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  • can I make this select follower/following script more organized? (PHP/Mysql)

    - by ggfan
    In this script, it gets the followers of a user and the people the user is following. Is there a better relationship/database structure to get a user's followers and who they are following? All I have right now is 2 columns to determine their relationship. I feel this is "too simple"? (MYSQL) USER | FRIEND avian gary cend gary gary avian mike gary (PHP) $followers = array(); $followings = array(); $view = $_SESSION['user']; //view is the person logged in $query = "SELECT * FROM friends WHERE user='$view'"; $result = $db->query($query); while($row=$result->fetch_array()) { $follower=$row['friend']; $followers[] = $follower; } print_r($followers); echo "<br/>"; $query2 = "SELECT * FROM friends WHERE friend='$view'"; $result2 = $db->query($query2); while($row2=$result2->fetch_array()) { $following=$row2['user']; $followings[] = $following; } print_r($followings); echo "<br/>"; $mutual = array_intersect($followers, $followings); print_r($mutual); **DISPLAY** Your mutual friends avian Your followers avian You are following avian cen mike (I know avian is in all 3 displays, but I want to keep it that way)

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  • Rails: Multiple "has_many through" for the two same models?

    - by neezer
    Can't wrap my head around this... class User < ActiveRecord::Base has_many :fantasies, :through => :fantasizings has_many :fantasizings, :dependent => :destroy end class Fantasy < ActiveRecord::Base has_many :users, :through => :fantasizings has_many :fantasizings, :dependent => :destroy end class Fantasizing < ActiveRecord::Base belongs_to :user belongs_to :fantasy end ... which works fine for my primary relationship, in that a User can have many Fantasies, and that a Fantasy can belong to many Users. However, I need to add another relationship for liking (as in, a User "likes" a Fantasy rather than "has" it... think of Facebook and how you can "like" a wall-post, even though it doesn't "belong" to you... in fact, the Facebook example is almost exactly what I'm aiming for). I gathered that I should make another association, but I'm kinda confused as to how I might use it, or if this is even the right approach. I started by adding the following: class Fantasy < ActiveRecord::Base ... has_many :users, :through => :approvals has_many :approvals, :dependent => :destroy end class User < ActiveRecord::Base ... has_many :fantasies, :through => :approvals has_many :approvals, :dependent => :destroy end class Approval < ActiveRecord::Base belongs_to :user belongs_to :fantasy end ... but how do I create the association through Approval rather than through Fantasizing? If someone could set me straight on this, I'd be much obliged!

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  • LINQ-To-SQL and Mapping Table Deletions

    - by Jake
    I have a many-to-many relationship between two tables, let's say Friends and Foods. If a friend likes a food I stick a row into the FriendsFoods table, like this: ID Friend Food 1 'Tom' 'Pizza' FriendsFoods has a Primary Key 'ID', and two non-null foreign keys 'Friend' and 'Food' to the 'Friends' and 'Foods' tables, respectively. Now suppose I have a Friend tom .NET object corresponding to 'Tom', and Tom no longer likes pizza (what is wrong with him?) FriendsFoods ff = tblFriendsFoods.Where(x => x.Friend.Name == 'Tom' && x.Food.Name == 'Pizza').Single(); tom.FriendsFoods.Remove(ff); pizza.FriendsFoods.Remove(ff); If I try to SubmitChanges() on the DataContext, I get an exception because it attempts to insert a null into the Friend and Food columns in the FriendsFoods table. I'm sure I can put together some kind of convoluted logic to track changes to the FriendsFoods table, intercept SubmitChanges() calls, etc to try and get this to work the way I want, but is there a nice, clean way to remove a Many-To-Many relationship with LINQ-To-SQL?

