I was wondering if this is possible to do with a has many through
contents orgs folders
id id id
name name title
link
join table - folder_elements
id
element_id
order
contents has many folders through folder_elements
orgs has many folders through folder_elements
So my question is, is it possible to use element_id to store the content.id or the org.id ?
Alex
What you're describing is a sort of HABTM (HasAndBelongsToMany) association. You could define the inter-model associations as you suggest, but there's a pretty significant design flaw: how would you account for a situation where the same ID is used for an orgs record and a contents record, and wish to associate them with the same folder record? It would be impossible to differentiate between the two in your joining table.
There are a number of ways to work around this, but they require more program logic or a more disorganised database schema that presents challenges in maintainability.
The more elegant, robust solution is to rationalise your database structure. If there's no pressing need to have One Join Table to Rule Them All, you could design your model associations like this:
Content hasMany ContentsFolder belongsTo Folder
Folder hasMany ContentsFolder belongsTo Content
Org hasMany OrgsFolder belongsTo Folder
Folder hasMany OrgsFolder belongsTo Org
This is the internal structure of a HABTM association defined explicitly so you can define fields in the joining table. Your contents and folders tables would remain the same, but your two joining tables would look like:
contents_folders
-> id
-> content_id
-> order
orgs_folders
-> id
-> org_id
-> order
Unfortunately, yes, this would require defining five models instead of three, but such are the limitations of CakePHP's object-relational modelling.
Related
How i do a crud with a relationship between a user and services order? With the code, i can't add users in a team for service order. When cakebake, the controller TeamHasUsersController is created, but the form add don't have any field.
The crud has generated with cake bake.
In service_orders: change requester_users_id into user_id, the icon in front of the field will change to a red key (foreign key). Cake conventions need a foreignkey to be named [model]_id.
The name of table with associations should be "team_users".
Three database tables are required for a BelongsToMany association. In the example above we would need tables for articles, tags and articles_tags. The articles_tags table contains the data that links tags and articles together. The joining table is named after the two tables involved, separated with an underscore by convention. In its simplest form, this table consists of article_id and tag_id.
habtm relationship
Cake newb here.
I have two tables. Users and Events. An user can subscribe to Multiple events.
What is the best way to implement this?
Do I have to create another table and link them or is there any other better approach.
If I do create a new table, how do i link them in cake model?
As said by jQuery.PHP.Magento.com you should use HABTM relationship but the name of the third table should be events_users because the table names should be in alphabetical order.
From the doc:
Table names are in alphabetical order by convention. It is possible to
define a custom table name in association definition.
You should use HABTM relationship.
Reason
See users will subscribe to Multiple events and
One event have multiple users subscribed for.
So this is two way relationship. Therefore you need following tables
users : To store user's data,
events : To store user's data,
events_users : To store Which user joined Which event and Vice versa(Events with n number of users)
So users_events will have 2 fields user_id , event_id , both are foreign keys and here you dont need primary key in HABTM relationship.
My data structure is as follows:
Company hasMany Regions
Region hasMany Markets
Market hasMany Stores
Store hasMany Employees
I also have the appropriate belongsTo where necessary.
I used foreign keys for associations. For example, each store has market_id.
When I delete a Company record, the correct Region is also deleted. However, it occurred to me that I also need all associated Markets, Stores, and Employees to be deleted. Or if I deleted a Market, I would need all Stores and Employees deleted.
What is the most appropriate manner of accomplishing this?
Would I add additional foreign keys to the tables? For example, would Stores need region_id and company_id in addition to market_id?
Use dependent association:
http://book.cakephp.org/2.0/en/models/associations-linking-models-together.html#hasmany
dependent: When dependent is set to true, recursive model deletion is
possible. In this example, Comment records will be deleted when their
associated User record has been deleted.
You don't need to add the additional foreign keys.
I have a database with a "users" table containing data about my users. Each user is to be linked to a company or a college. I wish to have two separate tables "college" and "company" each with a field "ID". So how do I link each record in the users table to either a company or a college?
The basic thing is that I wish to establish an "OR" relationship in the database.
You can use subtype/super-type relationship. Keep all common fields in the organization table. College and company tables contain only fields specific to those entities.
You could use an 'institution' or 'organisation' lookup table, with a structure something like
InstitutionId[PK], InstitutionType, LookupKey
where LookupKey is the PK to either Company or College.
Or,
InstitutionId[PK], CompanyId[FK], CollegeId[FK]
In both cases you link from user to institution, then onto Company and/or College.
I personally prefer the second option, because it allows you to easily validate the FK relationship and also allows (if applicable) for a user to be a member of a company and/or a college.
I would create relationtables. UserCollege and UserCompany. This way you are even able to have users that are linked to both if needed in the future. If not you simply just create a relationrecord on one of the both
I have CakePHP app in which I'd like to attach gallery to multiple resources. Let's say I've got artists, each one has own gallery. I've got articles, every article has some images attached to it and so on. Now I set up tables like this:
Artists hasMany Artistimages, fields in artistimages table are: id, artist_id, filename, filetype, filesize etc.
Articles hasMany Articleimages, fields in articleimages table are: id, article_id, filename, filetype, filesize etc.
...but this is not how it should be, I think.
Is there possibility to have one table called for example uploads which will contain all images with foreign key pointing to resource its reffering to? How to tell CakePHP which image is coming from which resource?
I'd recommend using the Polymorphic Behavior. I often do this for a Binary model which covers images, documents, etc. These represent the physical files that can be associated with any number of models (photos, applicants, etc.).
The gist of a polymorphic relationship is that the table has 2 additional fields. One field that indicates the name of the model being associated (e.g. Photo, Applicant, etc.) and another for the foreign key value (i.e. the id field in the photos table, for example).
If this was me, I would have an images table, then I would have the Artist and Article hasAndBelongsToMany to Image.
Your HABTM would then have a two join tables artists_images and articles_images, then with any luck, Cake will write into these join tables the relationships between each. So you should end up with the correct things associated with the correct images.
By using the HABTM, you can even have one image associated with an Article and Artist, and the same image associated more than once if you need to.
Hope this makes sense, there is more info on HABTM in the book, http://book.cakephp.org/view/83/hasAndBelongsToMany-HABTM
For all of you looking for working solution using polymorphic behavior and MeioUpload, check out this. I'm using it right now and it seems to work fine.