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• cakephp hasMany through and multiselect form

  - by Zoran Kalinic

  I'm using cakephp 2.2.2 and I have a problem with the editing view Models and relationships are: Person hasMany OrganizationPerson Organization hasMany OrganizationPerson OrganizationPerson belongs to Person,Organization A basic hasMany through relationship as found within cake documentation. Tables are: people (id,...) organizations (id,...) organization_people (id, person_id,organization_id,...) In the person add and edit forms there is a select box allowing a user to select multiple organization. The problem I have is, when a user edits an existing person, the associated organizations aren't pre-selected. Here is the code in the PeopleController: $organizations = $this->Person->OrganizationPerson->Organization->find('list'); $this->set(compact('organizations')); Related part of the code in the People/edit code looks like: $this->Form->input('OrganizationPerson.organization_id', array('multiple' => true, 'empty' => false)); This will populate the select field, but it does not pre-select it with the Person's associated organizations. Format and content of the $this-data: Array ( [Person] => Array ( [id] => 1 ... ) [OrganizationPerson] => Array ( [0] => Array ( [id] => 1 [person_id] => 1 [organization_id] => 1 ... ) [1] => Array ( [id] => 2 [person_id] => 1 [organization_id] => 2 ... ) ) ) What I have to add/change in the code to get pre-selected organizations? Thanks in advance!

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• How do you unit-test a method with complex input-output

  - by Dan

  When you have a simple method, like for example sum(int x, int y), it is easy to write unit tests. You can check that method will sum correctly two sample integers, for example 2 + 3 should return 5, then you will check the same for some "extraordinary" numbers, for example negative values and zero. Each of these should be separate unit test, as a single unit test should contain single assert. What do you do when you have a complex input-output? Take a Xml parser for example. You can have a single method parse(String xml) that receives the String and returns a Dom object. You can write separate tests that will check that certain text node is parsed correctly, that attributes are parsed OK, that child node belongs to parent etc. For all these I can write a simple input, for example <root><child/></root> that will be used to check parent-child relationships between nodes and so on for the rest of expectations. Now, take a look at follwing Xml: <root> <child1 attribute11="attribute 11 value" attribute12="attribute 12 value">Text 1</child1> <child2 attribute21="attribute 21 value" attribute22="attribute 22 value">Text 2</child2> </root> In order to check that method worked correctly, I need to check many complex conditions, like that attribute11 and attribute12 belong to element1, that Text 1 belongs to child1 etc. I do not want to put more than one assert in my unit-test. How can I accomplish that?

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• Query returning related assets

  - by GMo

  I have 2 tables, one is an assets table which holds digital assets (e.g. article, images etc), the 2nd table is an asset_links table which maps 1-1 relationships between assets contained within the assets table. Here are the table definitions: Asset +---------------+--------------+------+-----+---------+----------------+ | Field | Type | Null | Key | Default | Extra | +---------------+--------------+------+-----+---------+----------------+ | id | int(11) | NO | PRI | NULL | auto_increment | | source | varchar(255) | YES | | NULL | | | title | varchar(255) | YES | | NULL | | | date_created | datetime | YES | | NULL | | | date_embargo | datetime | YES | | NULL | | | date_expires | datetime | YES | | NULL | | | date_updated | datetime | YES | | NULL | | | keywords | varchar(255) | YES | | NULL | | | status | int(11) | YES | | NULL | | | priority | int(11) | YES | | NULL | | | fk_site | int(11) | YES | MUL | NULL | | | resource_type | varchar(255) | YES | | NULL | | | resource_id | int(11) | YES | | NULL | | | fk_user | int(11) | YES | MUL | NULL | | +---------------+--------------+------+-----+---------+----------------+ Asset_links +-----------+---------+------+-----+---------+----------------+ | Field | Type | Null | Key | Default | Extra | +-----------+---------+------+-----+---------+----------------+ | id | int(11) | NO | PRI | NULL | auto_increment | | asset_id1 | int(11) | YES | | NULL | | | asset_id2 | int(11) | YES | | NULL | | +-----------+---------+------+-----+---------+----------------+ In the asset_links table there are the following rows: 1 - 3, 1 - 4, 2 - 10, 2 - 56 I am looking to write one query which will return all assets which satisfy any asset search criteria and within the same query return all of the linked asset data for linked assets for that asset. e.g. The query returning assets 1 and 2 would return : Asset 1 attributes - Asset 3 attributes - Asset 4 attributes Asset 2 attributes - Asset 10 attributes - Asset 56 attributes What is the best way to write the query?

