I have a join table where the original table is a numeric type and the join table key column is a string type. Legacy decision that I am trying to avoid having to change to minimize the risk to the scope of work. HasManyToMany<Attachment>(x => x.Attachments) .Table("ObjectAttachments") .ParentKeyColumn("ObjectId") .ChildKeyColumn...
I have the folowing model: class Step(models.Model): order = models.IntegerField() latitude = models.FloatField() longitude = models.FloatField() date = DateField(blank=True, null=True) class Journey(models.Model): boat = models.ForeignKey(Boat) route = models.ManyToManyField(Step) departure = models.Fore...
What is the best way of handling many-to-many relations in a RDBMS database like mySQL? Have tried using a pivot table to keep track of the relationships, but it leads to either one of the following: Normalization gets left behind Columns that is empty or null What approach have you taken in order to support many-to-many relationsh...
Hi there! I'm using two entities A and B with to-many-to-many relationship. Lets say I got an entity A with attribute aAttrib and a to-many relationship aRelat to another entity B with attribute bAttrib and a to-many relationship bRelat with entity A. Now I am building an interface with two tables one for entity A and another for entit...
I have the following class public class ElementBean { private String link; private Set<ElementBean> connections; } I need to create a map table where elements are mapped to each other in a many-to-many symmetrical relationship. @ManyToMany(targetEntity=ElementBean.class) @JoinTable( name="element_elements", joinColumns=@Jo...
I have two models: class Actor(models.Model): name = models.CharField(max_length=30, unique = True) event = models.ManyToManyField(Event, blank=True, null=True) class Event(models.Model): name = models.CharField(max_length=30, unique = True) long_description = models.TextField(blank=True, null=True) I want to cr...
I am using a ModelForm to create a form, and I have gotten the initial values set for every field in the form except for the one that is a ManyToMany field. I understand that I need to give it a list, but I can't get it to work. My code in my view right now is: userProfile = request.user.get_profile() employer = userPr...
As I am learning more about rails, and breaking my design thinking from ASP.Net days, I was considering a scenario this morning but did not know if it was possible to do. Practitioners have many Treatments through services - and vice versa In my control Panel I have an area for Practitioners to edit their details (names, contact info e...
I'm having some problems getting a many-to-many relationship working in grails. Is there anything obviously wrong with the following: class Person { static hasMany = [friends: Person] static mappedBy = [friends: 'friends'] String name List friends = [] String toString() { return this.name } } class Bo...
I haven't implemented a search feature before and feel a bit stuck. I have a Sunspot search feature which finds results based on keywords - this works great - but I now want to implement the multi select facet feature, but I can't even seem to figure out how to set-up a basic facet search. I have a many to many relationship (in rails no...
My questions seems like a common problem that when I have seen any questions on it is never really asked right or not answered. So Im going to try to get the question right, and maybe someone knows how to resolve the issue, or correct my understanding. The problem: When you have a many-to-many relation ship (related_name not through) a...
When I include a ModelToModelField to one of my models the following error is thrown. Traceback (most recent call last): File "manage.py", line 11, in <module> execute_manager(settings) File "/Library/Python/2.6/site-packages/django/core/management/__init__.py", line 362, in execute_manager utility.execute() File "/Library/Pytho...
I have two models: class Actor(models.Model): name = models.CharField(max_length=30, unique = True) event = models.ManyToManyField(Event, blank=True, null=True) class Event(models.Model): name = models.CharField(max_length=30, unique = True) long_description = models.TextField(blank=True, null=True) In a previou...
Hi, I have to classes, ClassA and ClassB and a "many to many" AssociationClass. I want to use a structure to hold the associations between A and B such as I can know, for each instance of A or B, which are their counterparts. I thought of using a Hashmap, with pair keys: Hasmap<Pair<ClassA, ClassB>, AssociationClass> associations; ...
If I were to have two different QuerySets in Django, both representing a ManyToMany relation with the same model, how would I find the intersections? ...
Basically my setup is this. I have a many-to-many relationship in Core Data where a student entity can have multiple courses, and a course entity can have multiple students. My problem is in trying to figure out how to bind this relationship to the UI in Interface Builder. I want to be able to add courses to a course array controller, t...
Hi all! I have many-to-many relations with the following tables. post tag post_tag I created three classes with Doctrine, so I have the following classes as well. BasePost BaseTag BasePostTag in the setUp() method, I defined relations. I like to delete tag record when I delete post record. So I simply put cascade as descirbed on Doc...
Hi All, I am trying to delete records in many to many using Doctrine. I used code on http://www.doctrine-project.org/documentation/manual/1_2/ru/working-with-models#many-to-many-relations:deleting-a-link when I do the first method, it just deletes UserGroup record ONLY. How do I delete User, Group, and UserGroup records at once? The se...
If I had, for example, a Many-to-Many mapping table called "RolesToUsers" between a Users and an Roles table, here is how I do it: // DataContext is db, usr is a User entity // newUserRolesMappings is a collection with the desired new mappings, probably // derived by looking at selections in a checkbox list of Roles on a User Edit pa...
I've been reading up on foreign keys and joins recently, and have been pleasantly surprised that many of the basic concepts are things I'm already putting into practice. For example, with one project I'm currently working on, I'm organizing word lists, and have a table for the sets, like so: `words` Table `word_id` `headword` ...