Virtual Fields and model aliases - cakephp

I'm newbie in cakephp and a I have the next problem:
Model: CostsCenter->Scholarship->ScholarshipsDetail
1. Virtual Field in Scholarship Model:
public $virtualFields = array(
'code' => "UPPER(CONCAT(SUBSTR(CostsCenter.name, 1, 3), '-',
Scholarship.selection_year, '-', SUBSTR(Country.name, 1, 3), '-',
Postulant.number))");
2. List all in the Controller from ScholarshipsDetail
$scholarships_detail = $this->ScholarshipsDetail->find('all',
array('contain' => array('Scholarship' => array('CostsCenter')),
'conditions' => array('ScholarshipsDetail.scholarship_id' => $scholarship_id)));
Then, I need list the ScholarshipsDetail, but I have the error:
Column not found: 1054 Unknown column 'CostsCenter.name' in 'field list'
I tried to apply "contain" in CostsCenter across Scholarship but the error still appears

The problem is that doing a find using containable does not select ScholarshipDetail JOIN Scholarship JOIN CostCenter.
If you look in the SQL debug output you will see that first it gets the ScholarshipDetail and Scholarship records, then it loops through these and adds the CostCenter records to the results array by doing individual selects on the CostCenter table.
Therefore the CostCenter fields are not available to use in the virtual field and the query fails. This link helps to explain this containable pitfall better.
If you really want to keep your virtual field, you should not use containable and set up the query using manual joins instead.
However, as you are going to frequently have this kind of problem because your virtual field references different models, it would be a better idea to create a real field instead. Try something like this:
Create a field called code in the scholarships table
Create a function eg updateCode() in the Scholarship model that formulates the code by selecting the correct information from the various tables and then updates the code field in the scholarships table.
Call this function from the controller after any action that could affect the code, eg when a Scholarship record is edited (or consider putting it in the afterSave callback of the Scholarship model)

Related

Cakephp contains association when using matching()

In my project I have the following tables: Messages, Recipients, Groups and Users. A Message has many Recipients, and a Recipient has one Group and one User.
In my RecipientsTable::beforeFind I have some code to automatically contain Groups and Users for Recipient finds, since I always need to access those associations.
public function beforeFind($event, $query, $options, $primary) {
return $query->contain([
'Groups',
'Users',
]);
}
I don't know if this is a bad design decision but it has worked for me so far.
The problem has come now that I'm trying to filter messages by group, and I tried doing so by using the matching function:
$possible_groups = [1,2,3]; //just an example
$query->matching('Recipients', function($q) use ($possible_groups){
return $q->where(['Recipients.group_id IN' => $possible_groups]);
});
When I execute the query, I get the following error:
Messages is not associated with Groups
Is there any way to keep my beforeFind like that and be able to use matching? Or, is there a better way to automatically load associations without using beforeFind?
TL;DR: A hasMany B, B hasOne C. If a query on table A uses matching on table B and table B's beforeFind uses contain to load C, C ends up contained onto the original query (of A) and the execution fails since A is not associated with C.
Use table classes to load Table associations automatically. Like using hasMany(), hasOne(), belongsTo(), belongsToMany() in necessary table classes.
Official documentation:
https://book.cakephp.org/3.0/en/orm/associations.html
Table files should be in the Table folder inside the Model folder like src\Model\Table.