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• How can I make Access think there is a primary key

  - by user3692757

  I have a table and I'm trying to join it with another table, but it doesn't have a distinctive primary key. The two tables do share similarities, “Acct” and “Location”. If I could concatenate “Acct&Location” it would become a primary key, but Access won’t let me make a primary key from a calculation. I provided a small sample below. Each hospital has an “Acct”, but the “Acct” will show up once for each “Location”. How can I make join these in a relationship? I connected the two in a relationships and tried to “Enforce Referential Integrity”, but it indicated “No unique index found for the referenced field of the primary key”. Also, if I run a “Find UnMatched Query” it doesn’t find anything. I think its because I can’t make it realize that in combination “Acct” and “Location” can be perceived as primary keys when used in conjunction of each other. Acct 1 2 3 1 2 3 1 2 3| Location ABI ABI ABI NHO NHO NHO NTX NTX NTX I tried to load an image to illustrate it better, but I haven't made enough post.

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• Entity Framework not populating context

  - by stimms

  I'm just starting out with some entity framework exploration, I figured it was time to see what everybody was complaining about. I am running into an issue where the entities don't seem to be returning any of the object context. I generated the model from a database with three tables which link to one another. Courses Instructors CanTeach Relationships are as you would expect: a course can relate to multiple CanTeach entities and an instructor can also relate to multiple CanTeach entities. I also added an OData service to my project which also makes use of the same model. So I can run queries like from a in CanTeach where a.Instructor.FirstName == "Barry" select new { Name = a.Instructor.FirstName + " " + a.Instructor.LastName, Course = a.Course.Name} without issue against the OData endpoint using LINQPad. However when I do a simple query like public Instructor GetInstructorFromID(int ID) { return context.Instructors.Where(i => i.ID == ID).FirstOrDefault(); } The CanTeach list is empty. I know everything in EF is lazy loaded and it is possible that my context is out of scope by the time I look at the object context, however even trying to get the object context as soon as the query is run results in and empty object context. What am I doing wrong?

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• Does Microsoft Access use the PK fields for anything?

  - by chrismay

  Ok this is going to sound strange, but I have inherited an app that is an Access front end with a SQL Server backend. I am in the process of writing a new front end for it, but... we need to continue using the access front end for a while even after we deploy my new front end for reasons I won't go into. So both the existing Access app and my new app will need to be able to access and work with the data. The problem is the database design is a nightmare. For example some simple parent-child table relationships have like 4 and 5 part composite primary keys. I would REALLY like to remove these PKs and replace them with unique constraints or whatever, and add a new column to each of these tables called ID that is just an identity. If I change the PK and FKs on these tables to more managable fields, will the Access app have problems? What I mean is, does access use the meta data from the tables (PK and FK info) in such a way that it would break the app to change these?

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• How to get around LazyInitializationException in scheduled jobs?

  - by Shreerang

  I am working on a J2EE server application which is deployed on Tomcat. I use Spring source as MVC framework and Hibernate as ORM provider. My object model has lot of Lazy relationships (dependent objects are fetched on request). The high level design is like Service level methods call a few DAO methods to perform database operation. The service method is called either from the Flex UI or as a scheduled job. When it is called from Flex UI, the service method works fine i.e. it fetches some objects using DAO methods and even Lazy loading works. This is possible by the use of OpenSessionInViewFilter configured with the UI servlet. But when the same service method is called as scheduled Job, it gives LazyInitializationException. I can not configure OpenSessionInViewFilter because there is no servlet or UI request associated with that. I tried configuring Transaction around the scheduled job method so that service method starts a transaction and all the DAO methods participate in that same transaction, hoping that the transaction will remain active and hibernate session will be available. But it does not work. Please suggest if anyone has ever been able to get such a configuration working. If needed, I can post the Hibernate configuration and log messages. Thanks a lot for help! Shreerang

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• How should approach allowing users to create notes with revisions?

