I’ve been working on the Student enrollment example/tutorial for ATK and am stuck on the use of ref()’s via linking tables.
A basic ER of the system is below:
[Student] ||---|< [class_has_student] >|---|| [class] >|----|| [subject]
Where a Subject stores the subjects name, subject code, which semester(s) it can run in and a description.
A class is the lecture/tutorial that is offered to student’s for a given Subject over a given period. A student can enrol in a Class and the relation is stored in the class_has_student table.
For the basic example I wish to show a particular students details and show the classes (with subject name) they are enrolled in. I’m using a view template to display the student details (name, etc)
and any classes (with subject name) they are enrolled in using the Lister class. The main problem is when trying to list the subjects a particular student is enrolled in using:
$student_detail= $student->ref('ClassHasStudent2')->ref('class_idclass')
Rather than retrieving all subjects the student is enrolled in, its retrieving all subjects from the DB.
Please see below for the Page, Models and template code for this example, and the modified Table.php class to get it to work (sorry for the length).
Thanks for your help.
Models
“class” table
+-------------------+---------+------+-----+---------+----------------+
| Field | Type | Null | Key | Default | Extra |
+-------------------+---------+------+-----+---------+----------------+
| idclass | int(11) | NO | PRI | NULL | auto_increment |
| subject_idsubject | int(11) | NO | MUL | NULL | |
| date_start | date | YES | | NULL | |
| date_end | date | YES | | NULL | |
| max_students | int(11) | YES | | NULL | |
+-------------------+---------+------+-----+---------+----------------+
select * from class;
+---------+-------------------+------------+------------+--------------+
| idclass | subject_idsubject | date_start | date_end | max_students |
+---------+-------------------+------------+------------+--------------+
| 1 | 2 | 2012-09-10 | 2012-09-30 | 10 |
| 2 | 1 | 2012-09-08 | 2012-09-30 | 30 |
| 3 | 3 | 2012-10-01 | 2012-10-31 | 35 |
| 4 | 2 | 2012-09-19 | 2012-09-29 | 10 |
+---------+-------------------+------------+------------+--------------+
class.php
<?php
class Model_Class extends Model_Table {
public $table='class';
public $entity_code='class';
public $id_field='idclass';
function init(){
parent::init();
$this->hasOne('Subject','subject_idsubject','name', 'subject_name');
$this->addField('date_start')->type('date')->caption('Start');
$this->addField('date_end')->type('date')->caption('End');
$this->addField('max_students')->type('int');
$this->hasMany('ClassHasStudent','class_idclass', 'idclass');
}
}
“student” table
+------------+-------------+------+-----+---------+----------------+
| Field | Type | Null | Key | Default | Extra |
+------------+-------------+------+-----+---------+----------------+
| idstudent | int(11) | NO | PRI | NULL | auto_increment |
| student_id | varchar(45) | NO | | NULL | |
| name | varchar(45) | NO | | NULL | |
+------------+-------------+------+-----+---------+----------------+
select * from student;
+-----------+------------+--------+
| idstudent | student_id | name |
+-----------+------------+--------+
| 1 | T123 | Tom |
| 2 | L222 | Lizley |
| 3 | B123 | Betty |
| 4 | H33 | Homer |
| 5 | N42 | Nick |
+-----------+------------+--------+
student.php
<?php
class Model_Student extends Model_Table {
public $table='student';
public $entity_code='student';
public $id_field='idstudent';
public $title_field='name';
function init(){
parent::init();
$this->addField('student_id')->caption('Student ID');
$this->addField('name')->caption('Name');