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  • has_many :through formtastic multi-select field

    - by Tristan O'Neil
    I'm trying to set up a many to many relationship using the has_many :through method and then use a multi-select field to setup the relationships. I'm following this tutorial: http://asciicasts.com/episodes/185-formtastic-part-2 However for some reason the form displays a strange hex number and it changes each page refresh, I'm not exactly sure what I'm doing wrong. Below is my model/view code. company.rb has_many :classifications has_many :sics, :through => :classifications sic.rb has_many :classifications has_many :companies, :through => :classifications classification.rb belongs_to :company belongs_to :sic _form.html.erb <% semantic_form_for @company do |f| %> <% f.inputs do %> <%= f.input :company %> <%= f.input :sics %> <% end %> <%= f.buttons %> <% end %> Also here is the the form looks like it's showing the correct number of entries for the field but it is clearly not showing the correct name for the relationship.

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  • RESTfully Nesting Resource Routes with Single Identifiers

    - by Craig Walker
    In my Rails app I have a fairly standard has_many relationship between two entities. A Foo has zero or more Bars; a Bar belongs to exactly one Foo. Both Foo and Bar are identified by a single integer ID value. These values are unique across all of their respective instances. Bar is existence dependent on Foo: it makes no sense to have a Bar without a Foo. There's two ways to RESTfully references instances of these classes. Given a Foo.id of "100" and a Bar.id of "200": Reference each Foo and Bar through their own "top-level" URL routes, like so: /foo/100 /bar/200 Reference Bar as a nested resource through its instance of Foo: /foo/100 /foo/100/bar/200 I like the nested routes in #2 as it more closely represents the actual dependency relationship between the entities. However, it does seem to involve a lot of extra work for very little gain. Assuming that I know about a particular Bar, I don't need to be told about a particular Foo; I can derive that from the Bar itself. In fact, I probably should be validating the routed Foo everywhere I go (so that you couldn't do /foo/150/bar/200, assuming Bar 200 is not assigned to Foo 150). Ultimately, I don't see what this brings me. So, are there any other arguments for or against these two routing schemes?

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  • Is this a tableView issue or a CoreData Issue

    - by monotreme
    I have a CoreData-driven navigation app and I'm trying to figure out why It's crashing. I've got a hierarchy which is 3 view Controllers deep, all related by coredata relatioships, like this. TableViewA =relationship= TableViewB =relationship= TableViewC I'm honestly a novice at core data and I think my problem lies in the fetched results controller. I have one in TableViewA and another in TableViewB, and no matter how deep I go, the console always cites TableViewB's fetched results controller methods after a crash. Is this the problem? What's happening specifically is if I launch my app and drill down into the hierarchy of one record, let's call it Record1, I can delete sub records to my hearts content. Gone! no problem! But the second I go back to TableViewA and drill down into a different record, let's call that one Record2, and try to delete it's subrecords my app crashes, with the console citing this code from TableViewB as the problem. - (void)controllerWillChangeContent:(NSFetchedResultsController *)controller { // The fetch controller is about to start sending change notifications, so prepare the table view for updates. [self.tableView beginUpdates]; } When I go into the debugger, the specific method it always has a problem with is: if (![x.managedObjectContext save:&error]) { NSLog(@"Unresolved error %@, %@", error, [error userInfo]); abort(); } Just a confirmation of my idiocy with CoreData is all I'm looking for I think. Oh and how many ManagedObjectContexts should I have in an app of this type. I've been told I should have separate ones for adding content, which then should re-integrate into the main one. Is this true? Thanks!

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  • Hibernate mapping - "Could not determine type"

    - by Pool
    I currently have the following objects persisting successfully: Person first name, etc. Exams title, date, etc. I'd like to now create a third table Exam results. For this table I believe it should be person ID, exam ID and result, and this is a many to many relationship. @Entity public class ExamResult { private Exam exam; private Person person; private double value; @Id @ManyToOne( cascade = {CascadeType.PERSIST, CascadeType.MERGE} ) @JoinColumn(name="EXAM_ID") public Exam getExam() { return exam; } public void setExam(Exam exam) { this.exam = exam; } @Id @ManyToOne( cascade = {CascadeType.PERSIST, CascadeType.MERGE} ) @JoinColumn(name="PERSON_ID") public Person getPerson() { return person; } public void setPerson(Person person) { this.person = person; } public double getValue() { return value; } public void setValue(double value) { this.value = value; } } The error: org.hibernate.MappingException: Could not determine type for: Person, at table: ExamResult, for columns: [org.hibernate.mapping.Column(person)] I think I may be going about this the wrong way, but I can't work out how to proceed with this relationship from the tutorial. Any ideas?