CakePHP 2 - Deriving table name of model within Behavior

Whats the usual practice in getting a behavior (linked to multiple models) to build filters for SQL queries, and then read the table that belongs to that model?
I have a Behavior function which is meant to do a database query with certain SQL conditions. I currently pass in the $this->request->data.
I have issues building the SQL conditions because i'm not sure how to derive the name of the table (that corresponds to the model). See below for example, I want to change "BillingCenterDetail" which is the table name (and also the model name), to something generic I can use across different models. I want this table name to be derived automatically based on the model name. I'm not sure if i can use the $model reference for that.
public function saveWithTimeConstraintCheck(Model $model, $data) {
//FIND ALL RECORDS THAT OVERLAP
$overlapfilter = array(
'BillingCenterDetail.billing_center_id =' => $data['BillingCenterDetail']['billing_center_id'],
'BillingCenterDetail.startdate <=' => $data['BillingCenterDetail']['enddate'],
'BillingCenterDetail.enddate >=' => $data['BillingCenterDetail']['startdate']
);
... after building the filter, I can use $model->find to execute the query, this should be OK because its generic.
$overlapresults = $model->find('all', array('conditions' => $overlapfilter));
I've answered my own question.
And actually to build filter conditions, I needed name of the model, not the name of the table, because the name of the table is a plural name with the "S" at the end.
I used
$Model->name
From:
CakePHP: get current model name in a controller
For table names i found out u can also use
$this->Model->table
cakephp - get table names and its column details

CakePHP containable behaviour not firing

First time using Cake and its containable behaviour, but it's not working as expected ... or at all.
I'm trying to obtain a list of accessories for a product. Product model HABTM products (alias 'ProductRelation'). Join table is products_products which has two product ids - product_id and related_id. It's against this I want to pull the list of accessories (products driven from the related_id column) for a given product_id
In my Product model, I've added $actsAs = array('Containable');
And in my controller, a quick test of containable using reference from the cookbook fails to contain products at all, even without conditions.
debug($this->Product->find('all', array('contain' => 'ProductRelation')));
.. returns an array of every product in the db, with ALL related models - images, content tabs, ratings, reviews, pricing, etc I haven't tried applying any 'conditions' against this because the call as written should limit data to the product and it's ProductRelation data, according to the cookbook ...
Any tips?
It seems like you have recursive on. Try using the following:
debug($this->Product->find('all', array(
'contain' => 'ProductRelation',
'recursive' => -1
)));
If that works for you, you should start adding containable to the AppModel class and setting the recursive property to -1. This will ensure you only ever get the results you request.
NB: Cake does not join for HABTM, so you can not use ProductRelation in any conditions.

Possible to have association or not based on main model's data?

I have a nodes table (Node model). I'd like it to be associated to different data types, but only if one if it's field is set to 1.
Example:
My nodes table has a data_article field (tinyint 1). I only want the Node to $hasMany Article IF that field is a 1.
I tried this:
public $hasMany = array(
'Article' => array(
'conditions' => array('Node.data_articles' => '1')
),
);
But I get an error:
Column not found: 1054 Unknown column 'Node.data_articles' in 'where
clause'
Because the association is doing the Article find in it's own query:
SELECT `Article`.`id`, `Article`.`title`, `Article`.`node_id`, ...more fields...
FROM `mydatabase`.`articles` AS `Article`
WHERE `Node`.`data_artiles` = '1'
AND `Article`.`node_id` = ('501991c2-ae30-404a-ae03-2ca44314735d')
Obviously that doesn't work, since the Node table isn't being Joined at all in this query.
TLDR:
Is it possible to have associations or not based on a field in the main model? If not, how else can I keep different data types in multiple tables, and not have to query them all every time?
I don't think that there's a standard way to do this with CakePHP (at least I can't imagine a way). What definitely is possible would be binding associated models dynamically.
So you might query your model without associations by passing the recursive parameter as -1 to the find() method and based on the result unbind the associated models dynamically. Afterwards you would have to query again, for sure. You might build a behavior out of this to make it reusable.
A quite elegant solution would be possible, if Cake could make a two-step query with a callback after the main model was queried, but before associated models are queried, but this isn't possible at the moment.
Edit: There might be a non-Cake way to archieve this more performantly with a custom Query including IF-statements, but I'm not the SQL expert here.
You should do it from the other side:
public $belongsTo = array(
'Node' => array(
'conditions' => array('Node.data_articles' => '1')
),
);

How do I join two tables in a third n..n (hasAndBelongsToMany) relationship in CakePHP?

