structure OR more complex or just different from tables Perhaps with links (pointers) such as family or corporate tree ?
Refrain on 3 tier Some divide the html tier into content versus style, with CSS holding the style. This is the interaction tier. Note: Flash and other languages (Processing, Java, ??) also do more function Middle tier, php, do 'business logic', other function. Information tier, MySQL, holds information! Serves multiple functions. Implemented (possibly) by different groups in an enterprise.
Another tier? or is the 3 tier terminology insufficient Organizations use code and content developed and maintained by others. Web services cloud computing Rented space content such as Google maps ??? Extra credit opportunity to report / comment.
php to php Alternative to cookies or data passed via query strings are Sessions. The sessions may be passed via the HTTP headers Extra credit opportunity: research and do posting on php Sessions Access and set using $_SESSION. This, like $_COOKIE, etc. is an associative array: accessed using names not indices. NOTE: the shopping cart in my store application is stored as a Session variable and is itself an associative array.
<?php session_start(); if (!isset($_SESSION["cart"])) { $_SESSION['cart']=array(); $_SESSION['items'] = 0; $_SESSION['totalprice']=0.00; $cart = array(); } else { //print ("cart already started "); $cart = $_SESSION['cart']; ?>
<html><head><title>Shopping Cart</title> <? require("displaycartfunction.php"); ?> </head> <body> <?php require("opendbo.php"); <h1>Shopping cart</h1> <p> if (isset($_GET['productid'])) { $p_id = $_GET['productid']; $quantity=$_GET['quantity']; $cart[$p_id] = $quantity; $_SESSION['cart'] = $cart; }
displaycart(); ?> <hr> <a href="submitorder.php"> Checkout (submit order)! </a> <a href="orderproduct.php"> More shopping! </a> </body> </html>
displaycart Function stored in file displaycartfunction. Assumes that connection has been made and session started. Makes use of the foreach construction for associative arrays. Since associative arrays don't use index values 0 to length of array, what is the code to examine each element? Answer: foreach($aa as $key=>$qty) { } assuming $aa is the associative array and $key and $qty are variables used in the loop for the keys and values Makes use of number_format($totalprice,2) to produce dollars and cents
<?php //assumes that opendbo called, and session started //when call is made. function displaycart() { global $cart, $DBname, $link, $totalprice; print ("<table border=1>"); print ("<tr><td> Product ID </td> <td> Product Name </td><td> Quantity </td> <td> Total cost </td> </tr>"); $items = 0; //note session variable items not used $totalprice = 0.00; $cart = $_SESSION['cart'];
foreach (@$cart as $pid => $qty) { $items += $qty; //print(" the pid is ".$pid . " and the qty is ". $qty); $query="Select * from catalog where id='$pid'"; //print("query is $query"); $result = mysql_db_query($DBname, $query, $link); $item_price = mysql_result($result,0,"cost"); $item_name = mysql_result($result,0,"p_name"); $item_total_price = $item_price * $qty; $totalprice += $item_total_price; $item_total_pricef = number_format($item_total_price,2); print ("<tr><td> $pid </td> <td> $item_name </td><td> $qty </td> <td> $item_total_pricef </td> </td> "); }
$totalpricef = "$" . number_format($totalprice,2); print("<tr> <td> TOTALS </td> <td> </td> <td> $items items</td><td> $totalpricef </td></tr> </table>"); $_SESSION['items']=$items; $_SESSION['totalprice']=$totalprice; } ?>
Project assignment Design and develop your own database php project work individually and then gather team to determine general idea Make posting to moodle with idea and names of people on team YOU MAY WORK BY YOURSELF or in small group. From more, more is expected. Develop database design (ER diagram) and Data flow diagram Presentations on Monday, 4/24 Complete project, including Storyboard, demo Presentations on Thursday, 5/11
Minimal requirements At least 2 tables and at least 2 SQL statements make use of at least one of localStorage file(s) file uploading sending email At least 2 types of agents. For example: setup and production use. Error handling (form input validation)
Classwork / homework More postings (mainly from those people who haven’t done it) on security, passwords, normalization, and other topics). Think about ‘original / from scratch’ project. Think about your teams. Maybe smaller? It is okay to ‘double-dip’; for example, build on project done for another class or you anticipate doing by adding a database. Make proposal to moodle forum Topic, names of people on team
Planning presentation Tell what your project is Show ER diagram Definition of the tables Show DFD Definition of the tasks and the agents (aka users) and the data stores (database, maybe tables, maybe localStorage) If you have it, perhaps a form This is a presentation of plans!!!!!!