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  • one page filter results in new page in javascript

    - by Jake
    I have links set up on one page and the relationship between the links is a parent child relationship. (For example: Parent: All, Children: Software; Hardware) These links of course lead the user to a new page that shows the results from a table that is populated. Currently these links are all Similar destinations, but just a filter in the url. But the problem is that there is a javascript filter on the page that gives the user to choose between All, Software, or Hardware. Understand basically that if the url is still reading that there on the software page but they just filtered on the page to be Hardware that doesn't look good IMO. So what I was trying to do was make the links on the inital page all go the the exact same destination and somehow still know on the new page which link was clicked and run the javascript filter from knowing which link was clicked on that page. Is there a way to found that out from javascript? I guess a way to pass that value to the new page and retrieving it in javascript without showing it in the url so I can filter the table for the user based on that value?

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  • Linq-to-sql Add item and a one-to-many record at once

    - by Oskar Kjellin
    I have a function where I can add articles and users can comment on them. This is done with a one to many relationship like= "commentId=>ArticleId". However when I try to add the comment to the database at the same time as I add the one to many record, the commentId is not known. Like this code: Comment comment = new Comment(); comment.Date = DateTime.UtcNow; comment.Text = text; comment.UserId = userId; db.Comments.InsertOnSubmit(comment); comment.Articles.Add(new CommentsForArticle() { ArticleId = articleId, CommentId = comment.CommentId }); The commentId will be 0 before i press submit. Is there any way arround not having to submit in between or do I simply have to cut out the part where I have a one-to-many relationship and just use a CommentTable with a column like "ArticleId". What is best in a performance perspective? I understand the underlying issue, I just want to know which solution works best.

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  • Got a table of people, who I want to link to each other, many-to-many, with the links being bidirect

    - by dflock
    Imagine you live in very simplified example land - and imagine that you've got a table of people in your MySQL database: create table person ( person_id int, name text ) select * from person; +-------------------------------+ | person_id | name | +-------------------------------+ | 1 | Alice | | 2 | Bob | | 3 | Carol | +-------------------------------+ and these people need to collaborate/work together, so you've got a link table which links one person record to another: create table person__person ( person__person_id int, person_id int, other_person_id int ) This setup means that links between people are uni-directional - i.e. Alice can link to Bob, without Bob linking to Alice and, even worse, Alice can link to Bob and Bob can link to Alice at the same time, in two separate link records. As these links represent working relationships, in the real world they're all two-way mutual relationships. The following are all possible in this setup: select * from person__person; +---------------------+-----------+--------------------+ | person__person_id | person_id | other_person_id | +---------------------+-----------+--------------------+ | 1 | 1 | 2 | | 2 | 2 | 1 | | 3 | 2 | 2 | | 4 | 3 | 1 | +---------------------+-----------+--------------------+ For example, with person__person_id = 4 above, when you view Carol's (person_id = 3) profile, you should see a relationship with Alice (person_id = 1) and when you view Alice's profile, you should see a relationship with Carol, even though the link goes the other way. I realize that I can do union and distinct queries and whatnot to present the relationships as mutual in the UI, but is there a better way? I've got a feeling that there is a better way, one where this issue would neatly melt away by setting up the database properly, but I can't see it. Anyone got a better idea?