  - by Magicked

  I'm working on a Rails project where I want to allow users to create individual notes, which are really just text fields at this time. With each note, the user can edit what they have previously written, but the old version is kept in a revision table. I'm trying to figure out the best way to approach this. My initial thoughts are to have the following relationships: class User < ActiveRecord::Base has_many :notes end class Note < ActiveRecord::Base has_many :note_revisions belongs_to :user end class NoteRevision < ActiveRecord::Base belongs_to :note_revision end The Note model will only contain a timestamp of when the note was first created. The NoteRevision model will contain the text, as well as a timestamp for each revision. This way, every time a new revision is made, a new entry is created into the NoteRevision table which is tracked through the Note table. Hopefully this makes sense! First, does this look like a good way to do this? If so, I'm having trouble figuring out how the controller and view will present this information in one form. Are there any good tutorials or has someone seen anything similar that can point me in the right direction? Thanks in advance!

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• Recoverable error while running XSL

  - by Kate

  XSL: <?xml version="1.0" encoding="utf-8"?> <xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" xmlns:ve="http://schemas.openxmlformats.org/markup-compatibility/2006" xmlns:o="urn:schemas-microsoft-com:office:office" xmlns:r="http://schemas.openxmlformats.org/officeDocument/2006/relationships" xmlns:m="http://schemas.openxmlformats.org/officeDocument/2006/math" xmlns:v="urn:schemas-microsoft-com:vml" xmlns:wp="http://schemas.openxmlformats.org/drawingml/2006/wordprocessingDrawing" xmlns:w10="urn:schemas-microsoft-com:office:word" xmlns:w="http://schemas.openxmlformats.org/wordprocessingml/2006/main" xmlns:wne="http://schemas.microsoft.com/office/word/2006/wordml" exclude-result-prefixes="wp wne w10 w ve o r m v" version="2.0"> <xsl:output method="text"/> <xsl:param name="styleName"/> <xsl:template match="w:p"> <xsl:apply-templates/><xsl:text>&#10;</xsl:text> </xsl:template> <xsl:template match="w:r[not ((parent::w:hyperlink[@w:anchor[matches(.,concat('^(',$styleName,')')),'i']]))]"> <xsl:value-of select="replace(., '.', '&#xFF00;')"/> </xsl:template> </xsl:stylesheet> While processing the above XSL, I am getting the below error, Recoverable Error: Recoverable error on line 11 FORG0006: An error occurred matching pattern {w:r[not ((parent::w:hyperlink[@w:anchor[matches(.,concat('^(',$styleName,')')),'i']]))]}: Effective boolean value is not defined for a sequence of two or more items starting with a boolean Please Help. I am not able to figure out this.

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• How do I organize C# classes that inherit from one another, but also have properties that inherit from one another?

  - by Chris

  I have an application that has a concept of a Venue, a place where events happen. A Venue is owned by a Company and has many VenueParts. So, it looks like this: public abstract class Venue { public int Id { get; set; } public string Name { get; set; } public virtual Company Company { get; set; } public virtual ICollection<VenuePart> VenueParts { get; set; } } A Venue can be a GolfCourseVenue, which is a Venue that has a Slope and a specific kind of VenuePart called a HoleVenuePart: public class GolfCourseVenue { public string Slope { get; set; } public virtual ICollection<HoleVenuePart> Holes { get; set; } } In the future, there may also be other kinds of Venues that all inherit from Venue. They might add their own fields, and will always have VenueParts of their own specific type. My declarations above seem wrong, because now I have a GolfCourseVenue with two collections, when really it should just have the one. I can't override it, because the type is different, right? When I run reports, I would like to refer to the classes generically, where I just spit out Venues and VenueParts. But, when I render forms and such, I would like to be specific. I have a lot of relationships like this and am wondering what I am doing wrong. For example, I have an Order that has OrderItems, but also specific kinds of Orders that have specific kinds of OrderItems.

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• Black Magic in Grails Data Binding!?

