Thiết kế mạng xã hội với PHP - 15 doc

Friends and Relationships
[ 122 ]
Relationships
Our relationships table needs to relate two users together, as well as record the type
of relationship. Since some relationships require mutual consent, we need to indicate
if the non-requesting user accepted the request to connect. The following is a suitable
structure for our relationships table:
Field Type Description
ID Integer, Primary Key, Auto
Increment
A unique ID for the relationship between
the two users
Type ID The type of relationship (a reference to the
relationship_types table)
Usera Integer The user who initiated the relationship, a
relation to the users table
Userb Integer The user who usera initiated a relationship
with, a relation to the users table
Accepted Boolean Indicates if this is a mutual relationship
(which is only used if the relationship type
is a mutual relationship)
Adding friends
Our users can see other users on the site, either by searching for them or viewing
a list of users; from here we can add a link to enable the user to form a relationship.
We have a suitable database structure to facilitate this, but we now need
functionality to connect our users together.
Forming a relationship
Let's walk through what the process should be for our users to form relationships
with each other:
1. View the listing of the user they wish to connect with.
2. Click on a link, or select a relationship type from a list and click on Submit.

3. Check for pre-existing relationships.
4. Check if the relationship type selected is active.
5. Create the relationship in the database.
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6. If the relationship type is mutual, e-mail the other user an approval request
message asking them to conrm the relationship.
7. If the relationship type isn't mutual, e-mail the other user a message
informing them that someone has connected with them.
We already have step one set up—the list of members. For step two, we either need
a link on the user's name or a list of relationship types (which are links or part of a
form submission). Since we have a number of relationship types, let's list the types
of relationships in a drop-down list next to each member as part of a form the user
can submit to create a relationship of that type.
We should create a relationships model for listing relationships, and while we don't
need to do this yet, we could use it to display lists of relationship types too.
A simple method in the model that we can call from the controller to give us a list of
relationship types will sufce. The method below can return a database cache of the
results provided we instruct it to with the
$cache parameter.
public function getTypes( $cache=false )
{
$sql = "SELECT ID as type_id, name as type_name, plural_name as
type_plural_name, mutual as type_mutual FROM relationship_types
WHERE active=1";
if( $cache == true )
{
$cache = $this->registry->getObject('db')->cacheQuery( $sql );
return $cache;

}
else
{
$types = array();
while( $row = $this->registry->getObject('db')->getRows() )
{
$types[] = $row;
}
return $types;
}
}
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Friends and Relationships
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With a list of types at our disposal, we now need to get them and send them to the
template, but only if we are logged in. This should be a new method in our members
controller, which is called after the paginated list is generated (to prevent it being
called when there are no results, and to ensure the code isn't duplicated in the
different listing methods in the controller).
private function formRelationships()
{
if( $this->registry->getObject('authenticate')->isLoggedIn() ==
true )
{
require_once( FRAMEWORK_PATH . 'models/relationships.php');
$relationships = new Relationships( $this->registry );
$types = $relationships->getTypes( true );
If the user is logged in, then a template bit containing a form is placed next to each
member listing, and within there a list of relationship types is dynamically inserted.
$this->registry->getObject('template')->addTemplateBit(

'form_relationship', 'members/form_relationship.tpl.php');
$this->registry->getObject('template')->getPage()->addPPTag(
'relationship_types', array( 'SQL', $types ) );
}
else
{
If the user isn't logged in, then we don't want to show them a form, so we set the tag
to either nothing, or a placeholder comment.
$this->registry->getObject('template')->getPage()->addTag(
'form_relationship', '<! relationship types dropdown >'
);
}
}
We now need to change our member listing template to have a
{form_relationship} tag within the members list loop.
<! START members >
<p><strong>{name}</strong></p>
<p>Keeper of <strong>{dino_name}</strong> a <strong>{dino_gender}
{dino_breed}</strong></p>
{form_relationship}
<hr />
<! END members >
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Finally, we need a template that is inserted into the template variable when the user
is logged in (views/default/templates/members/form_relationship.tpl.php).
This has a template loop within it, into which the relationship types are inserted.
<form action="relationship/create/{ID}" method="post">
<select name="relationship_type">

<! START relationship_types >
<option value="{type_id}">{type_name}</option>
<! END relationship_types >
</select>
<input type="submit" name="create" value="Connect with {name}" />
</form>
Now if we are logged in and take a look at our members list, we see a form next
to each member allowing us to connect with them.
This is a good start, but of course if we or a user clicks on the button, nothing is
going to happen. We now need to create the relationship. To do this we are going
to need a relationship model and a relationship controller.
Relationship model
This needs to encapsulate the data from the relationships table for a specic
relationship, as well as delete, approve, and update existing relationships,
and create new relationships.
<?php
class Relationship{

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Friends and Relationships
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As usual, we start with a number of class variables for the data the model represents
to be stored in, and one for our registry too.
private $registry;
private $usera;
private $userb;
private $approved;
private $id = 0;
private $type;

Our constructor needs to create a new relationship for us, if no ID is passed;
otherwise, it needs to look up an existing relationship in the database. If an ID is
passed, it simply queries the database and populates the class variables accordingly.
/**
* Relationship constructor
* @param Registry $registry the registry
* @param int $id the relationship ID
* @param int $usera the id of user a
* @param int $userb the id of user b
* @param bool $approved if the relationship is approved
* @param int $type the ID of the relationship type
* @return void
*/
public function __construct( Registry $registry, $id=0, $usera,
$userb, $approved=0, $type=0 )
{
$this->registry = $registry;
// if no ID is passed, then we want to create a new relationship
if( $id == 0 )
{
$this->createRelationship( $usera, $userb, $approved, $type );
}
else
{
// if an ID is passed, populate based off that
$sql = "SELECT * FROM relationships WHERE ID=" . $id;
$this->registry->getObject('db')->executeQuery( $sql );
if( $this->registry->getObject('db')->numRows() == 1 )
{
$data = $this->registry->getObject('db')->getRows();