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  • Combining multiple content types into a single search result with Drupal 6 and Views 2

    - by Chaulky
    Hi all, I need to create a somewhat advanced search functionality for my Drupal 6 site. I have a one-to-many relationship between two content types and need to search them, respecting that relationship. To make things more clear... I have content types TypeX and TypeY. TypeY has a node reference CCK field that relates it to a single node of TypeX. So, many nodes of TypeY reference the same node of TypeX. I want to use Views 2 to create a search page for these nodes. I want each search result to be a node of TypeX, along with all the nodes of TypeY that reference it. I know I could just theme the individual results and use a view to add the nodes of TypeY to the single node of TypeX... but that won't allow users to actually search TypeY... it would only search TypeX and merely display some nodes of TypeY along with it. Is there anyway to get the search to account for content in nodes of both content types, but merge the TypeY results into the "parent" node of TypeX? In database terms, it seems like I need to do a join, then filter by the search terms. But I can't figure out how to do this in Views. Thanks for any help i can get!!!

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  • sqlalchemy relation through another (declarative)

    - by clayg
    Is anyone familiar with ActiveRecord's "has_many :through" relations for models? I'm not really a Rails guy, but that's basically what I'm trying to do. As a contrived example consider Projects, Programmers, and Assignments: from sqlalchemy import create_engine from sqlalchemy.orm import sessionmaker from sqlalchemy import Column, ForeignKey from sqlalchemy.types import Integer, String, Text from sqlalchemy.orm import relation from sqlalchemy.ext.declarative import declarative_base Base = declarative_base() class Assignment(Base): __tablename__ = 'assignment' id = Column(Integer, primary_key=True) description = Column(Text) programmer_id = Column(Integer, ForeignKey('programmer.id')) project_id = Column(Integer, ForeignKey('project.id')) def __init__(self, description=description): self.description = description def __repr__(self): return '<Assignment("%s")>' % self.description class Programmer(Base): __tablename__ = 'programmer' id = Column(Integer, primary_key=True) name = Column(String(64)) assignments = relation("Assignment", backref='programmer') def __init__(self, name=name): self.name = name def __repr__(self): return '<Programmer("%s")>' % self.name class Project(Base): __tablename__ = 'project' id = Column(Integer, primary_key=True) name = Column(String(64)) description = Column(Text) assignments = relation("Assignment", backref='project') def __init__(self, name=name, description=description): self.name = name self.description = description def __repr__(self): return '<Project("%s", "%s...")>' % (self.name, self.description[:10]) engine = create_engine('sqlite://') Base.metadata.create_all(engine) Session = sessionmaker(bind=engine) session = Session() Projects have many Assignments. Programmers have many Assignments. (understatement?) But in my office at least, Programmers also have many Projects - I'd like this relationship to be inferred through the Assignments assigned to the Programmer. I'd like the Programmer model to have a attribute "projects" which will return a list of Projects associated to the Programmer through the Assignment model. me = session.query(Programmer).filter_by(name='clay').one() projects = session.query(Project).\ join(Project.assignments).\ join(Assignment.programmer).\ filter(Programmer.id==me.id).all() How can I describe this relationship clearly and simply using the sqlalchemy declarative syntax? Thanks!

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  • Setting attributes of a class during construction from **kwargs

    - by Carson Myers
    Python noob here, Currently I'm working with SQLAlchemy, and I have this: from __init__ import Base from sqlalchemy.schema import Column, ForeignKey from sqlalchemy.types import Integer, String from sqlalchemy.orm import relationship class User(Base): __tablename__ = "users" id = Column(Integer, primary_key=True) username = Column(String, unique=True) email = Column(String) password = Column(String) salt = Column(String) openids = relationship("OpenID", backref="users") User.__table__.create(checkfirst=True) #snip definition of OpenID class def create(**kwargs): user = User() if "username" in kwargs.keys(): user.username = kwargs['username'] if "email" in kwargs.keys(): user.username = kwargs['email'] if "password" in kwargs.keys(): user.password = kwargs['password'] return user This is in /db/users.py, so it would be used like: from db import users new_user = users.create(username="Carson", password="1234") new_user.email = "[email protected]" users.add(new_user) #this function obviously not defined yet but the code in create() is a little stupid, and I'm wondering if there's a better way to do it that doesn't require an if ladder, and that will fail if any keys are added that aren't in the User object already. Like: for attribute in kwargs.keys(): if attribute in User: user.__attribute__[attribute] = kwargs[attribute] else: raise Exception("blah") that way I could put this in its own function (unless one hopefully already exists?) So I wouldn't have to do the if ladder again and again, and so I could change the table structure without modifying this code. Any suggestions?