  - by Tiago Alves

  As described in http://n4.nabble.com/Grails-Data-Binding-for-One-To-Many-Relationships-with-REST-tp1754571p1754571.html i'm trying to automatically bind my REST data. I understand now that for one-to-many associations the map that is required for the data binding must have a list of ids of the many side such as: [propName: propValue, manyAssoc: [1, 2]] However, I'm getting this exception Executing action [save] of controller [com.example.DomainName] caused exception: org.springframework.orm.hibernate3.HibernateSystemException: IllegalArgumentException occurred calling getter of com.example.DomainName.id; nested exception is org.hibernate.PropertyAccessException: IllegalArgumentException occurred calling getter of com.example.DomainName.id However, even weirder is the update action that is generated for the controller. There we have the databinding like this: domainObjectInstance.properties = params['domainObject'] But, and this is the really weird thing, params['domainObject'] is null! It is null because all the domainObject fields are passed directly in the params map itself. If I change the above line to domainObjectInstance.properties = null the domainObject is still updated! Why is this happening and more important, how can I bind my incoming XML automatically if it comes in this format (the problem is the one-to-many associations): <product> <name>Table</name> <brand id="1" /> <categories> <category id="1" /> <category id="2" /> </categories> </product>

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• JDO architecture: One to many relationship and cascading deleting

  - by user361897

  I’m new to object oriented database designs and I’m trying to understand how I should be structuring my classes in JDO for google app engine, particularly one to many relationships. Let’s say I’m building a structure for a department store where there are many departments, and each department has many products. So I’d want to have a class called Department, with a variable that is a list of a Product class. @PersistenceCapable public class Department { @PrimaryKey @Persistent(valueStrategy = IdGeneratorStrategy.IDENTITY) private String deptID; @Persistent private String departmentName; @Persistent private List<Product>; } @PersistenceCapable public class Product { @PrimaryKey @Persistent(valueStrategy = IdGeneratorStrategy.IDENTITY) private String productID; @Persistent private String productName; } But one Product can be in more than one Department (like a battery could be in electronics and household supplies). So the next question is, how do I not duplicate data in the OOD world and have only one copy of product data in numerous departments? And the next question is, let’s say I delete out a particular product, how do each of the departments know it was deleted?

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• How to understand other people's CSS architectures?

  - by John

  I am reasonably good with CSS. However, when working with someone else's CSS, it's difficult for me to see the "bigger picture" in their architecture (but i have no problem when working with a CSS sheet I wrote myself). For example, I have no problems using Firebug to isolate and fix cross browser compatibility issues, or fixing a floating issue, or changing the height on a particular element. But if I'm asked to do something drastic such as, "I want the right sidebars of pages A, B, C and D to have a red border. I want the right side bars of pages E, F and G to have a blue border if and only if the user mouses over", then it takes me time a long time to map out all the CSS inheritance rules to see the "bigger picture". For some reason, I don't encounter the same difficulty with backend code. After a quick debriefing of how a feature works, and a quick inspection of the controller and model code, I will feel comfortable with the architecture. I will think, "it's reasonable to assume that there will be an Employee class that inherits from the Person Class that's used by a Department controller". If I discover inconvenient details that aren't consistent with overall architectural style, I am confident that I can hammer things back in place. With someone else's CSS work, it's much harder for me to see the "relationships" between different classes, and when and how the classes are used. When there are many inheritance rules, I feel overwhelmed. I'm having trouble articulating my question and issues... All I want to know is, why is it so much harder for me to see the bigger picture in someone else's CSS architecture than compared to someone else's business logic layer? **Does it have any thing to do with CSS being a relatively new technology, and there aren't many popular design patterns?

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• Entity Filter child without include

  - by Lic

  i'm a C# developer and i have a trouble with Entity Framework 5. I have mapped my database with Entity using the default code generation strategy. In particolar there are three classes: menus, submenus and submenuitems. The relationships about three classes are: one menu - to many submenus one submenu - to many submenuitems. All classes have a boolean attribute called "Active". Now, i want to filter all the Menus with the SubMenus active, and the SubMenus with the SubMenuItems active. To get this i've tried this: var tmp = _model.Menus.Where(m => m.Active) .Select => new { Menu = x, SubMenu = x.SubMenus.Where(sb => sb.Active) .Select(y => new { SubMenu = y, SubMenuItem = y.SubMenuItems.Where(sbi => sbi.Active) }) }) .Select(x => x.Menu).ToList(); But didn't work. Someone can help me? Thank you for your help!

