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  • Triangulation in 3D Space

    - by w3b_wizzard
    Disclaimer: This is for class, however I'm fresh out of ideas and a nudge in the right direction would be much appreciated. Also, this needs to be implemented in raw C, so no fancy libraries can be used. I have to write a search and rescue simulator for submarines, it has to find a probe that is randomly placed in 3D space in a grid from of the MAX_XYZ (100000). The only tools I'm given are a "ping" which will give the magnitude of the distance between a certain sub and the probe. The goal is to optimize the costs of this entire operation so a brute force attempt, like looking at every single coordinate, won't work. Hence I was thinking triangulation. Now, it makes loads of sense to me, place three subs, each one of them uses their ping to get the distance between them and the probe. Since each sub have a known distance relative to one another, it's easy to build the base of a tetrahedron with them, and the results of the ping will point to a certain coordinate, the problem I'm having is how to figure out the elevation, or the height, of the tetrahedron. So what I have as data is the following: Distances between subs (In vector format) Angles between each subs (very easy to compute) Distance between each sub and the probe (3 segments from the base to the peak) Angles inside each of the outer 3 surfaces of the tetrahedron. I tried finding some sort of relationship with the vertices of the tetrahedron and the relative angles in each of them, however all I found had to deal with tetrahedrons built with equilateral triangles, which isn't much help. I have the impression this can be easily solved with trig but either I'm not seeing it or I need more coffee. Any suggestions would be appreciated!

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  • Saving Data to Relational Database (Entity Framework)

    - by sheefy
    I'm having a little bit of trouble saving data to a database. Basically, I have a main table that has associations to other tables (Example Below). Tbl_Listing ID UserID - Associated to ID in User Table CategoryID - Associated to ID in Category Table LevelID - Associated to ID in Level Table. Name Address Normally, it's easy for me to add data to the DB (using Entity Framework). However, I'm not sure how to add data to the fields with associations. The numerous ID fields just need to hold an int value that corresponds with the ID in the associated table. For example; when I try to access the column in the following manner I get a "Object reference not set to an instance of an object." error. Listing NewListing = new Listing(); NewListing.Tbl_User.ID = 1; NewListing.Tbl_Category.ID = 2; ... DBEntities.AddToListingSet(NewListing); DBEntities.SaveChanges(); I am using NewListing.Tbl_User.ID instead of NewListing.UserID because the UserID field is not available through intellisense. If I try and create an object for each related field I get a "The relationship between the two objects cannot be defined because they are attached to different ObjectContext objects." error. With this method, I am trying to add the object without the .ID shown above - example NewListing.User = UserObject. I know this should be simple as I just want to reference the ID from the associated table in the main Listing's table. Any help would be greatly appreciated. Thanks in advance, -S

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  • Mapping many-to-many association table with extra column(s)

    - by user635524
    My database contains 3 tables: User and Service entities have many-to-many relationship and are joined with the SERVICE_USER table as follows: USERS - SERVICE_USER - SERVICES SERVICE_USER table contains additional BLOCKED column. What is the best way to perform such a mapping? These are my Entity classes @Entity @Table(name = "USERS") public class User implements java.io.Serializable { private String userid; private String email; @Id @Column(name = "USERID", unique = true, nullable = false,) public String getUserid() { return this.userid; } .... some get/set methods } @Entity @Table(name = "SERVICES") public class CmsService implements java.io.Serializable { private String serviceCode; @Id @Column(name = "SERVICE_CODE", unique = true, nullable = false, length = 100) public String getServiceCode() { return this.serviceCode; } .... some additional fields and get/set methods } I followed this example http://giannigar.wordpress.com/2009/09/04/m ... using-jpa/ Here is some test code: User user = new User(); user.setEmail("e2"); user.setUserid("ui2"); user.setPassword("p2"); CmsService service= new CmsService("cd2","name2"); List<UserService> userServiceList = new ArrayList<UserService>(); UserService userService = new UserService(); userService.setService(service); userService.setUser(user); userService.setBlocked(true); service.getUserServices().add(userService); userDAO.save(user); The problem is that hibernate persists User object and UserService one. No success with the CmsService object I tried to use EAGER fetch - no progress Is it possible to achieve the behaviour I'm expecting with the mapping provided above? Maybe there is some more elegant way of mapping many to many join table with additional column?

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  • Entity Framework EntityKey / Foreign Key problem.