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  • Can you have a Dynamic Data Field which consists of a list of fields?

    - by Telos
    This is a purely theoretical question (at least until I start trying to implement it) but here goes. I wrote a web form a long time ago which has a configurable section for getting information. Basically for some customers there are no fields, for other customers there are up to 20 fields. I got it working by dynamically creating the fields at just the right time in the page lifecycle and going through a lot of headaches. 2 years later, I need to make some pretty big updates to this web form and there are some nifty new technologies. I've worked with ASP.NET Dynamic Data just a bit and, well, I half-crazed plan just occurred to me: The Ticket object has a one-to-many relationship to ExtendedField, we'll call that relationship Fields for brevity. Using that, the idea would be to create a FieldTemplate that dynamically generated the list of fields and displayed it. The big questions here would probably be: 1) Can a single field template resolve to multiple web controls without breaking things? 2) Can dynamic data handle updating/inserting multiple rows in such a fashion? 3) There was a third question I had a few minutes ago, but coworkers interrupted me and I forgot. So now the third question is: what is the third question? So basically, does this sound like it could work or am I missing a better/more obvious solution?

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  • PHP: Need help with simple XML

    - by Jack
    I am beginner in PHP. I am trying to parse this xml file. <relationship> <target> <following type="boolean">true</following> <followed_by type="boolean">true</followed_by> <screen_name>xxxx</screen_name> <id type="integer">xxxx</id> </target> <source> <notifications_enabled nil="true"/> <following type="boolean">true</following> <blocking nil="true"/> <followed_by type="boolean">true</followed_by> <screen_name>xxxx</screen_name> <id type="integer">xxxxx</id> </source> </relationship> I need to get the value of the field 'following type="boolean" ' for the target and here's my code - $xml = simplexml_load_string($response); foreach($xml->children() as $child) { if ($child->getName() == 'target') { foreach($child->children() as $child_1) if ( $child_1->getName() == 'following') { $is_my_friend = (bool)$child_1; break; } break; } } but I am not getting the correct output. I think the ' type="boolean" ' part of the field is creating problems. Please help.

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  • Linked Measure Groups and Local Dimensions

    - by ekoner
    Mulling over something I've been reading up on. According to Chris Webb, A linked measure group can only be used with dimensions from the same database as the source measure group. So I took this to mean as long as two cubes share a database, a linked measure group can be used with a dimension. So I created a new cube and added a local measure group, a local dimension and a linked measure group. However, I can't create a relationship between the linked measure group and the local dimension even though they are within the same database. I get the message below: Regular relationships in the current database between non-linked (local) dimensions and linked measure groups cannot be edited. These relationship can only be created through the wizard. This dialog can be used to delete these relationships. I see that I can go to the original cube and add the dimension there, but does the message below mean I have an alternative? I just know it's going to be something simple and trivial! Thanks for reading.

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  • In a bidirectional JPA OneToMany/ManyToOne association, what is meant by "the inverse side of the as

    - by Bytecode Ninja
    In these examples on TopLink JPA Annotation Reference: Example 1-59 @OneToMany - Customer Class With Generics @Entity public class Customer implements Serializable { ... @OneToMany(cascade=ALL, mappedBy="customer") public Set<Order> getOrders() { return orders; } ... } Example 1-60 @ManyToOne - Order Class With Generics @Entity public class Order implements Serializable { ... @ManyToOne @JoinColumn(name="CUST_ID", nullable=false) public Customer getCustomer() { return customer; } ... } It seams to me that the Customer entity is the owner of the association. However, in the explanation for the mappedBy attribute in the same document, it is written that: if the relationship is bidirectional, then set the mappedBy element on the inverse (non-owning) side of the association to the name of the field or property that owns the relationship as Example 1-60 shows. However, if I am not wrong, looks like in the example the mappedBy is actually specified on the owning side of the association, rather than the non-owning side. So my question is basically: In a bidirectional (one-to-many/many-to-one) association, which of the entities is the owner? How can we designate the One side as the owner? How can we designate the Many side as the owner? What is meant by "the inverse side of the association"? How can we designate the One side as the inverse? How can we designate the Many side as the inverse? Thanks in advance.

