My question is in relation this this answer.
https://stackoverflow.com/a/8773953/1297775
I have read at many places, what #deceze put as:
"To be quite honest, for any halfway complex application, relying on Cake's automagic handling of HABTM relationships can get quite fragile and hard to debug, so I always manage HABTM records myself."
Even the CakePHP book hints at it http://book.cakephp.org/2.0/en/models/saving-your-data.html#what-to-do-when-habtm-becomes-complicated
I want to ask, that when he says he 'manages' this HABTM records himself, does he...
1) Not create the HABTM relations in the models at all and create a model for the join table
OR
2) Create the HABTM relations in the models, but does not use it in the controller code by just using $this->FirstModel->JoinModel->saveAll($someData);
Thanks
Basically you need use a hasManyThrough relationship, which is essentially a HABTM setup manually which allows you to add extra data to the relationship (such as created/expiry dates). It's quite simple, you just need to create a model to join them and use the normal belongsTo and hasMany properties in the model, here is a simple user/membership/course setup:
class User extends AppModel {
public $hasMany = array('Membership');
}
class Course extends AppModel {
public $hasMany = array('Membership');
}
class Membership extends AppModel {
public $belongsTo = array('User', 'Course');
}
The only fields (at minimum) the memberships table needs is course_id and user_id.
You can now operate on the Membership model as a normal model, without Cake treating it as HABTM and using its auto-magic whenever you save records. You can also use cool counterCaches on the membership model to count how many users a course has etc.
Related
I am having trouble understanding how the model class can create a table in the database.
If I wanted a table with fields users and password, wherein CakePHP do I define these fields? It seems like, in the examples I've seen, that these fields are validated in the model. But where are they defined or initialized?
Thanks.
CakePHP models don't create the database tables for you. They are a means of accessing existing tables that you have created. If you follow CakePHP's naming conventions the models just automatically know which tables they relate to; singular CamelCased model names relate to plural snake_cased tables.
To create your database tables you can either do this manually, or use CakePHP schemas to manage the database structure. There's also the excellent CakeDC migrations plugin for managing changes to the database structure.
CakePHP Schema management
CakeDC Migrations plugin
When a model is used in CakePHP it can determine the fields that belong to the model by running a SQL DESCRIBE query on the database table. This is done using the Model::schema() method. Cake caches the query results so that it doesn't need to keep querying the database for this.
Yes , sure , You can control database's table with its fields ,Model name should be the same of table name , in any controller you can load
$this->loadModel('SomeModel')
$mydata=$this->tableName->find('all');
$myuse =$this->set('myuse' , $mydata);
in your view , The name of view should be the same of your Controller's function name:
<h1> <?php echo $myuse['tableName']['fieldName]; ?></h1>
It not required to same name model as database table
like my table name is users and i create a model User
then you can define this table with User model in model > User.php
<?php
App::uses('AppModel', 'Model');
class User extends AppModel
{
public $name = 'User';
public $useTable = 'users';
public $primaryKey = 'id';
}
I have an idea of how to do this but it doesn't seem like proper convention. I have a Submission model and a Revision model each with their similarly named tables. Each Submission can have one or more Revisions associated to it in a $hasMany relationship. The Revision model hence has a $belongsTo relationship linking back to the Submission.
In addition to having this relationship, the Submission model needs to have another association (called activeRevision) to a particular Revision in a $hasOne style of relationship. However, the $hasOne type requires the foreign key to be in the Revision table. I want it to be in the Submission table, so I don't need to query all of the Submission's Revisions to find the active one. I realized just specifying a $belongsTo relationship in the Submission would do what I want, but this feels wrong to me as now the two models "belong to eachother".
Is there a better way to go about this?
I wouldn't worry too much because of the 'naming' of the relation. By having the foreign key of the Revision inside the Submission table, CakePHP is, in fact, right that you've created a 'belongsTo' relation.