    - by Ronny176
    Hi, I keep getting the same error: Entities in 'VlaamseOverheidMeterEntities.ObjectMeter' participate in the 'FK_ObjectMeter_Meter' relationship. 0 related 'Meter' were found. 1 'Meter' is expected. I have the following table structure: Meter 1 <- * ObjectMeter * - 1 VO_Object It is always the same scenario: The first meter is added to the database, the second meter gives the error above. I have the following code in my manager: public List<string> addTemporary(string username, string meterNaam, string readingType, string parentID) { Meter meter = new Meter(); VO_Object voObject = objectManager.getObjectByID(parentID); ObjectMeter objMeter = new ObjectMeter(); meter.readingType = (int)Enum.Parse(typeof(ReadingType), readingType); meter.isActive = true; meter.name = meterNaam; meter.startDate = DateTime.Now; meter.endDate = DateTime.Now.AddYears(6000); meter.uniqueIdentifier = "N/A"; meter.meterType = (int)Enum.Parse(typeof(MeterType), "NA"); meter.meterCategory = (int)Enum.Parse(typeof(MeterCategory), "NA"); meter.energyType = (int)Enum.Parse(typeof(EnergyType), "NA"); meter.utilityType = (int)Enum.Parse(typeof(UtilityType), "NA"); meter.unitOfMeasure = (int)Enum.Parse(typeof(UnitOfMeasure), "NA"); objMeter.valid_from = meter.startDate; objMeter.valid_until = meter.endDate; objMeter.Meter = meter; objMeter.VO_Object = voObject; createMeter(meter); List<String> str = new List<string>(); str.Add("" + meter.meterID); str.Add(meter.name); return str; } and this in my Dao Class which links to the database: internal void CreateMeter(Meter _meter) { _entities.AddToMeter(_meter); _entities.SaveChanges(); } Can someone please explain this error? Ronald

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  • Core Data combined Query

    - by Chris Summer
    Hey, i have question related to CoreData. My iphone project has 2 Entities, Organisation and Brand with a 1 to many "BrandsToOrg" relationship and inverse. So my project has a Mapview, where you can see all the Organisations and a little subview when you click on those Organisations.At the subview there is a "show Brands" Button, which should init a new TableView who only shows the brands belong to the seleceted organisation. Any ideas how i can code that? thx NSPredicate *predicate = [NSPredicate predicateWithFormat: @"(TitleMedium == %@)",@"Rock Antenne"];???? NSFetchRequest *request = [[NSFetchRequest alloc] init]; NSEntityDescription *entity = [NSEntityDescription entityForName:self.entityName inManagedObjectContext:managedObjectContext]; [request setEntity:entity]; // If a predicate was passed, pass it to the query if(predicate != nil) { [request setPredicate:predicate]; } // If a sort key was passed, use it for sorting. NSString *sortKey=@"TitleMedium"; BOOL sortAscending=YES; if(sortKey != nil) { NSSortDescriptor *sortDescriptor = [[NSSortDescriptor alloc] initWithKey:sortKey ascending:sortAscending]; NSArray *sortDescriptors = [[NSArray alloc] initWithObjects:sortDescriptor, nil]; [request setSortDescriptors:sortDescriptors]; [sortDescriptors release]; [sortDescriptor release]; } NSError *error; NSMutableArray *mutableFetchResults = [[managedObjectContext executeFetchRequest:request error:&error] mutableCopy]; [request release]; [self setEntityArray:mutableFetchResults];

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  • Modeling Buyers & Sellers in a Rails Ecommerce App

    - by MikeH
    I'm building a Rails app that has Etsy.com style functionality. In other words, it's like a mall. There are many buyers and many sellers. I'm torn about how to model the sellers. Key facts: There won't be many sellers. Perhaps less than 20 sellers in total. There will be many buyers. Hopefully many thousands :) I already have a standard user model in place with account creation and roles. I've created a 'role' of 'seller', which the admin will manually apply to the proper users. Since we'll have very few sellers, this is not an issue. I'm considering two approaches: (1) Create a 'store' model, which will contain all the relevant store information. Products would :belong_to :store, rather than belonging to the seller. The relationship between the user and store models would be: user :has_one store. My main problem with this is that I've always found has_one associations to be a little funky, and I usually try to avoid them. The app is fairly complex, and I'm worried about running into a cascade of problems connected to the has_one association as I get further along into development. (2) Simply include the relevant 'store' information as part of the user model. But in this case, the store-related db columns would only apply to a very small percentage of users since very few users will also be sellers. I'm not sure if this is a valid concern or not. It's very possible that I'm thinking about this incorrectly. I appreciate any thoughts. Thanks.

