I am learning the Model relationship types in cakephp.
I have built two tables and in one of the Table A,
I got these fields in it:
Table A {postID, topic, content}
Table B {replyID, content, postID}
And when I ran the web page, a bunch of error related to SQL popped up saying that
cakephp couldn't find post_id.
It is weird that I have already declared
the $primaryKey to be using postID in the tableA.php under Models folder,
but cakephp seemed want me to change the ID field to post_id instead of postID,
because the error disappeared after I have changed the primaryKey to post_id.
ANy ideas?
Cake expects your fields to be lower case, with words separated by underscores. See the CakePHP Model and Database Naming Conventions for more information.
By convention the field with the primary key is named id.
Related
I have a database with table Photos and table Categories. Each photo is related to one category by categoryId field.
What happens when I delete one category from Categories table? Will the photos with that category be updated with a null value in the categoryID? Or how will entity-framework react to this change?
Another question can I then reset with a mass-change the values of those categories in the photos table? And how can I do that?
hi if you have created relationship between table(using foreign key) then only the deletion of parent table will affect deletion of child table. if you just created table separately and managing relationship with your code then it will not affect the child table. if you are creating using model first approach in entity framework with specifying relation then relationship will be automatically created in backend.
their are four options available in sql on deletion of parent entity
1)No Action
2)Cascade
3)SET NULL
4)SET Default
to know how it will affect check this article
https://www.mssqltips.com/sqlservertip/2365/sql-server-foreign-key-update-and-delete-rules/
That would depend completely on how the ORM that is used defines the database model.
Assuming you use Entity Framework then you can define exactly how EF should react to that situation. In the DbContext you should find a OnModelCreating method in wich you can specify per table what restrictions you want on the table. There you can also define the behaviour of the OnDelete of a foreign key.
If you are not using EF but have your own or a different ORM then again, it depends on how that ORM is configured.
Simple check if you dont know about the used ORM is this: Does the field in the database have a foreign key and how is that configured? Also, is the field categoryID (as defined in the database) nullable? if so, then it apparently doesnt need the relation and shouldnt result in related deletes.
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
What is the right plural/singular table naming convention in CakePHP.
This:
posts
posts_pictures
posts_picture_captions <-- Not sure about this
Or this:
posts
posts_pictures
posts_pictures_captions <-- Not sure about this
I know CakePHP want the tables in alphabetical order but this should in this question ignored. Please only consider plural/singular table naming.
Cake Inflector Should do exactly what you are looking to do.
From the cakephp book:
Model class names are singular and CamelCased. Person, BigPerson, and
ReallyBigPerson are all examples of conventional model names.
Table names corresponding to CakePHP models are plural and
underscored. The underlying tables for the above mentioned models
would be people, big_people, and really_big_people, respectively.
You can use the utility library Inflector to check the singular/plural
of words. See the Inflector for more information.
Field names with two or more words are underscored: first_name.
Foreign keys in hasMany, belongsTo or hasOne relationships are
recognized by default as the (singular) name of the related table
followed by _id. So if a Baker hasMany Cake, the cakes table will
refer to the bakers table via a baker_id foreign key. For a table like
category_types whose name contains multiple words, the foreign key
would be category_type_id.
See http://book.cakephp.org/2.0/en/getting-started/cakephp-conventions.html#model-and-database-conventions
So at first, your "posts_pictures" table should be named "post_pictures".
As a result, neither of the two is correct. The correct name according to the cake naming conventions is "post_picture_captions".
I did a little research on tag clouds, and I ended up choosing a schema similar to the Wordpress one seen in this page: http://www.pui.ch/phred/archives/2005/04/tags-database-schemas.html
Currently, the tables that I have created is: Posts, PostsTagMaps, PostsTags
1) Would I need to create a table for PostsTagMaps even if I don't plan on using a controller?
2) A Post hasMany PostTagMaps. I'm not sure where should I be defining this relationship. I think it should be the Post model, but then I would have to join the PostsTags table to PostTagsMaps then join it to Posts, so I wanted to ask for some advice.
The easy solution is to follow Cake conventions (which will look very similar to the solution you linked to). You'll have three tables:
posts, tags, posts_tags
Then your Post model HABTM Tag model. The join table will automatically be used by Cake to save and retrieve the information. Check the book for more information on setting up your schema.
Cake is flexible enough where you can do it however you want, but if it's a basic sort of posts-tags relationship, the convention method is the way to go.
If you want to use a custom model/table like PostsTagMaps, then do this by using the 'with' key in your HABTM relationship definition. The 'with' key tells Cake to use a specific model (and therefore a specific table) instead of an automatically generated version. In this case, your tag model sounds like it's PostsTags and your HABTM table is PostsTagMaps, so the 'with' key on Post HABTM PostsTag would be PostsTagMap.
I'm trying to use EF to model an existing SQL database. The DB is multi-tenant by having a clientID column in every single table (I cannot change this). I have table structure like the following.
Table 'ItemID' columns:
ClientID (pk)
ItemID (pk)
ItemName
Table 'Items' columns:
ClientID (PK)
ItemID (PK) [FK to ItemID.ItemID]
Version (PK)
ItemAttribute1
ItemAttribute2
ItemAttribute3
The DB is designed to store previous versions (rows) of the 'Item' object, hence the 'Version' column and PK.
I am new to the EF and trying to adopt it for my project. However, it seems that EF cannot handle this situation very well. I am open to all ideas including using stored procedures or views instead of access tables directly from EF. What about getting rid of the PKs and using 'independant' relations instead?
One specific problem I ran into is that EF (at least the designer) requires all PKs in one table be mapped to all PK columns in any related table. This does not make sense to me, as the example I've given will never work given that constraint. I am trying to make Items inherit from ItemID. The error I get is:
Error 3003: Problem in mapping
fragments starting at line 170:All the
key properties (ItemID.ClientID,
ItemID.ItemID) of the EntitySet ItemID
must be mapped to all the key
properties (Items.ClientID,
Items.ItemID, Items.Version) of table
Items.
I have been looking up all I can find on this topic and nothing has answered these questions for me. I appreciate any help. Thanks.
The error that you are getting from your EDM is coming from the fact that EF supports inheritance only if both entities have the exact same primary keys (hence a one to one relationship on database) so you cannot have inheritance between these 2 entities according to the current schema.
However, I don't see a problem on having a One to Many association between ItemID and Items entities and I believe this is the default EF behavior when you update your model from the database.
Please have a look at this post for more info:
Entity Framework, TPT Inheritance