$this->hasMany('ClassHasStudent', 'student_idstudent', 'idstudent');
}
}
Mysql “class_has_student” table
+---------------------+-------------+------+-----+---------+----------------+
| Field | Type | Null | Key | Default | Extra |
+---------------------+-------------+------+-----+---------+----------------+
| idclass_has_student | int(11) | NO | PRI | NULL | auto_increment |
| class_idclass | int(11) | NO | MUL | NULL | |
| student_idstudent | int(11) | NO | MUL | NULL | |
| date_enrolled | varchar(45) | YES | | NULL | |
| grade | double | YES | | NULL | |
+---------------------+-------------+------+-----+---------+----------------+
select * from class_has_student;
+---------------------+---------------+-------------------+---------------+-------+
| idclass_has_student | class_idclass | student_idstudent | date_enrolled | grade |
+---------------------+---------------+-------------------+---------------+-------+
| 1 | 1 | 1 | 2012-09-04 | 0 |
| 2 | 1 | 2 | 2012-09-11 | 0 |
| 3 | 2 | 1 | 2012-09-14 | 0 |
+---------------------+---------------+-------------------+---------------+-------+
classhasstudent.php
<?php
class Model_ClassHasStudent extends Model_Table {
public $table='class_has_student';
public $entity_code='class_has_student';
public $id_field='idclass_has_student';
function init(){
parent::init();
$this->hasOne('Class','class_idclass','idclass', 'class_name');
$this->hasOne('Student', 'student_idstudent', 'name', 'student_name');
$this->addField('date_enrolled')->type('date');
$this->addField('grade');
}
}
mysql “subject” table
+--------------+-------------+------+-----+---------+----------------+
| Field | Type | Null | Key | Default | Extra |
+--------------+-------------+------+-----+---------+----------------+
| idsubject | int(11) | NO | PRI | NULL | auto_increment |
| name | varchar(45) | YES | | NULL | |
| subject_code | varchar(45) | YES | | NULL | |
| semester | varchar(45) | YES | | NULL | |
| description | blob | YES | | NULL | |
+--------------+-------------+------+-----+---------+----------------+
select * from subject;
+-----------+-----------+--------------+----------+--------------------------+
| idsubject | name | subject_code | semester | description |
+-----------+-----------+--------------+----------+--------------------------+
| 1 | Maths | mat101 | 1 | Mathematics and numbers. |
| 2 | English | enh101 | 1 | English and languages. |
| 3 | Chemistry | chm101 | 2 | Inorganic chemistry. |
+-----------+-----------+--------------+----------+--------------------------+
subject.php
<?php
class Model_Subject extends Model_Table {
public $entity_code='subject';
public $id_field='idsubject';
function init(){
parent::init();
$this->addField('name');
$this->addField('subject_code');
$this->addField('semester');
$this->addField('description');
}
}
Lister
<?php
// Lister class for displaying classes that a student attends.
class StudentClasses extends Lister {
function init(){
parent::init();
}
// Override defaultTemplate function.
function defaultTemplate(){
return array('view/class_info');
}
}
Templates
/templates/default/view/student_details.html
<div id="<?$_name?>" class="projectinfo">
<table class="student">
<tr><td id="property">Student Name</td><td id="value"> <?$name?> </td></tr>
<tr><td id="property">Student ID</td> <td id="value"><?$student_id?></td></tr>
</table>
</div>
<h2>Enrolled classes</h2>
<?ClassList?>
<?/?>
/templates/default/view/class_info.html
<dl id="<?$_name?>" class="<?$class?>">
<dt><?$subject_name?></dt>
<dd><?$date_start?></dd><dd><?$date_start?></dd>
</dl>
Pages
<?php
class page_TestClasses extends Page {
function init() {
parent::init();
$this->api->auth->check();
$this->api->stickyGET('id');
}
// Called only once.