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  • Creating nested fields for column on assignment table?

    - by H O
    I have three models, that represent a many to many relationship - Product, Sale and Product_sale. I have a nested form that allows me to create new products from the sale form - so far, so good. I have, however, added some additional fields to the assignment table - price, for example. How can I set the price on the assignment table from the product form, when it is nested in the sale form? I currently have the code below: <%= sale.fields_for :products do |products_builder| %> <%= render :partial => "products/form", :locals => {:f => products_builder, :form_actions_visible => false} %> <% end -%> I could nest a Product_sale form within the product form, but this would create a new product_sale, which is not what I am looking for. I will most likely need to nest the price field within the product form, to ensure that it updates the correct assignment record (since there could be multiple products on one sale form). How can I use a fields_for loop on the product form to update the existing assignment record that is built when I do @sale.products.build? The assignment record will not yet be saved, so I can not access it using a where clause and edit it that way. Thanks!

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  • NHibernate with string primary key and relationships

    - by John_
    I've have just been stumped with this problem for an hour and I annoyingly found the problem eventually. THE CIRCUMSTANCES I have a table which users a string as a primary key, this table has various many to one and many to many relationships all off this primary key. When searching for multiple items from the table all relationships were brought back. However whenever I tried to get the object by the primary key (string) it was not bringing back any relationships, they were always set to 0. THE PARTIAL SOLUTION So I looked into my logs to see what the SQL was doing and that was returning the correct results. So I tried various things in all sorts of random ways and eventually worked out it was. The case of the string being passed into the get method was not EXACTLY the same case as it was in the database, so when it tried to match up the relationship items with the main entity it was finding nothing (Or at least NHIbernate wasn't because as I stated above the SQL was actually returning the correct results) THE REAL SOLUTION Has anyone else come across this? If so how do you tell NHibernate to ignore case when matching SQL results to the entity? It is silly because it worked perfectly well before now all of a sudden it has started to pay attention to the case of the string.

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  • [PHP/MySQL] How to create text diff web app

    - by Adam Kiss
    Hello, idea I would like to create a little app for myself to store ideas (the thing is - I want it to do MY WAY) database I'm thinking going simple: id - unique id of revision in database text_id - identification number of text rev_id - number of revision flags - various purposes - expl. later title - self expl. desc - description text - self expl . flags - if I (i.e.) add flag rb;65, instead of storing whole text, I just said, that whenever I ask for latest revision, I go again in DB and check revision 65 Question: Is this setup the best? Is it better to store the diff, or whole text (i know, place is cheap...)? Does that revision flag make sense (wouldn't it be better to just copy text - more disk space, but less db and php processing. php I'm thinking, that I'll go with PEAR here. Although main point is to open-edit-save, possiblity to view revisions can't be that hard to program and can be life-saver in certain situations (good ideas got deleted, saving wrong version, etc...). However, I've never used PEAR in a long-time or full-project relationship, however, brief encounters in my previous experience left rather bad feeling - as I remember, it was too difficult to implement, slow and humongous to play with, so I don't know, if there's anything better. why? Although there are bazillions of various time/project/idea management tools, everything lacks something for me, whether it's sharing with users, syncing on more PCs, time-tracking, project management... And I believe, that this text diff webapp will be for internal use with various different tools later. So if you know any good and nice-UI-having project management app with support for text-heavy usage, just let me know, so I'll save my time for something better than redesigning the weel.

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  • Low Throughput on Windows Named Pipe Over WAN

    - by MichaelB76
    I'm having problems with low performance using a Windows named pipe. The throughput drops off rapidly as the network latency increases. There is a roughly linear relationship between messages sent per second and round trip time. It seems that the client must ack each message before the server will send the next one. This leads to very poor performance, I can only send 5 (~100 byte) messages per second over a link with an RTT of 200 ms. The pipe is asynchronous, using multiple overlapped write operations (and multiple overlapped reads at the client end), but this is not improving throughput. Is it possible to send messages in parallel over a named pipe? The pipe is created using PIPE_TYPE_MESSAGE, would PIPE_READMODE_BYTE work better? Is there any other way I can improve performance? This is a deployed solution, so I can't simply replace the pipe with a socket connection (I've read that Windows named pipe aren't recommended for use over a WAN, and I'm wondering if this is why). I'd be grateful for any help with this matter.

