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• Creating a view linking three different node types with two node references

  - by mikesir87

  I have the following content types: Camp - the top level type Registration Information - contains node reference to Camp called Camp Medical Release Form - contains node reference to registration information called Camper I would like to create a View that takes the nid for the Camp, and pulls out all the fields for the Registration Info and Medical Release Form. I'm having trouble figuring out how to set up the various arguments/relationships. I haven't done something that's referenced more than two types. I know it would be smart/best to just combine the Registration Info and Medical Release Form, since it's a 1:1 mapping, but we can't. So... any help would be appreciated!

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• Foreign key on table A --> B, AND foreign key on table B --> A. How is this done?

  - by unclaimedbaggage

  Hi, I have two tables - 'business' and 'business_contacts'. The business_contact table has a many-to-one relationship with the business table. Furthermore, each business has a 'primary contact' field - which I'd assume is a one-to-many relationship with the business_contacts table. The problem, of course, is that this creates a catch-22 for data insertion. Since neither field can be null, I can't insert a business_contact until I have a corresponding business, but I can't insert a business until I have a corresponding business_contact. If anyone could help me get my head around how mutual one-to-many relationships are supposed to be dealt with I'd be most appreciative. (Project being done in MySQL if it makes any difference)

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• Rails architecture questions

  - by justinbach

  I'm building a Rails site that, among other things, allows users to build their own recipe repository. Recipes are entered either manually or via a link to another site (think epicurious, cooks.com, etc). I'm writing scripts that will scrape a recipe from these sites given a link from a user, and so far (legal issues notwithstanding) that part isn't giving me any trouble. However, I'm not sure where to put the code that I'm writing for these scraper scripts. My first thought was to put it in the recipes model, but it seems a bit too involved to go there; would a library or a helper be more appropriate? Also, as I mentioned, I'm building several different scrapers for different food websites. It seems to me that the elegant way to do this would be to define an interface (or abstract base class) that determines a set of methods for constructing a recipe object given a link, but I'm not sure what the best approach would be here, either. How might I build out these OO relationships, and where should the code go?

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• Design ideas for a versioned db schema with related tables also versioned

  - by vfilby

  Here is the drill, I want to version a database. I have done this before using multiple rows where the table primary key becomes a combination of the row id and either a datestamp or a version #. Now I want to version a table that depends on many other small tables. Versioning each table will be a giant PITA, so I am looking for good options to verion a schema where the data to be versioned spreads over multiple tables. All related tables are properly keyed with foreign key relationships. The database is currently on Sql Server 2005.

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• NSFetchedResultsChangeInsert reported when only updates are taking place

  - by niblha

  I have a class that acts as a NSFetchedResultsControllerDelegate which is receiving messages to -(void)controller:didChangeObject:atIndexPath:forChangeType:newIndexPath: with change type NSFetchedResultsChangeInsert, but the actual object which is the subject has with certainty not been newly inserted, only updated. So I would expect to get a change message with type NSFetchedResultsChangeUpdate, should I not? If i check the value of isInserted on the object, it yields false (as expected from the logic in my program). So my question is, why is this reported as an insert when it is only a change/update? They only thing I can think of is that part of the changes that are taking place is that objects of another entity type are inserted with relationships to objects of the entity type that the NSFetchedResultsController is set up to fetch.

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• Rails 2.3.5: How does one add an error when it doesn't make sense to put it in a validation?

  - by randombits

  I recently was trying to add errors.add_to_base code in the middle of some model logic and was wondering why it wasn't showing up in my view that was iterating over all errors. I then ran across this e-mail which explains why: http://groups.google.com/group/rubyonrails-talk/browse_thread/thread/e045ec1dead1ff06?pli=1 The question is then, how does one add errors with add_to_base if it doesn't make sense to put them into a validate method? I have some complex logic. The model needs to talk to a has_many relationship which has its own relationships that go through a myriad of conditionals to figure out if a request makes sense. It's nothing that can be tied to a validate method easily. How does one add errors then accordingly?

