Phát triển web với PHP và MySQL - p 69 pps

To get some idea of what we are aiming for, take a look at http://www.topica.com Our application will let an administrator create multiple mailing lists and send newsletters to each of t

CHAPTER 28

Building a Mailing List

Manager

After you’ve built up a base of subscribers to your Web site, it’s nice to be able to keep in touch with them by sending out a newsletter In this chapter, we will implement a front end for

a mailing list manager (or MLM) Some MLMs allow each subscriber to send messages to other subscribers Our program will be a newsletter system, in which only the list administrator can send messages We will call our system Pyramid-MLM

This system will be similar to others already in the marketplace To get some idea of what we are aiming for, take a look at

http://www.topica.com Our application will let an administrator create multiple mailing lists and send newsletters to each of those lists separately This application will use file upload to enable an administrator

to upload text and HTML versions of newsletters that they have created offline This means administrators can use whatever software they prefer to create newsletters

Users will be able to subscribe to any of the lists at our site and select whether to receive newsletters in text or HTML

The Problem

We want to build an online newsletter composition and sending system This system should allow various newsletters to be created and sent to users, and allow users to subscribe to one or many of the newsletters

Specifically, the requirements for this system are

• Administrators should be able to set up and modify mailing lists

• Administrators should be able to send text and HTML newsletters to all the subscribers

of a single mailing list

• Users should be able to register to use the site, and enter and modify their details

• Users should be able to subscribe to any of the lists on a site

• Users should be able to unsubscribe from lists they are subscribed to

• Users should be able to store their preference for either HTML formatted or plain text newsletters

• For security reasons, users should not be able to send mail to the lists or to see each other’s email addresses

• Users and administrators should be able to view information about mailing lists

• Users and administrators should be able to view past newsletters that have been sent to

a list (the archive)

Solution Components

There are a number of components we will need to fulfil the requirements The main ones are

setting up a database of lists, subscribers, and archived newsletters; uploading newsletters that

have been created offline; and sending mail with attachments

Setting Up a Database of Lists and Subscribers

We will track the username and password of each system user, as well as a list of the lists they

have subscribed to We will also store each user’s preference for receiving text or HTML

email, so we can send a user the appropriate version of the newsletter

An administrator will be a specialized user with the ability to create new mailing lists and send

newsletters to those lists

A nice piece of functionality to have for a system like this is an archive of previous

newslet-ters Subscribers might not keep previous postings, but might want to look something up An

archive can also act as a marketing tool for the newsletter as potential subscribers can see what

the newsletters are like

Setting up this database in MySQL and an interface to it in PHP will have nothing new or

difficult in it

File Upload

We need an interface to allow the administrator to send newsletters, as mentioned previously

What we haven’t talked about is how administrators will create that newsletter We could

pro-vide them with a form where they could type or paste the newsletter content However, it will

increase the user-friendliness of our system to let administrators create a newsletter in their

favorite editor and then upload the file to the Web server This will also make it easy for an

administrator to add images to an HTML newsletter

For this we can use the file upload capability discussed in Chapter 16, “Interacting with the

File System and the Server.”

We will need to use a slightly more complicated form than we have used in the past We will

require the administrator to upload both text and HTML versions of the newsletter, along with

any inline images that go into the HTML

When the newsletter has been uploaded, we need to create an interface so that the

administra-tor can preview the newsletter before sending it This way, he can confirm that all the files

were uploaded correctly

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Sending Mail with Attachments

For this project, we would like to be able to send users either a plain text newsletter or a

“fancy” HTML version, according to their preference

To send an HTML file with embedded images, we will need to find a way to send attachments PHP’s simple mail()function doesn’t easily support sending attachments Instead, we will use the excellent HTML MIME Mail class created by Richard Heyes This can deal with HTML attachments, and will automatically attach any images that are contained in the HTML file You can get the most up-to-date version of this class from

http://www.heyes-computing.net/scripts/

(It’s also on the CD-ROM in this book.) You are free to use this script in your own work It is released as Postcard-Ware If you use it, send the author a post card The address is on his Web site

Solution Overview

For this project, we will again use an event-driven approach to writing our code, as we did in Chapter 27, “Building a Web-Based Email Service.”

We have again begun by drawing a set of system flow diagrams to show the paths users might take through the system In this case, we have drawn three diagrams to represent the three dif-ferent sets of interactions users can have with the system Users have difdif-ferent allowable actions when they are not logged in, when they are logged in as regular users, and when they are logged in as administrators These actions are shown in Figures 28.1, 28.2, and 28.3, respectively

Show all lists

Not logged in

Login New

Account

F IGURE 28.1

A user can only choose a limited number of actions when he is not logged in.

In Figure 28.1 you can see the actions that can be taken by a user who is not logged in As you

can see, he can log in (if he already has an account), create an account (if he doesn’t already

have one), or view the mailing lists available for signup (as a marketing tactic)

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Not logged in

Change Password

Subscribe

Show other lists

Archive

Show

my lists

Info

Account Settlings

Unsub

F IGURE 28.2

After logging in, users can change their preferences through a variety of options.

Figure 28.2 shows the actions a user can take after logging in He can change his account

set-up (email address and preferences), change his password, and change which lists he is

subscribed to

Admin logged in

Change Password Show

other lists Show

all lists Show

my lists

Subscribe Archive

Info Unsub

Create lists View

Mail

Send Mail

Create Mail

F IGURE 28.3

Administrators have additional actions available to them.