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  • Joining tables with composite keys in a legacy system in hibernate

    - by Steve N
    Hi, I'm currently trying to create a pair of Hibernate annotated classes to load (read only) from a pair of tables in a legacy system. The legacy system uses a consistent (if somewhat dated) approach to keying tables. The tables I'm attempting to map are as follows: Customer CustomerAddress -------------------------- ---------------------------- customerNumber:string (pk) customerNumber:string (pk_1) name:string sequenceNumber:int (pk_2) street:string postalCode:string I've approached this by creating a CustomerAddress class like this: @Entity @Table(name="CustomerAddress") @IdClass(CustomerAddressKey.class) public class CustomerAddress { @Id @AttributeOverrides({ @AttributeOverride(name = "customerNumber", column = @Column(name="customerNumber")), @AttributeOverride(name = "sequenceNumber", column = @Column(name="sequenceNumber")) }) private String customerNumber; private int sequenceNumber; private String name; private String postalCode; ... } Where the CustomerAddressKey class is a simple Serializable object with the two key fields. The Customer object is then defined as: @Entity @Table(name = "Customer") public class Customer { private String customerNumber; private List<CustomerAddress> addresses = new ArrayList<CustomerAddress>(); private String name; ... } So, my question is: how do I express the OneToMany relationship on the Customer table?

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  • MySQL Join Question

    - by rbaker86
    Hi i'm struggling to write a particular MySQL Join Query. I have a table containing product data, each product can belong to multiple categories. This m:m relationship is satisfied using a link table. For this particular query I wish to retrieve all products belonging to a given category, but with each product record, I also want to return the other categories that product belongs to. Ideally I would like to achieve this using an Inner Join on the categories table, rather than performing an additional query for each product record, which would be quite inefficient. My simplifed schema is designed roughly as follows: products table: product_id, name, title, description, is_active, date_added, publish_date, etc.... categories table: category_id, name, title, description, etc... product_category table: product_id, category_id I have written the following query, which allows me to retrieve all the products belonging to the specified category_id. However, i'm really struggling to work out how to retrieve the other categories a product belongs to. SELECT p.product_id, p.name, p.title, p.description FROM prod_products AS p LEFT JOIN prod_product_category AS pc ON pc.product_id = p.product_id WHERE pc.category_id = $category_id AND UNIX_TIMESTAMP(p.publish_date) < UNIX_TIMESTAMP() AND p.is_active = 1 ORDER BY p.name ASC I'd be happy just retrieving the category id's releated to each returned product row, as I will have all category data stored in an object, and my application code can take care of the rest. Many thanks, Richard

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  • UpdatePanel doesn't Refresh

    - by mrxrsd
    I have got a simple page with a HtmlInputHidden field. I use Javascript to update that value and, when posting back the page, I want to read the value of that HtmlInputHidden field. The Value property of that HtmlInputHidden field is on postback the default value (the value it had when the page was created, not the value reflected through the Javascript). I also tried to Register the HtmlInputHidden field with ScriptManager.RegisterHiddenField(Page, "MyHtmlImputHiddenField", "initialvalue") but it still only lets me read the 'initialvalue' even though I (through javascript) can inspect that the value has changed. I tried to hardcoded the rowid and, to my surprise, after postback gridview was exactly the same before the delete but the record was deleted from the database. (I´ve called the databind method). protected void gridViewDelete(object sender, GridViewDeleteEventArgs e) { bool bDelete = false; bool bCheck = false; if (hfControl.Value != "1") { // check relationship bCheck = validation_method(.......); if (bCheck) { bDelete = true; } } else { hfControl.Value = ""; bDelete = true; } if (bDelete) { //process delete } else { string script = string.Empty; script += " var x; "; script += " x = confirm('are u sure?'); "; script += " if (x){ " ; script += " document.getElementById('hfControl').value = '1'; "; script += " setTimeOut(__doPostBack('gridView','Delete$" + e.RowIndex + "'),0);"; script += " } "; ScriptManager.RegisterClientScriptBlock(this, Page.GetType() , "confirm" , script ,true); } }

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  • C++ reinterpret cast ?