Although not strictly the 'right' (?) relation, in this situation, this looks like it's an easy way to achieve what you want. Just be sure to add an additional condition to your relation to prevent that a revision of another submission can be set as the current revision, i.e.;
public $belongsTo = array(
'Revision' => array(
'conditions' => array(
'Revision.submission_id = Submission.id',
)
)
);
However, make sure to add a proper comment in your code to prevent confusion if you're (or somebody else is) looking at your code in a later stage. (e.g. "note: using belongsTo relation, because its easier to maintain)
If you really want to convert it to a hasOne relation, you'll have to add an additional column to the 'Revisions' table, for example 'is_curreny_revision'. However, you will also need to be sure that only one revision of a submission can be set to be the current revision.
If you're using PostgreSQL, this can be achieved using a 'partial unique' index (see this question on StackOverflow; PostgreSQL: Conditional unique constraint). MySQL does not support partial indexes, so you're out of luck there
I have two models: Store and Review. Users of my site can leave a review on a store. In my database, I have a join table, reviews_stores that associates a review with a store.
How do I link my models? I assume a Store should haveMany Review, and a Review should belong to a Store, but the join table is causing issues with CakePHP as CakePHP is assuming my reviews table has a column called store_id.
The reason I'm using a join table is because many parts of my site can be reviewed. For example, brands. A new Review record will be created and a record will be inserted into a brands_reviews table to associate the two records.
Any help would be much appreciated.
Why are you not simply using one Review model and a reviews table with a field "foreign_key" and another field "model"? By this you do not need to duplicate tables and inherit or duplicate models. This will also remove the need for a join table.
If you want to continue to use your db design then you'll have to use a HABTM association over the hasMany association. But even in the case you want to keep that jointable, again, you can use the foreign_key/model and simply have one join table and one reviews table.
By the way, your join table review_store does not follow the conventions, it should be reviews_stores. But then it differs to the schema you've used for brands_reviews. ;)
Seems to me it isn't a many-many relationship but a grouped 1-many relationship. Id lose the join tables and simply have an extra table outlining which 'group' the review belongs to. So the review table would have review_id, link_id(the foreign key for the relevant brand or store), review_type_id(foreign key depicting whether the review is for a brand or store and so on). Then the review_type table only needs to have review_type_id, review_type(varchar).
There's no need for all the join tables for each model you can review, simple store the model name itself in a field in the Review table.
Setup your relationship like so:
class Store extends AppModel {
public $hasMany = array(
'Review' => array('conditions' => array('Review.model' => 'Store')
);
}
You can then do this with as many extra models as you like without having to touch the database.
Basically I would like to recreate this in CakePHP:
Many to many relationships with additional data on the relationship
or in other words, my intermediary table to have extra fields defining the type of relationship.
How do I set this up in CakePHP?
You can use as example:
model company:
id
name
person_id
model person:
id
name
model company_person:
company_id
person_id
position
thanx
if you want to have additional data in HABTM, use 2 hasMany relationships instead. So if A HABTM B, then set it up as: A hasMany A_B, B hasMany A_B, A_B belongsTo A, A_B belongsTo B. AFAIK, Cake support for HABTM is not very flexible.
class Person extends AppModel {
...
$hasAndBelongsToMany = array('Company', array('with' => 'CompanyPerson'));
....
}
I have a bunch of models that I'm going to be creating, and these models will have different types of categories that they can belong to. For example, one model will HABTM one set of categories, another model will HABTM another set.
I've come up with one idea - creating a model called Category, and having a categories table with a 'model' field, that contains the name of the model that this category has a HABTM relationship with. Then the other models would have something like this:
public $hasAndBelongsToMany = array(
'Category'=>array(
'conditions'=>array(
'Category.model'=>'Modelname'
)
)
)
This seems OK but
this code will be repeated in every model which seems silly and
some categories will apply to several models, so there would be duplicate database entries for those categories.
Is there a better way? Thanks for your help!
You can use one category model and add a model field to the category model to specify the related model. So you can use different models with one category model... Like you said...
I think this is a good idea.