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• T-SQL Getting duplicate rows returned

  - by cBlaine

  The following code section is returning multiple columns for a few records. SELECT a.ClientID,ltrim(rtrim(c.FirstName)) + ' ' + case when c.MiddleName <> '' then ltrim(rtrim(c.MiddleName)) + '. ' else '' end + ltrim(rtrim(c.LastName)) as ClientName, a.MISCode, b.Address, b.City, dbo.ClientGetEnrolledPrograms(CONVERT(int,a.ClientID)) as Abbreviation FROM ClientDetail a JOIN Address b on(a.PersonID = b.PersonID) JOIN Person c on(a.PersonID = c.PersonID) LEFT JOIN ProgramEnrollments d on(d.ClientID = a.ClientID and d.Status = 'Enrolled' and d.HistoricalPKID is null) LEFT JOIN Program e on(d.ProgramID = e.ProgramID and e.HistoricalPKID is null) WHERE a.MichiganWorksData=1 I've isolated the issue to the ProgramEnrollments table. This table holds one-to-many relationships where each ClientID can be enrolled in many programs. So for each program a client is enrolled in, there is a record in the table. The final result set is therefore returning a row for each row in the ProgramEnrollments table based on these joins. I presume my join is the issue but I don't see the problem. Thoughts/Suggestions? Thanks, Chuck

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• Many-to-many relationship on same table with association object

  - by Nicholas Knight

  Related (for the no-association-object use case): http://stackoverflow.com/questions/1889251/sqlalchemy-many-to-many-relationship-on-a-single-table Building a many-to-many relationship is easy. Building a many-to-many relationship on the same table is almost as easy, as documented in the above question. Building a many-to-many relationship with an association object is also easy. What I can't seem to find is the right way to combine association objects and many-to-many relationships with the left and right sides being the same table. So, starting from the simple, naïve, and clearly wrong version that I've spent forever trying to massage into the right version: t_groups = Table('groups', metadata, Column('id', Integer, primary_key=True), ) t_group_groups = Table('group_groups', metadata, Column('parent_group_id', Integer, ForeignKey('groups.id'), primary_key=True, nullable=False), Column('child_group_id', Integer, ForeignKey('groups.id'), primary_key=True, nullable=False), Column('expires', DateTime), ) mapper(Group_To_Group, t_group_groups, properties={ 'parent_group':relationship(Group), 'child_group':relationship(Group), }) What's the right way to map this relationship?

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• How to create relationship mapping via Entity framework

  - by James

  I have following domain model: User { int Id; } City { int Id; } UserCity { int UserId, int CityId, dateTime StartDate } In the function where I have to attach a user to a city, the following code is working for me: UserCity uc = new UserCity(); //This is a db hit uc.User = MyEntityFrameworkDBContext.User.FirstOrDefault(u => u.ID == currentUserId); //this is a db hit uc.City = MyEntityFrameworkDBContext.City.FirstOrDefault(c => c.ID == currentCityId); uc.StartDate = userCityStartDate; //this is a db hit MyEntityFrameworkDBContext.SaveChanges(); Is there any way I can create relationships with just one single DB hit? The first two db hits are not required, actually.

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• What is an algorithm for minimizing some D distances between N items?

  - by Ross

  A classmate printed out a diagram of a database for class, the kind with lines representing relationships between tables. However, his lines crossed all over the place and it looked ugly. So I got to thinking about a way to move the tables to minimize the total line distance, and I couldn't think of a way to do it, other than just moving them all on top of each other. So basically: Given N items on some 2d coordinate space and some amount of connections between pairs of those items, how do you move the items so that the total distance between pairs is minimal, but that no distance is smaller than S? (so that the tables would not be too close together) Is there some algorithm for this? (I realize that smallest total distance won't necessarily make the layout less ugly; lines might still cross. But the table layout is just what got me thinking)

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• has_many relation doesn't seems right or logical, some thing like belongs_to_many looks right

  - by Vijendra

  My situation is like this. Company has many users and users may belongs to many companies. And current implementation is something like below. class Company has_many :employments has_many :users, :through = :employments end class Employment belongs_to :company belongs_to :user end class User has_many :employments has_many :companies, :through = :employments #This doesn't looks correct end User has many companies doesn't looks logically meaningful.It must be some thing like belongs_to_many companies. Do I need to use has_and_belongs_to_many? But that also will gives the same meaning. Can some one please suggest the right way for representing these relationships?

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• Javascript Library - Family Tree Flowchart

  - by MrMime

  Im looking for a simple Javascript Library (svg?) that allow me to draw a family tree relationships. I have searched a lot on google found a lot of interesting libraries like Raphaël and its extention Dracula. Google has its own library to make flowcharts too. Unfortunally, every library make a relation between nodes with a sigle line. If A and B has a relation to C, I will obtain 2 line: one from A to C and one from B to C. What I need is a line from A to B (we call it AB) and a line from AB to C to represent the Marriage of A and B. example-image Thanks.