    - by Ian
    I would like to cast one object of the class PointsList to another object Points3DList (and vice versa) where: template <class T> class PointsList { protected: std::vector <Point <T> *> points; //Only illustration, not possible with templaes }; and template <class T> class Points3DList { protected: std::vector <Point3D<T> *> points; //Only illustration, not possible with templaes }; Between Point and Point3D there is no relationship (inheritance nor composition)... template <class T> class Point { protected: T x; T y; }; template <class T> class Point3D { protected: T x; T y; T z; }; What do you think about conversion Points3DList <T> *pl3D = new Points3DList <T> (); ... PointsList <T> *pl = reinterpret_cast < PointList <T> * > ( pl3D ); where pl3D represents pointer to Points3DList object.. Can reinterpret_cast be used in this case or it is better to create a conversion function? Data model in this case can not be changed...

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  • Doctrine YAML not generating correctly? Or is this markup wrong?

    - by ropstah
    I'm trying to get a many-to-many relationship between Users and Settings. The models seem to be generated correctly, however the following query fails: "User_Setting" with an alias of "us" in your query does not reference the parent component it is related to. $q = new Doctrine_RawSql(); $q->select('{s.*}, {us.*}') ->from('User u CROSS JOIN Setting s LEFT JOIN User_Setting us ON us.usr_auto_key = u.usr_auto_key AND us.set_auto_key = s.set_auto_key') ->addComponent('s', 'Setting s INDEXBY s.set_auto_key') ->addComponent('us', 'User_Setting us') ->where(u.usr_auto_key = ?',$this->usr_auto_key); $this->settings = $q->execute(); Does anyone spot a problem? This is my YAML: User: connection: default tableName: User columns: usr_auto_key: type: integer(4) fixed: false unsigned: false primary: true autoincrement: true notnull: true email: type: string(100) fixed: false unsigned: false primary: false default: '' notnull: true autoincrement: false password: type: string(32) fixed: false unsigned: false primary: false default: '' notnull: true autoincrement: false relations: Setting: class: Setting foreignAlias: User refClass: User_Setting local: usr_auto_key foreign: set_auto_key Setting: connection: default tableName: Setting columns: set_auto_key: type: integer(4) fixed: false unsigned: false primary: true autoincrement: true notnull: true name: type: string(50) fixed: false unsigned: false primary: false notnull: true autoincrement: false User_Setting: connection: default tableName: User_Setting columns: usr_auto_key: type: integer(4) fixed: false unsigned: false primary: true autoincrement: false notnull: true set_auto_key: type: integer(4) fixed: false unsigned: false primary: true autoincrement: false notnull: true value: type: string(255) fixed: false unsigned: false primary: false notnull: true autoincrement: false relations: Setting: foreignAlias: User_Setting local: set_auto_key foreign: set_auto_key User: foreignAlias: User_Setting local: usr_auto_key foreign: usr_auto_key

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  • IEnumerator seems to be effecting all objects, and not one at a time

    - by PFranchise
    Hey, I am trying to alter an attribute of an object. I am setting it to the value of that same attribute stored on another table. There is a one to many relationship between the two. The product end is the one and the versions is the many. Right now, both these methods that I have tried have set all the products returned equal to the final version object. So, in this case they are all the same. I am not sure where the issue lies. Here are my two code snipets, both yield the same result. int x = 1 IEnumerator<Product> ie = productQuery.GetEnumerator(); while (ie.MoveNext()) { ie.Current.RSTATE = ie.Current.Versions.First(o => o.VersionNumber == x).RSTATE; x++; } and foreach (var product in productQuery) { product.RSTATE = product.Versions.Single(o => o.VersionNumber == x).RSTATE; x++; } The versions table holds information for previous products, each is distinguished by the version number. I know that it will start at 1 and go until it reaches the current version, based on my query returning the proper number of products. Thanks for any advice.

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  • EF4 querying through the generations

    - by Hans Kesting
    I have a model withs Parents, Children and Grandchildren, in a many-to-many relationship. Using this article I created POCO classes that work fine, except for one thing I can't yet figure out. When I query the Parents or Children directly using LINQ, the SQL reflects the LINQ query (a .Count() executes a COUNT in the database and so on) - fine. The Parent class has a Children property, to access it's children. But (and now for the problem) this doesn't expose an IQueryable interface but an ICollection. So when I access the Children property on a particular parent all the Parent's Children are read. Even worse, when I access the Grandchildren (theParent.Children.SelectMany(child => child.GrandChildren).Count()) then for each and every child a separate request is issued to select it's grandchildren. Changing the type of the Children property from ICollection to IQueryable doesn't solve this. Apart from missing needed methods like Add() and Remove(), EF just doesn't recognize the property then. Are there correct ways (as in: low database interaction) of querying through children (and what are they)? Or is this just not possible?