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  • Acceessing some aggregate functions in a linq datasource in a GridView

    - by Stephen Pellicer
    I am working on a traditional WebForms project. In the project I am trying out some Linq datasources with plans to eventually migrate to an MVC architecture. I am still very new to Linq. I have a GridView using a Linq datasource. The entities I am showing has a to many relationship and I would like to get the maximum value of a column in the many side of the relationship. I can show properties of the base entity in the gridview: <asp:TemplateField HeaderText="Number" SortExpression="tJobBase.tJob.JobNumber"> <ItemTemplate> <asp:Label ID="Label1" runat="server" Text='<%# Bind("tJobBase.tJob.JobNumber") %>'> </asp:Label> </ItemTemplate> </asp:TemplateField> I can also show the count of the many related property: <asp:TemplateField HeaderText="Number" SortExpression="tJobBase.tJob.tHourlies.Count"> <ItemTemplate> <asp:Label ID="Label1" runat="server" Text='<%# Bind("tJobBase.tJob.tHourlies.Count") %>'> </asp:Label> </ItemTemplate> </asp:TemplateField> Is there a way to get the max value of a column called WeekEnding in the tHourlies collection to show in the GridView?

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  • Understanding many to many relationships and Entity Framework

    - by Anders Svensson
    I'm trying to understand the Entity Framework, and I have a table "Users" and a table "Pages". These are related in a many-to-many relationship with a junction table "UserPages". First of all I'd like to know if I'm designing this relationship correctly using many-to-many: One user can visit multiple pages, and each page can be visited by multiple users..., so am I right in using many2many? Secondly, and more importantly, as I have understood m2m relationships, the User and Page tables should not repeat information. I.e. there should be only one record for each user and each page. But then in the entity framework, how am I able to add new visits to the same page for the same user? That is, I was thinking I could simply use the Count() method on the IEnumerable returned by a LINQ query to get the number of times a user has visited a certain page. But I see no way of doing that. In Linq to Sql I could access the junction table and add records there to reflect added visits to a certain page by a certain user, as many times as necessary. But in the EF I can't access the junction table. I can only go from User to a Pages collection and vice versa. I'm sure I'm misunderstanding relationships or something, but I just can't figure out how to model this. I could always have a Count column in the Page table, but as far as I have understood you're not supposed to design database tables like that, those values should be collected by queries... Please help me understand what I'm doing wrong...

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  • how can I save/keep-in-sync an in-memory graph of objects with the database?

    - by Greg
    Question - What is a good best practice approach for how can I save/keep-in-sync an jn-memory graph of objects with the database? Background: That is say I have the classes Node and Relationship, and the application is building up a graph of related objects using these classes. There might be 1000 nodes with various relationships between them. The application needs to query the structure hence an in-memory approach is good for performance no doubt (e.g. traverse the graph from Node X to find the root parents) The graph does need to be persisted however into a database with tables NODES and RELATIONSHIPS. Therefore what is a good best practice approach for how can I save/keep-in-sync an jn-memory graph of objects with the database? Ideal requirements would include: build up changes in-memory and then 'save' afterwards (mandatory) when saving, apply updates to database in correct order to avoid hitting any database constraints (mandatory) keep persistence mechanism separate from model, for ease in changing persistence layer if needed, e.g. don't just wrap an ADO.net DataRow in the Node and Relationship classes (desirable) mechanism for doing optimistic locking (desirable) Or is the overhead of all this for a smallish application just not worth it and I should just hit the database each time for everything? (assuming the response times were acceptable) [would still like to avoid if not too much extra overhead to remain somewhat scalable re performance]