$this->populate( $data['ID'], $data['usera'], $data['userb'],
$data['type'], $data['approved'] );
}
}
}
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When creating a new relationship, there are a number of checks that must be
done rst:
• It must check to ensure there isn't a pre-existing relationship; if there is, we
can't create a new one!
• If one doesn't exist, then it must check the type of relationship:
° If the relationship type is "mutual", then we set the approved
eld to 1, to indicate that the recipient friend must approve
the relationship
° The relationship is then created in the database
/**
* Create a new relationship where one currently doesn't exist,
if one does exist, populate from that
*/
public function createRelationship( $usera, $userb, $approved=0,
$type=0 )
{
// check for pre-existing relationship
$sql = "SELECT * FROM relationships WHERE (usera={$usera} AND
userb={$userb}) OR (usera={$userb} AND userb={$userc})";
$this->registry->getObject('db')->executeQuery( $sql );
if( $this->registry->getObject('db')->numRows() == 1 )
{

// one exists: populate
$data = $this->registry->getObject('db')->getRows();
$this->populate( $data['ID'], $data['usera'], $data['userb'],
$data['type'], $data['approved'] );
}
else
{
// one doesnt exist
if( $type != 0 )
{
// check type for mutual
$sql = "SELECT * FROM relationship_types WHERE ID=" . $type;
$this->registry->getObject('db')->executeQuery( $sql );
if( $this->registry->getObject('db')->numRows() == 1 )
{
$data = $this->registry->getObject('db')->getRows();
// auto approve non-mutual relationships
if( $data['mutual'] == 0 )
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Friends and Relationships
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{
$approved = 1;
}
}
// create the relationsip
$insert = array();
$insert['usera'] = $usera;
$insert['userb'] = $userb;
$insert['type'] = $type;

$insert['approved'] = $approved;
$this->registry->getObject('db')->insertRecords(
'relationships', $insert );
$this->id = $this->registry->getObject('db')->lastInsertID();
}
}
}
The model also requires a setter method to update the approved status
of the relationship.
/**
* Approve relationship
* @return void
*/
public function approveRelationship()
{
$this->approved = true;
}
A delete method is also useful to delete the relationship.
/**
* Delete relationship
* @return void
*/
public function delete()
{
$this->registry->getObject('db')->deleteRecords( 'relationships',
'ID=' . $this->id, 1 );
$this->id = 0;
}
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We have our standard save method that either creates a new record or updates an
existing one depending on whether the relationship is being created or saved.
/**
* Save relationship
* @return void
*/
public function save()
{
$changes = array();
$changes['usera'] = $this->usera;
$changes['userb'] = $this->userb;
$changes['type'] = $this->type;
$changes['accepted'] = $this->accepted;
$this->registry->getObject('db')->updateRecords( 'relationships',
$changes, "ID=" . $this->id );
}

/**
* Populate relationship object
* @param int $id the user id
* @param int $usera user a
* @param int $userb user b
* @param int $type the type
* @param bool $approved
* @return void
*/
private function populate( $id, $usera, $userb, $type, $approved )
{
$this->id = $id;

$this->type = $type;
$this->usera = $usera;
$this->userb = $userb;
$this->approved = $approved;
}
}
?>
Relationship controller
With a relationship model in place to make creating, updating, and deleting
relationships easy, we need a controller to process the user's request to create,
approve, or reject a relationship.
private function createRelationship( $userb )
{
if( $this->registry->getObject('authenticate')->isLoggedIn() )
{
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Friends and Relationships
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If we are logged in, then we take our user ID, the ID of the user we wish to connect
with, and the relationship type, and create our relationship.
$usera = $this->registry->getObject('authenticate')->
getUser()->getUserID();
$type = intval( $_POST['relationship_type'] );
require_once( FRAMEWORK_PATH . 'models/relationship.php');
$relationship = new Relationship( $this->registry, 0, $usera,
$userb, $type, 0 );
if( $relationship->isApproved() )
{
If the relationship is automatically approved, we can e-mail the user to tell them they
have a new connection, and then display a message to the logged in user.

// email the user, tell them they have a new connection
/**
* Can you remember how the email sending object works?
*/
$this->registry->errorPage('Relationship created', 'Thank
you for connecting!');
}
else
{
If the relationship isn't automatically approved, we can e-mail the user to tell them
they have a new pending connection, and display a message to the logged in user.
// email the user, tell them they have a new pending
connection
/**
* Can you remember how the email sending object works?
*/
$this->registry->errorPage('Request sent', 'Thanks for
requesting to connect!');
}
}
else
{
If the user isn't logged in, we display an error message.
$this->registry->errorPage('Please login', 'Only logged in
members can connect on this site');
// display an error
}
}
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Now if we click on the Connect with button on the relationship form, our
relationship is created and we are shown a conrmation message. This could
be expanded in the future to use AJAX to display the notication on the previous
page, without causing the page to reload.
Mutual relationships—accepting or rejecting
a request
If a relationship type is mutual, we need users to be able to see, accept, and reject
these requests.
• View list of requests
• Accept: Update the database record
• Reject: Remove the database record
Pending requests
Pending requests can be found by querying the database for relationships where the
userb column is the current logged in user, and the relationship isn't approved. This
query should be in our relationships model.
New model method
Our model method should take parameters for usera, userb, and approved, and
if either of the user parameters are set, lter based on those users, returning
a cached query.
public function getRelationships( $usera, $userb, $approved=0 )
{
$sql = "SELECT t.name as type_name, t.plural_name as
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