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• Show a django relationship in a template

  - by kevin_82

  I have a django model as follows: class Person(models.Model): name = models.CharField(max_length=255) class Relationship(models.Model): parent = models.ForeignKey(Person) child = models.ForeignKey(Person) description = models.TextField(blank=True) In my view, I pass a certain person, and the relationships in which he/she is parent: person = Person.objects.filter(name ='some name') descendant_relationships = Relationship.objects.filter(parent = person) An I want to show this person's descendants in a list in a template: <ul> {% for item in descendant_relationships%} <li> {{item.child.name}} - {{item.description}} </li> {% endfor %} </ul> But this template code will not show the children of children (i.e. grandchildren, great-grandchildren etc.). How can I get these lower level descendants to show up? I imagine recursion is necessary somewhere, but where?

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• Hibernate - why use many-to-one to represent a one-to-one?

  - by aberrant80

  I've seen people use many-to-one mappings to represent one-to-one relationships. I've also read this in a book by Gavin King and on articles. For example, if a customer can have exactly one shipping address, and a shipping address can belong to only one customer, the mapping is given as: <class name="Customer" table="CUSTOMERS"> ... <many-to-one name="shippingAddress" class="Address" column="SHIPPING_ADDRESS_ID" cascade="save-update" unique="true"/> ... </class> The book reasons as (quoting it): "You don't care what's on the target side of the association, so you can treat it like a to-one association without the many part." My question is, why use many-to-one and not one-to-one? What is it about a one-to-one that makes it a less desirable option to many-to-one? Thanks.

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• transform file/directory structure into 'tree' in javascript

  - by dave

  I have an array of objects that looks like this: [{ name: 'test', size: 0, type: 'directory', path: '/storage/test' }, { name: 'asdf', size: 170, type: 'directory', path: '/storage/test/asdf' }, { name: '2.txt', size: 0, type: 'file', path: '/storage/test/asdf/2.txt' }] There could be any number of arbitrary path's, this is the result of iterating through files and folders within a directory. What I'm trying to do is determine the 'root' node of these. Ultimately, this will be stored in mongodb and use materialized path to determine it's relationships. In this example, /storage/test is a root with no parent. /storage/test/asdf has the parent of /storage/test which is the parent to /storage/test/asdf/2.txt. My question is, how would you go about iterating through this array, to determine the parent's and associated children? Any help in the right direction would be great! Thank you

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• How to organise a many to many relationship in MongoDB

  - by Gareth Elms

  I have two tables/collections; Users and Groups. A user can be a member of any number of groups and a user can also be an owner of any number of groups. In a relational database I'd probably have a third table called UserGroups with a UserID column, a GroupID column and an IsOwner column. I'm using MongoDB and I'm sure there is a different approach for this kind of relationship in a document database. Should I embed the list of groups and groups-as-owner inside the Users table as two arrays of ObjectIDs? Should I also store the list of members and owners in the Groups table as two arrays, effectively mirroring the relationship causing a duplication of relationship information? Or is a bridging UserGroups table a legitimate concept in document databases for many to many relationships? Thanks

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• Pre loaded database on iPhone?

  - by Julian

  Hi, I have recently developed an app using core data as the storage db. The app allowed the user to read and write to the db. I am now developing a new app which the user doesnt need to write anything to the db, instead the app just needs to read the data. The data has relationships etc so cannot just use a plist or something similar. My question is should I use core data for such a requirement and if so how would i go about entering the data and then releasing the app. Would I have to code the data entry which would populate the db then remove all this code (as I dont want the database to repopulate every time the user opens the app)?? Is there a way to create a core data model using sql commands as with sqlite ie insert into..... etc? Any ideas/thoughts would be very helpful. Many thanks Jules

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• how do I integrate the aspnet_users table that comes with asp.net membership into my existing databa

  - by ooo

  i have a database that already has a users table COLUMNS: userID - int loginName - string First - string Last - string i just installed the asp.net membership table. Right now all of my tables are joined into my users table foreign keyed into the "userId" field How do i integrate asp.net_users table into my schema? here are the ideas i thought of: Add a membership_id field to my users table and on new inserts, include that new field in my users table. This seems like the cleanest way as i dont need to break any existing relationships. break all existing relationship and move all of the fields in my user table into the asp.net_users table. This seems like a pain but ultimately will lead to the most simple, normalized solution any thoughts?

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• How do you manage web navigation info in your application?

  - by Dave

  I’m building an application where different users will have different menu items available to them depending on what they’ve paid for. There will also be multiple levels to the menu hierarchy. What’s the best approach to this problem? I’m assuming I need a database table that represents the menu hierarchy, including the parent-child relationships of the nodes in the navigation as well as the sorting of the items. Then another table which I use to manage whether a user is authorized to access a particular item in that table. When I render the view, I’d reference the menus, and the access rights of the user to output the menu, and I’d also need a function to check that same authorization from each controller in case a user manually types in a URL of a controller they’re not supposed to have access to. Is this the right approach? Any suggestions for caching this to prevent the constant look-ups of this type of info? I’m open to any suggestions on how you may have approached this type of requirement.