Figure 28.3 shows the actions available if an administrator has logged in As you can see, an

administrator has most of the functionality available to a user, and some additional options

She can also create new mailing lists, create new messages for a mailing list by uploading

files, and preview messages before sending them

Because we have used an event-driven approach again, the backbone of the application is con-tained in one file, index.php, which calls on a set of function libraries An overview of the files

in this application is shown in Table 28.1

the entire application include_fns.php Functions Collection of include files

for this application

data_valid_fns.php Functions Collection of functions for

validating input data

for connecting to the mlm database

mlm_fns.php Functions Collection of functions

spe-cific to this application output_fns.php Functions Collection of functions for

outputting HTML

upload component of the administrator role Sepa-rated out to make security easier

user_auth_fns.php Functions Collection of functions for

authenticating users create_database.sql SQL SQL to set up the mlm

data-base and set up a Web user and an administrative user

We will work our way through the project implementation, beginning with the database in which we will store subscriber and list information

Setting Up the Database

For this application we will need to store details of

• Lists: Mailing lists available for subscription

• Subscribers: Users of the system and their preferences

• Sub_lists: A record of which users have subscribed to which lists (a many-to-many relationship)

• Mail: A record of email messages that have been sent

• Images: Because we want to be able to send email messages that consist of multiple files (that is, text and HTML plus a number of images), we also need to track which images

go with each email

The SQL we have written to create this database is shown in Listing 28.1

L ISTING 28.1 create_database.sql—SQL to Create the mlm Database

create database mlm;

use mlm;

create table lists

(

listid int auto_increment not null primary key, listname char(20) not null,

blurb varchar(255) );

create table subscribers

(

email char(100) not null primary key,

realname char(100) not null,

mimetype char(1) not null,

password char(16) not null,

admin tinyint not null

);

# stores a relationship between a subscriber and a list

create table sub_lists

(

email char(100) not null,

listid int not null

);

create table mail

(

mailid int auto_increment not null primary key,

email char(100) not null,

subject char(100) not null,

listid int not null,

status char(10) not null,

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L ISTING 28.1 Continued sent datetime,

modified timestamp );

#stores the images that go with a particular mail create table images

( mailid int not null, path char(100) not null, mimetype char(100) not null );

grant select, insert, update, delete

on mlm.*

to mlm@localhost identified by ‘password’;

insert into subscribers values (‘admin@localhost’, ‘Administrative User’, ‘H’, password(‘admin’), 1);

Remember that you can execute this SQL by typing mysql -u root -p < create_database.sql You will need to supply your root password (You could, of course, execute this script via any MySQL user with the appropriate privileges; we have just used root here for simplicity.) You should change the password for the mlmuser and the administrator in your script before running it

Some of the fields in this database require a little further explanation, so let’s briefly run through them

The liststable contains a listidand listname It also contains a blurb, which is a description of what the list is about

The subscriberstable contains email addresses (email) and names (realname)of the sub-scribers It also stores their passwordand a flag (admin) to indicate whether or not this user is

an administrator We will also store the type of mail they prefer to receive in mimetype This can be either Hfor HTML or Tfor text

The subliststable contains email addresses (email) from the subscriberstable and listids from the liststable

The mailtable contains information about each email message that is sent through the system

It stores a unique id (mailid), the address the mail is sent from (email), the subject line of the

email (subject), and the listidof the list it has been sent to or will be sent to The actual text

or HTML of the message could be a large file, so we will store the archive of the actual

mes-sages outside the database We will also track some general status information: whether the

message has been sent (status), when it was sent (sent), and a timestamp to show when this

record was last modified (modified)

Finally, we use the imagestable to track any images associated with HTML messages Again,

these images can be large, so we will store them outside the database for efficiency Instead,

we will track the mailidthey are associated with, the pathto the location where the image is

actually stored, and the MIME type of the image (mimetype), for example,image/gif

The SQL shown previously also sets up a user for PHP to connect as, and an administrative

user for the system

Script Architecture

As in the last project, we have used an event-driven approach to this project The backbone of

the application is in the file index.php This script has four main segments, which are

1 Preprocessing: Do any processing that must be done before headers can be sent

2 Set up and send headers: Create and send the start of the HTML page

3 Perform action: Respond to the event that has been passed in As in our last example,

the event is contained in the $actionvariable

4 Send footers

Almost all of the application’s processing is done in this file The application also uses the

function libraries listed in Table 28.1, as mentioned previously

The full listing of the index.php script is shown in Listing 28.2

L ISTING 28.2 index.php—Main Application File for Pyramid-MLM

<?

/**********************************************************************

* Section 1 : pre-processing

*********************************************************************/

include (‘include_fns.php’);

session_start();

$buttons = array();

//append to this string if anything processed before header has output

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L ISTING 28.2 Continued

$status = ‘’;

// need to process log in or out requests before anything else if($email&&$password)

{

$login = login($email, $password);

if($login == ‘admin’) {

$status = “<p><b>”.get_real_name($email).”</b> logged in”

.” successfully as <b>Administrator</b><br><br><br><br><br>”;

$admin_user = $email;

session_register(“admin_user”);

} else if($login == ‘normal’) {

$status = “<p><b>”.get_real_name($email).”</b> logged in”

.” successfully.<br><br>”;

$normal_user = $email;

session_register(“normal_user”);

} else {

$status = “<p>Sorry, we could not log you in with that

email address and password.<br>”;

} } if($action == ‘log-out’) {

session_destroy();

unset($action);

unset($normal_user);

unset($admin_user);

} /**********************************************************************

* Section 2: set up and display headers

*********************************************************************/

// set the buttons that will be on the tool bar if(check_normal_user())

{ // if a normal user