function initMainPage(){
$view=$this->add('View',null,null,array('view/student_details'));
// $student = $this->add('Model_Student')->loadAny();
$student = $this->add('Model_Student')->loadAny();
// $student_detail= $student->ref('ClassHasStudent')->debug();
// select `idclass_has_student`,`class_idclass`,(select `idclass` from `class` where `class_has_student`.`class_idclass` = `class`.`idclass` ) `class_idclass_2`,`student_idstudent`,(select `name` from `student` where `class_has_student`.`student_idstudent` = `student`.`idstudent` ) `student_name`,`date_enrolled`,`grade` from `class_has_student` where `class_has_student`.`student_idstudent` = "1"
+---------------------+---------------+-----------------+-------------------+--------------+---------------+-------+
| idclass_has_student | class_idclass | class_idclass_2 | student_idstudent | student_name | date_enrolled | grade |
+---------------------+---------------+-----------------+-------------------+--------------+---------------+-------+
| 1 | 1 | 1 | 1 | Tom | 2012-09-04 | 0 |
| 3 | 2 | 2 | 1 | Tom | 2012-09-14 | 0 |
+---------------------+---------------+-----------------+-------------------+--------------+---------------+-------+
// USING $this->hasOne('Class','class_idclass','idclass', 'class_name'); in ClassHasStudent
// select `idclass_has_student`,`class_idclass`,(select `idclass` from `class` where `class_has_student`.`class_idclass` = `class`.`idclass` ) `class_name`,`student_idstudent`,(select `name` from `student` where `class_has_student`.`student_idstudent` = `student`.`idstudent` ) `student_name`,`date_enrolled`,`grade` from `class_has_student` where `class_has_student`.`student_idstudent` = "1";
+---------------------+---------------+------------+-------------------+--------------+---------------+-------+
| idclass_has_student | class_idclass | class_name | student_idstudent | student_name | date_enrolled | grade |
+---------------------+---------------+------------+-------------------+--------------+---------------+-------+
| 1 | 1 | 1 | 1 | Tom | 2012-09-04 | 0 |
| 3 | 2 | 2 | 1 | Tom | 2012-09-14 | 0 |
+---------------------+---------------+------------+-------------------+--------------+---------------+-------+
$student_detail= $student->ref('ClassHasStudent')->ref('class_idclass')->debug();
// select `idclass`,`subject_idsubject`,(select `name` from `subject` where `class`.`subject_idsubject` = `subject`.`idsubject` ) `subject_idsubject_2`,`date_start`,`date_end`,`max_students` from `class`
+---------+-------------------+---------------------+------------+------------+--------------+
| idclass | subject_idsubject | subject_idsubject_2 | date_start | date_end | max_students |
+---------+-------------------+---------------------+------------+------------+--------------+
| 1 | 2 | English | 2012-09-10 | 2012-09-30 | 10 |
| 2 | 1 | Maths | 2012-09-08 | 2012-09-30 | 30 |
| 3 | 3 | Chemistry | 2012-10-01 | 2012-10-31 | 35 |
| 4 | 2 | English | 2012-09-19 | 2012-09-29 | 10 |
+---------+-------------------+---------------------+------------+------------+--------------+
// Add Lister object to view, using LibraryList template spot.
$ClassList = $view->add('StudentClasses', null, 'ClassList');
$view->setModel( $student );
$ClassList->setModel( $student_detail );
}
}
I also modified Table::hasOne() to the following, where hasOne can set the dereferenced_field variable.
/atk4/lib/Model/Table.php
/** Defines one to many association */
function hasOne($model,$our_field=null,$display_field=null,$deref_field_name=null){
if(!$our_field){
if(!is_object($model)){
$tmp=preg_replace('|^(.*/)?(.*)$|','\1Model_\2',$model);
$tmp=new $tmp; // avoid recursion
}else $tmp=$model;
$our_field=($tmp->table).'_id';
}
$r=$this->add('Field_Reference',$our_field);
$r->dereferenced_field=$deref_field_name;
$r->setModel($model,$display_field);
return $r;
}
Update 1
Changing the above example to the design specified in the video produces the code below:
student.php
<?php
class Model_Student extends Model_Table {
public $table='student';
public $entity_code='student';
public $id_field='idstudent';
public $title_field='name';
function init(){
parent::init();
$this->addField('student_id')->caption('Student ID');
$this->addField('name')->caption('Name');
$this->hasMany('ClassJoinClassHasStudent');
}
}
ClassJoinClassHasStudent.php
class Model_ClassJoinClassHasStudent extends Model_Class {
function init(){
parent::init();
$chs = $this->join('class_has_student.class_idclass','idclass');
// Import fields from ClassHasStudent
$chs->addField('date_enrolled');
$chs->addField('grade');
$chs->hasOne('Class'); // use id_class from CHS table.