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  • With this generics code why am I getting "Argument 1: cannot convert from 'ToplogyLibrary.Relationsh

    - by Greg
    Hi, Any see why I'm getting a "Argument 1: cannot convert from 'ToplogyLibrary.RelationshipBase' to 'TRelationship'" in the code below, in CreateRelationship() ? public class TopologyBase<TKey, TNode, TRelationship> where TNode : NodeBase<TKey>, new() where TRelationship : RelationshipBase<TKey>, new() { // Properties public Dictionary<TKey, TNode> Nodes { get; private set; } public List<TRelationship> Relationships { get; private set; } // Constructors protected TopologyBase() { Nodes = new Dictionary<TKey, TNode>(); Relationships = new List<TRelationship>(); } // Methods public TNode CreateNode(TKey key) { var node = new TNode {Key = key}; Nodes.Add(node.Key, node); return node; } public void CreateRelationship(TNode parent, TNode child) { // Validation if (!Nodes.ContainsKey(parent.Key) || !Nodes.ContainsKey(child.Key)) { throw new ApplicationException("Can not create relationship as either parent or child was not in the graph: Parent:" + parent.Key + ", Child:" + child.Key); } // Add Relationship var r = new RelationshipBase<TNode>(); r.Parent = parent; r.Child = child; Relationships.Add(r); // *** HERE *** "Argument 1: cannot convert from 'ToplogyLibrary.RelationshipBase<TNode>' to 'TRelationship'" } } public class RelationshipBase<TNode> { public TNode Parent { get; set; } public TNode Child { get; set; } } public class NodeBase<T> { public T Key { get; set; } public NodeBase() { } public NodeBase(T key) { Key = key; } }

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  • Managing inverse relationships without CoreData

    - by Nathaniel Martin
    This is a question for Objective-J/Cappuccino, but I added the cocoa tag since the frameworks are so similar. One of the downsides of Cappuccino is that CoreData hasn't been ported over yet, so you have to make all your model objects manually. In CoreData, your inverse relationships get managed automatically for you... if you add an object to a to-many relationship in another object, you can traverse the graph in both directions. Without CoreData, is there any clean way to setup those inverse relationships automatically? For a more concrete example, let's take the typical Department and Employees example. To use rails terminology, a Department object has-many Employees, and an Employee belongs-to a Department. So our Department model has an NSMutableSet (or CPMutableSet ) "employees" that contains a set of Employees, and our Employee model has a variable "department" that points back to the Department model that owns it. Is there an easy way to make it so that, when I add a new Employee model into the set, the inverse relationship (employee.department) automatically gets set? Or the reverse: If I set the department model of an employee, then it automatically gets added to that department's employee set? Right know I'm making an object, "ValidatedModel" that all my models subclass, which adds a few methods that setup the inverse relationships, using KVO. But I'm afraid that I'm doing a lot of pointless work, and that there's already an easier way to do this. Can someone put my concerns to rest?

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  • Core Data: migrating entities with self-referential properties