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• Obfuscating ids in Rails app

  - by fphilipe

  I'm trying to obfuscate all the ids that leave the server, i.e., ids appearing in URLs and in the HTML output. I've written a simple Base62 lib that has the methods encode and decode. Defining—or better—overwriting the id method of an ActiveRecord to return the encoded version of the id and adjusting the controller to load the resource with the decoded params[:id] gives me the desired result. The ids now are base62 encoded in the urls and the response displays the correct resource. Now I started to notice that subresources defined through has_many relationships aren't loading. e.g. I have a record called User that has_many Posts. Now User.find(1).posts is empty although there are posts with user_id = 1. My explanation is that ActiveRecord must be comparing the user_id of Post with the method id of User—which I've overwritten—instead of comparing with self[:id]. So basically this renders my approach useless. What I would like to have is something like defining obfuscates_id in the model and that the rest would be taken care of, i.e., doing all the encoding/decoding at the appropriate locations and preventing ids to be returned by the server. Is there any gem available or does somebody have a hint how to accomplish this? I bet I'm not the first trying this.

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• REST Rails 2 nested routes without resource names?

  - by mrbrdo

  I'm using Rails 2. I have resources nested like this: - university_categories - universities - studies - professors - comments I wish to use RESTful routes, but I don't want all that clutter in my URL. For example instead of: /universities/:university_id/studies/:study_id/professors/:professor_id I want: /professors/:university_id/:study_id/:professor_id (I don't map professors seperately so there shouldn't be a confusion between this and /professors/:professor_id since that route shouldn't exist). Again, I want to use RESTful resources/routes... Also note, I am using slugs instead of IDs. Slugs for studies are NOT unique, while other are. Also, there are no many-to-many relationships (so if I know the slug of a professor, which is unique, I also know which study and university and category it belongs to, however I still wish this information to be in the URI if possible for SEO, and also it is necessary when adding a new professor). I do however want to use shallow nesting for "administrator" URIs like edit, destroy (note the problem here with Study since it's slug is not unique, though)... I would also like some tips on how to use the url helpers so that I don't have too much to fix if I change the routes in the future... Thank you.

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• Are reads and (transactional) writes faster for entities of the same group than otherwise?

  - by indiehacker

  What advantage is there to designing child-parent relationships, which allow us to do writes in transactions, when there is never a real concern for consistency and contention and those sort of more complex issues? Does it make writes and reads faster? Consider my situation where there are many .png images that are referenced to one mosaic layer, and these .png images are written just once by a single user. The user can design many mosaic layers and her mosaic layers and referenced image entities are never changed/updated, they are just deleted some time in the future. Other users can come to the web project site and interactively view the mosaic layer as different layouts/configurations of the images as they play (query) with different criteria. So reads should be very fast. So there is no real worry of contention, or users conflicting with one another with writing new image entities. And because of that I am assuming there is no "requirement" for the .png image entities to be grouped by their same mosaic layer in child-parent relationship. However, perhaps, since the documentation says they are stored close to one another, if the many image entities were grouped as children to a single mosaic layer parent than this has the advantage that the writing (in transaction) and reading will happen much faster?

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• List all foreign key constraints that refer to a particular column in a specific table

  - by Sid

  I would like to see a list of all the tables and columns that refer (either directly or indirectly) a specific column in the 'main' table via a foreign key constraint that has the ON DELETE=CASCADE setting missing. The tricky part is that there would be an indirect relationships buried across up to 5 levels deep. (example: ... great-grandchild- FK3 = grandchild = FK2 = child = FK1 = main table). We need to dig up the leaf tables-columns, not just the very 1st level. The 'good' part about this is that execution speed isn't of concern, it'll be run on a backup copy of the production db to fix any relational issues for the future. I did SELECT * FROM sys.foreign_keys but that gives me the name of the constraint - not the names of the child-parent tables and the columns in the relationship (the juicy bits). Plus the previous designer used short, non-descriptive/random names for the FK constraints, unlike our practice below The way we're adding constraints into SQL Server: ALTER TABLE [dbo].[UserEmailPrefs] WITH CHECK ADD CONSTRAINT [FK_UserEmailPrefs_UserMasterTable_UserId] FOREIGN KEY([UserId]) REFERENCES [dbo].[UserMasterTable] ([UserId]) ON DELETE CASCADE GO ALTER TABLE [dbo].[UserEmailPrefs] CHECK CONSTRAINT [FK_UserEmailPrefs_UserMasterTable_UserId] GO The comments in this SO question inpire this question.