}
}
However, I get the following error related to setting the master field in ClassJoinClassHasStudent. I’ve tried calling hasMany(‘ClassJoinClassHasStudent’, ‘student_idstudent’, ‘idstudent’), but the error is the same except it complains about student_idstudent instead of student_id.
BaseException
Child element not found
Additional information:
Raised by object: Object Model_ClassJoinClassHasStudent(studentenrol_testclasses_model_student_ClassJoinClassHasStudent_model_classjoinclasshasstudent)
element: student_id
Possible Actions:
Debug this Model
/home/user1/public_html/studentenrol/atk4/lib/BaseException.php:38
Stack trace:
/home/user1/public_html/studentenrol/atk4/lib/BaseException.php :38 BaseException BaseException->collectBasicData(Null, 1, 0)
/home/user1/public_html/studentenrol/atk4/lib/AbstractObject.php :292 BaseException BaseException->__construct("Child element not found")
/ : studentenrol_testclasses_model_student_ClassJoinClassHasStudent_model_classjoinclasshasstudent Model_ClassJoinClassHasStudent->exception("Child element not found")
/home/user1/public_html/studentenrol/atk4/lib/Model/Table.php :87 Loggercall_user_func_array(Array(2), Array(1))
/home/user1/public_html/studentenrol/atk4/lib/AbstractObject.php :202 studentenrol_testclasses_model_student_ClassJoinClassHasStudent_model_classjoinclasshasstudent Model_ClassJoinClassHasStudent->exception("Child element not found")
/home/user1/public_html/studentenrol/atk4/lib/Model/Table.php :259 studentenrol_testclasses_model_student_ClassJoinClassHasStudent_model_classjoinclasshasstudent Model_ClassJoinClassHasStudent->getElement("student_id")
/home/user1/public_html/studentenrol/atk4/lib/Model/Table.php :321 studentenrol_testclasses_model_student_ClassJoinClassHasStudent_model_classjoinclasshasstudent Model_ClassJoinClassHasStudent->addCondition("student_id", "1")
/home/user1/public_html/studentenrol/atk4/lib/SQL/Many.php :48 studentenrol_testclasses_model_student_ClassJoinClassHasStudent_model_classjoinclasshasstudent Model_ClassJoinClassHasStudent->setMasterField("student_id", "1")
/home/user1/public_html/studentenrol/atk4/lib/Model/Table.php :243 studentenrol_testclasses_model_student_ClassJoinClassHasStudent SQL_Many->ref(Null)
/home/user1/public_html/studentenrol/page/testclasses.php :93 studentenrol_testclasses_model_student Model_Student->ref("ClassJoinClassHasStudent")
/home/user1/public_html/studentenrol/atk4/lib/ApiFrontend.php :93 studentenrol_testclasses page_TestClasses->initMainPage()
/home/user1/public_html/studentenrol/atk4/lib/ApiWeb.php :332 studentenrol Frontend->layout_Content()
/home/user1/public_html/studentenrol/atk4/lib/ApiFrontend.php :33 studentenrol Frontend->addLayout("Content")
/home/user1/public_html/studentenrol/atk4/lib/ApiWeb.php :208 studentenrol Frontend->initLayout()
/home/user1/public_html/studentenrol/index.php :24 studentenrol Frontend->main()
I have recreated your example and changed the code like this:
Basically you must start with the model you are willing to display. Because you want to list classes, you should go for Model_Class. Then you join the model with the many-to-many table and define the field from the other end (student_idstudent). Next you can use it in condition.
I also had to patch Model_Table to allow 4th argument for hasOne() to define dereferenced fields, so please update to the latest ATK4.
https://github.com/atk4/atk4-testsuite/commit/ccaef2c5e5841bb265001f00d832c3583a4cf722