    - by Dan
    My Core Data model contains an entity, Shape, that has two self-referential relationships, which means four properties. One pair is a one-to-many relationship (Shape.containedBy <- Shape.contains) and the another is a many-to-many relationship (Shape.nextShapes <<- Shape.previousShapes). It all works perfectly in the application, so I don't think self-referencing relationships is a problem in general. However, when it comes to migrating the model to a new version, then Xcode fails to compile the automatically generated mapping model, with this error message: 2009-10-30 17:10:09.387 mapc[18619:607] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: 'Unable to parse the format string "FUNCTION($manager ,'destinationInstancesForSourceRelationshipNamed:sourceInstances:' , 'contains' , $source.contains) == 1"' *** Call stack at first throw: ( 0 CoreFoundation 0x00007fff80d735a4 __exceptionPreprocess + 180 1 libobjc.A.dylib 0x00007fff83f0a313 objc_exception_throw + 45 2 Foundation 0x00007fff819bc8d4 _qfqp2_performParsing + 8412 3 Foundation 0x00007fff819ba79d +[NSPredicate predicateWithFormat:arguments:] + 59 4 Foundation 0x00007fff81a482ef +[NSExpression expressionWithFormat:arguments:] + 68 5 Foundation 0x00007fff81a48843 +[NSExpression expressionWithFormat:] + 155 6 XDBase 0x0000000100038e94 -[XDDevRelationshipMapping valueExpressionAsString] + 260 7 XDBase 0x000000010003ae5c -[XDMappingCompilerSupport generateCompileResultForMappingModel:] + 2828 8 XDBase 0x000000010003b135 -[XDMappingCompilerSupport compileSourcePath:options:] + 309 9 mapc 0x0000000100001a1c 0x0 + 4294973980 10 mapc 0x0000000100001794 0x0 + 4294973332 ) terminate called after throwing an instance of 'NSException' Command /Developer/usr/bin/mapc failed with exit code 6 The 'contains' is the name of one of the self-referential properties. Anyway, the really big problem is that I can't even look at this Mapping Property as Xcode crashes as soon as I select the entity mapping when viewing the mapping model. So I'm a bit lost really where to go from here. I really can't remove the self-referential properties, so I'm thinking I've got manually create a mapping model that compiles? Any ideas? Cheers

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  • How to properly set relationships in Core Data when using setValue and data already exists

    - by ern
    Let's say I have two objects: Articles and Categories. For the sake of this example all relevant categories have already been added to the data store. When looping through data that holds edits for articles, there is category relationship information that needs to be saved. I was planning on using the -setValue method in the Article class in order to set the relationships like so: - (void)setValue:(id)value forUndefinedKey:(NSString *)key { if([key isEqualToString:@"categories"]){ NSLog(@"trying to set categories..."); } } The problem is that value isn't a Category, it is just a string (or array of strings) holding the title of a category. I could certainly do a lookup within this method for each category and assign it, but that seems inefficient when processing a whole bunch of articles at once. Another option is to populate an array of all possible categories and just filter, but my question is where to store that array? Should it be a class method on Article? Is there a way to pass in additional data to the -setValue method? Is there another, better option for setting the relationship I'm not thinking of? Thanks for your help.

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  • JoinColumn name not used in sql

    - by Vladimir
    Hi! I have a problem with mapping many-to-one relationship without exact foreign key constraint set in database. I use OpenJPA implementation with MySql database, but the problem is with generated sql scripts for insert and select statements. I have LegalEntity table which contains RootId column (among others). I also have Address table which has LegalEntityId column which is not nullable, and which should contain values referencing LegalEntity's "RootId" column, but without any database constraint (foreign key) set. Address entity is mapped: @Entity @Table(name="address") public class Address implements Serializable { ... @ManyToOne(fetch=FetchType.LAZY, optional=false) @JoinColumn(referencedColumnName="RootId", name="LegalEntityId", nullable=false, insertable=true, updatable=true, table="LegalEntity") public LegalEntity getLegalEntity() { return this.legalEntity; } } SELECT statement (when fetching LegalEntity's addresses) and INSERT statment are generated: SELECT t0.Id, .., t0.LEGALENTITY_ID FROM address t0 WHERE t0.LEGALENTITY_ID = ? ORDER BY t0.Id DESC [params=(int) 2] INSERT INTO address (..., LEGALENTITY_ID) VALUES (..., ?) [params=..., (int) 2] If I omit table attribute from mentioned statements are generated: SELECT t0.Id, ... FROM address t0 INNER JOIN legalentity t1 ON t0.LegalEntityId = t1.RootId WHERE t1.Id = ? ORDER BY t0.Id DESC [params=(int) 2] INSERT INTO address (...) VALUES (...) [params=...] So, LegalEntityId is not included in any of the statements. Is it possible to have relationship based on such referencing (to column other than primary key, without foreign key in database)? Is there something else missing? Thanks in advance.

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