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• Mysql - wondering about scaling a twitter-like application ?

  - by user246114

  Hi, I'm developing an app that is vaguely similar to twitter, in that it allows users to follow one another. I wanted to do this using google app engine, for its scalability promises, but it's proving kind of difficult to get running for a few different reasons. I'd basically like to have a _users table, and a _followers table. Users go into the users table, follower relationships go into _followers. The problem is that each row in the users table will probably have like 100 corresponding records in the _followers table as users start following one another. So the number of rows is going to explode quickly. Using app engine, the volume [shouldn't] be a problem. If I go with mysql, and I do actually start to get some traction, how do I scale this up? Am I going to just end up moving to a distributed database in the end anyway? Should I fight it out with google app engine? I read that Twitter was using mysql, and they've run into this problem, and are now switching to cassandra. Thanks

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• how are association, aggregation and composition written?

  - by ajsie

  i have read some posts about the differences between these 3 relationships and i think i get the point. i just wonder, are all these written the same when coding? question 1: all 3 are just a value of the object type in a instance variable? class A { public $b = '' public function __construct($object) { $this->b = $object // <-- could be a association, aggregation or a composition relation? } } question 2: does it have to be an instance variable or can it be a static one? class A { public static $b = '' // <-- nothing changed? public function __construct($object) { $this->b = $object } } question 3: is there a difference in where the object is created? i tend to think that composition object is created inside the object: class A { public $b = '' public function __construct() { $this->b = new Object // is created inside the object } } and aggregation/association is passed through a constructor or another method: class A { public $b = '' public function __construct($object) { // passed through a method $this->b = $object } } question 4: why/when is this important to know. do i have to comment an object inside another what relation its about or do you do it in an UML diagram? could someone shed a light on these questions. thanks!

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• Core Data Errors vs Exceptions Part 3

  - by John Gallagher

  My question is similar to this one. Background I'm creating a large number of objects in a core data store using NSOperations to speed things up. I've followed all the Core Data multithreading rules - I've got a single persistent store coordinator and a managed object context per thread that on save is merging back to the main managed object context. The Problem When the number of threads running at once is more than 1, I get the exception logged on save of my core data store: NSExceptionHandler has recorded the following exception: NSInternalInconsistencyException -- optimistic locking failure What I've Tried My code that creates new entities is quite complex - it makes entities that have relationships with other entities that could be being created in a separate thread. If I replace my object creation routine with some very simple code just making non-related entries, everything works perfectly. Initially, as well as the exceptions, I was getting a save error saying core data couldn't save due to the merge failing. I read the docs and realised I needed a merge policy on the Managed Object Context I was saving to. I set this up and as this question states, the save error goes away, but the exception remains. My Question Do I need to worry about these exceptions? If I do need to get rid of the exceptions, any ideas on how I do it?

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• CakePHP 2.0: how to access properties of the parent object?

  - by PaulJ

  I just started learning CakePHP 2.0 a few days ago, and there's one thing that is leaving me stumped: say I have an User model and a Posts model: class User extends AppModel { public $name = "User"; public $hasMany=array( 'Post' => array( 'className' => 'Post', 'foreignKey' => 'author_id' ) ); } class Post extends AppModel { public $name = 'Post'; public $belongsTo = array( 'className' = 'User', 'foreignKey' = 'author_id', ); } (Where "author_id" is the foreign key in the posts table that references the Users table's primary key). And now, in the PostsController, I want to access the properties of the user that owns the current post (to show his display name, for example). What would be the proper syntax? I tried: $this->Post->User->find('first', array('conditions' => array('User.id' => "$usuario"))) But it didn't work (I guess it's because the User is the parent of the Post object, not its child). Or should CakePHP load everything automatically, once you've declared the $hasMany and $belongsTo relationships?