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• Zend DB inserting relational data

  - by Wimbjorno

  I'm using the Zend Framework database relationships for a couple of weeks now. My first impression is pretty good, but I do have a question related to inserting related data into multiple tables. For a little test application I've related two tables with each other by using a fuse table. +---------------+ +---------------+ +---------------+ | Pages | | Fuse | | Prints | +---------------+ +---------------+ +---------------+ | pageid | | fuseid | | printid | | page_active | | fuse_page | | print_title | | page_author | | fuse_print | | print_content | | page_created | | fuse_locale | | ... | | ... | | ... | +---------------+ +---------------+ +---------------+ Above is an example of my DB architecture Now, my problem is how to insert related data to two separate tables and insert the two newly created ID's into the fuse table at the same time. If someone could could maybe explain or give me a topic related tutorial. I would appreciate it!

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• Assign TableView column binding to a specific core-data object in to-many related entity based on se

  - by snown27

  How would I assign a column of a TableView to be a specific entry in a Core Data entity that is linked to the NSArrayController via a to-many relationship? For example Entity: MovieEntity Attributes: title(NSString), releaseDate(NSDate) Relationship: posters<-->> PosterEntity Entity:PosterEntity Attributes: imageLocation(NSURL), default(BOOL) Relationships: movie<<--> MovieEntity So I have a three column table that I want to display the Poster, Title, and Release Date attributes in, but as one movie could potentially have several different style's of posters how do I get the poster column to only show the one that's marked default? Since the rest of the table is defined in Interface Builder I would prefer to keep it that way for the sake of keeping the code as clean as possible, but if this can only be done programmatically then I'm all ears. I just wanted to give preference in case there's more than one way to skin a cat, so to speak.

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• Missing something with Entity Framework for .NET 3.5?

  - by AC

  Is it not possible to have EF create the necessary entities when I have two related tables linked with a FK in .NET3.5SP1? I see where the checkbox to support this is disabled but it is available in .NET4. I've got a DB that has only tables with relationships in it. I need to build a Silverlight app (SL4) that allows management of the data within this app. I can't use .NET4 on the server... only .NET3.5SP1 so FK relationship bit in EF4 isn't available to me. Looking to avoid building as much of the plumbing to get back to the DB from the SL4 app as possible...

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• how do I integrate the aspnet_users table (asp.net membership) into my existing database

  - by ooo

  i have a database that already has a users table COLUMNS: userID - int loginName - string First - string Last - string i just installed the asp.net membership table. Right now all of my tables are joined into my users table foreign keyed into the "userId" field How do i integrate asp.net_users table into my schema? here are the ideas i thought of: Add a membership_id field to my users table and on new inserts, include that new field in my users table. This seems like the cleanest way as i dont need to break any existing relationships. break all existing relationship and move all of the fields in my user table into the asp.net_users table. This seems like a pain but ultimately will lead to the most simple, normalized solution any thoughts?

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• NSPredicate aggregate function [SIZE] gives 'unsupported function expression' error

  - by jinglesthula

  iOS 4: I have entities in Core Data (using SQLite, which is a requirement) of: Request Response (which has a property personId) Revision Relationships are: Request <-- Revision Request <-- Response Revision <-- Response (e.g. each request may have many responses; each request/response pair may have many revisions) I'm trying to do a predicate to get all Responses with a given personId that have zero Revisions. Using: (personId == %d) && (Request.Revision[SIZE] == 0) in my predicate string gives me a runtime exception "Unsupported function expression Request.Revision[SIZE]" The documentation seems pretty sparse on aggregate functions, only noting that they exist, but with no syntax or examples. Not sure if it's my syntax or if the SIZE function really isn't supported in iOS.

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• has_many relation doesn't seems right or logical in business perceptive, needed some thing like belo

  - by Vijendra

  My situation is like this. Company has many users and users may belongs to many companies. And current implementation is something like below. class Company has_many :employments has_many :users, :through = :employments end class Employment belongs_to :company belongs_to :user end class User has_many :employments has_many :companies, :through = :employments #This doesn't looks correct end It works, but "user has many companies" doesn't looks logically meaningful. It must be some thing like belongs_to_many companies. Do I need to use has_and_belongs_to_many? Can some one please suggest the right way for representing these relationships?

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