I have a n...n structure for two tables, makes and models. So far no problem.
In a third table (products) like:
id
make_id
model_id
...
My problem is creating a view for products of one specifi make inside my ProductsController containing just that's make models:
I thought this could work:
var $uses = array('Make', 'Model');
$this->Make->id = 5; // My Make
$this->Make->find(); // Returns only the make I want with it's Models (HABTM)
$this->Model->find('list'); // Returns ALL models
$this->Make->Model->find('list'); // Returns ALL models
So, If I want to use the list to pass to my view to create radio buttons I will have to do a foreach() in my make array to find all models titles and create a new array and send to the view via $this->set().
$makeArray = $this->Make->find();
foreach ($makeArray['Model'] as $model) {
$modelList[] = $model['title'];
}
$this->set('models', $models)
Is there any easier way to get that list without stressing the make Array. It will be a commom task to develops such scenarios in my application(s).
Thanks in advance for any hint!
Here's my hint: Try getting your query written in regular SQL before trying to reconstruct using the Cake library. In essence you're doing a lot of extra work that the DB can do for you.
Your approach (just for show - not good SQL):
SELECT * FROM makes, models, products WHERE make_id = 5
You're not taking into consideration the relationships (unless Cake auto-magically understands the relationships of the tables)
You're probably looking for something that joins these things together:
SELECT models.title FROM models
INNER JOIN products
ON products.model_id = models.model_id
AND products.make_id = 5
Hopefully this is a nudge in the right direction?
Judging from your comment, what you're asking for is how to get results from a certain model, where the condition is in a HABTM related model. I.e. something you'd usually do with a JOIN statement in raw SQL.
Currently that's one of the few weak points of Cake. There are different strategies to deal with that.
Have the related model B return all ids of possible candidates for Model A, then do a second query on Model A. I.e.:
$this->ModelB->find('first', array('conditions' => array('field' => $condition)));
array(
['ModelB'] => array( ... ),
['ModelA'] => array(
[0] => array(
'id' => 1
)
)
Now you have an array of all ids of ModelA that belong to ModelB that matches your conditions, which you can easily extract using Set::extract(). Basically the equivalent of SELECT model_a.id FROM model_b JOIN model_a WHERE model_b.field = xxx. Next you look for ModelA:
$this->ModelA->find('all', array('conditions' => array('id' => $model_a_ids)));
That will produce SELECT model_a.* FROM model_a WHERE id IN (1, 2, 3), which is a roundabout way of doing the JOIN statement. If you need conditions on more than one related model, repeat until you have all the ids for ModelA, SQL will use the intersection of all ids (WHERE id IN (1, 2, 3) AND id IN (3, 4, 5)).
If you only need one condition on ModelB but want to retrieve ModelA, just search for ModelB. Cake will automatically retrieve related ModelAs for you (see above). You might need to Set::extract() them again, but that might already be sufficient.
You can use the above method and combine it with the Containable behaviour to get more control over the results.
If all else fails or the above methods simply produce too much overhead, you can still write your own raw SQL with $this->Model->query(). If you stick to the Cake SQL standards (naming tables correctly with FROM model_as AS ModelA) Cake will still post-process your results correctly.
Hope this sends you in the right direction.
All your different Make->find() and Model->find() calls are completely independent of each other. Even Make->Model->find() is the same as Model->find(), Cake does not in any way remember or take into account what you have already found in other models. What you're looking for is something like:
$this->Product->find('all', array('conditions' => array('make_id' => 5)));
Check out the Set::extract() method for getting a list of model titles from the results of $this->Make->find()
The solution can be achieved with the use of the with operation in habtm array on the model.
Using with you can define the "middle" table like:
$habtm = " ...
'with' => 'MakeModel',
... ";
And internally, in the Model or Controller, you can issue conditions to the find method.
See: http://www.cricava.com/blogs/index.php?blog=6&title=modelizing_habtm_join_tables_in_cakephp_&more=1&c=1&tb=1&pb=1

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