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• HABTM selection seemingly ignores joinTable

  - by TheCapn

  I'm attempting to do a HABTM relationship between a Users table and Groups table. The problem is, that I when I issue this call: $this->User->Group->find('list'); The query that is issued is: SELECT [Group].[id] AS [Group__id], [Group].[name] AS [Group__name] FROM [groups] AS [Group] WHERE 1 = 1 I can only assume at this point that I have defined my relationship wrong as I would expect behavior to use the groups_users table that is defined on the database as per convention. My relationships: class User extends AppModel { var $name = 'User'; //...snip... var $hasAndBelongsToMany = array( 'Group' => array( 'className' => 'Group', 'foreignKey' => 'user_id', 'associationForeignKey' => 'group_id', 'joinTable' => 'groups_users', 'unique' => true, ) ); //...snip... } class Group extends AppModel { var $name = 'Group'; var $hasAndBelongsToMany = array ( 'User' => array( 'className' => 'User', 'foreignKey' => 'group_id', 'associationForeignKey' => 'user_id', 'joinTable' => 'groups_users', 'unique' => true, )); } Is my understanding of HABTM wrong? How would I implement this Many to Many relationship where I can use CakePHP to query the groups_users table such that a list of groups the currently authenticated user is associated with is returned?

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• Social Networking & Network Affiliations

  - by Code Sherpa

  Hi. I am in the process of planning a database for a social networking project and stumbled upon this url which is a (crude) reverse engineered guess at facebook's schema: http://www.flickr.com/photos/ikhnaton2/533233247/ What is of interest to me is the notion of "Affiliations" and I am trying to fully understand how they work, technically speaking. Where I am somewhat confused is the NetworkID column in the FacebookGroups", "FacebookEvent", and "Affiliations" tables (NID in Affiliations). How are these network affiliations interconnected? In my own project, I have a simple profile table: CREATE TABLE [dbo].[Profiles]( [profileid] [int] IDENTITY(1,1) NOT NULL, [userid] [uniqueidentifier] NOT NULL, [username] [varchar](255) COLLATE Latin1_General_CI_AI NOT NULL, [applicationname] [varchar](255) COLLATE Latin1_General_CI_AI NOT NULL, [isanonymous] [bit] NULL, [lastactivity] [datetime] NULL, [lastupdated] [datetime] NULL, CONSTRAINT [PK__Profiles__1DB06A4F] PRIMARY KEY CLUSTERED ( [profileid] ASC )WITH (IGNORE_DUP_KEY = OFF) ON [PRIMARY], CONSTRAINT [PKProfiles] UNIQUE NONCLUSTERED ( [username] ASC, [applicationname] ASC )WITH (IGNORE_DUP_KEY = OFF) ON [PRIMARY] ) ON [PRIMARY] One profile can have many affiliations. And one affiliation can have many profiles. And I would like to design it in such a way that relationships between affiliations tells me something about the associated profiles. In fact, based on the affiliations that users select, I would like to know how to infer as many things as possible about that person. My question is, how should I be designing my network affiliation tables and how do they operate per my above requirements? A rough SQL schema would be appreciated in your response. Thanks in advance...

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• data ownership and performance

  - by Ami

  We're designing a new application and we ran into some architectural question when thinking about data ownership. we broke down the system into components, for example Customer and Order. each of this component/module is responsible for a specific business domain, i.e. Customer deals with CRUD of customers and business process centered around customers (Register a n new customer, block customer account, etc.). each module is the owner of a set of database tables, and only that module may access them. if another module needs data that is owned by another module, it retrieves it by requesting it from that module. so far so good, the question is how to deal with scenarios such as a report that needs to show all the customers and for each customer all his orders? in such a case we need to get all the customers from the Customer module, iterate over them and for each one get all the data from the Order module. performance won't be good...obviously it would be much better to have a stored proc join customers table and orders table, but that would also mean direct access to the data that is owned by another module, creating coupling and dependencies that we wish to avoid. this is a simplified example, we're dealing with an enterprise application with a lot of business entities and relationships, and my goal is to keep it clean and as loosely coupled as possible. I foresee in the future many changes to the data scheme, and possibly splitting the system into several completely separate systems. I wish to have a design that would allow this to be done in a relatively easy way. Thanks!

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