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  • Need help with simple NHibernate mapping...

    - by mplarsen
    Need help with a simple NHibernate relationship... Tables/Classes Request ------- RequestId Title … Keywords ------- RequestID (key) Keyword (key) Request mapping file <?xml version="1.0" encoding="utf-8" ?> <hibernate-mapping xmlns="urn:nhibernate-mapping-2.2" namespace="CR.Model" assembly="CR"> <class name="CR.Model.Request, CR table="[dbo].[Request]" lazy="true"> <id name="Id" column="[RequestID]"> <generator class="native" /> </id> <property name="RequestorID" column="[RequestorID]" /> <property name="RequestorOther" column="[RequestorOther]" /> … Keyword?? </class> </hibernate-mapping> How do I simply map multiple keywords to a request? I don't need another mapping file for the keyword class, do I? It's be great if I could not only get the associated keywords, but add them too...

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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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  • For a 1view/scene to 2view/scene app, what application should I choose in Xcode?

    - by Tony Xu
    The question may be simple to some others, but I have been struggling with this for a while. The app I want would be like this: first scene/view with two big buttons (no toolbar item), click each one to get into two new scenes. So totally three scenes. In Xcode, what application should I choose? And in storyboard how/should I drag/draw? Thanks. Update: thanks for the link, the big-number-user. I actually read that tutorial before I asked. A little update on what I got so far: 1, I selected "single view", so there's view controller 1 (VC1) in the storyboard. 2, dragged a navigation controller (NC), and move the initial view arrow pointing to NC 3, control-drag to link NC and VC1, selected "relationship segue root view controller" when some small dialog popup. IS THIS CORRECT? 4, created two additional VC, VC3 and VC4, control-drag link each to NC. selected "push", IS THIS CORRECT? 5, in VC1, I added two buttons, showVC3 and showVC4. NOW I DON'T KNOW how to add IBAction to button showVC3 and showVC4. I tried to control-drag it to ViewController.m file @interface and @end section, but failed. What should I do next?

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  • How to select "child" entities in subview?

    - by Andy
    I am trying to manage a drill-down list of data. I've got an entity, Contact, that has a to-many relationship with another entity, Rule. In my root view controller, I use a fetched results controller to manage and display the list of Contacts. When a Contact is tapped, I push a new view controller onto the stack with a list of the Contact's Rules. I have not been able to figure out how to use a second fetched results controller to display the Rules, so I'm using the following: // create a set of the contact's rules rules = [NSMutableSet set]; rules = [self.contact mutableSetValueForKey:@"rule"]; // create an array of rules from the set arrayOfRules = [NSMutableArray arrayWithCapacity:[rules count]]; for (id oneObject in rules) [arrayOfRules addObject:oneObject]; // sort the array of rules NSSortDescriptor *descriptor = [[NSSortDescriptor alloc] initWithKey:@"phoneLabel" ascending:YES]; [arrayOfRules sortUsingDescriptors:[NSArray arrayWithObject:descriptor]]; [descriptor release]; I create a set of Rules, then use that to create an array of Rules for sorting. I then use these two collections to populate the grouped table view. All of this appears to be working correctly. Here's my problem: There are several different actions a user can take in this view, and most of them require that I know which Rule was tapped. But I can't figure out how to get that. For instance, say a user wants to delete a Rule. It seems to me the proper approach is something like... [rules removeObject:ruleObjectToBeRemoved] ...but I can't figure out how to specifiy ruleObjectToBeRemoved. I hope all of this makes sense. As usual, thanks in advance for any advice you can offer.

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  • [Rails] Accessing error_messages on form_tag

    - by aaronrussell
    I have built a custom form for creating a joining model on a has_many :through relationship. The models look roughly like this: class Team has_many :team_members has_many :members, :through => :team_members end class Member has_many :team_members has_many :teams, :through => :team_members end class TeamMember belongs_to :team belongs_to :member # and this model has some validations too end The form I have built is for selecting which members should be in a team. I won't paste the form, but it uses the form_tag method and basically sends an array of hashes which contain a member_id and a squad_number. I then update the database with an action that looks roughly like this (simplified a bit, but you get the jist): @team.transaction do @team.team_members = params[:team_members].collect{|tm| @team.team_members.new(tm)} if @team.save redirect_to ... else render :action => :members end end Everything works great but I am validating the squad_number for uniqueness and numerically. So, when any of those validations fail, how do I get access to them in my view, and how do I ascertain which of the many members it has failed on?

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  • Retrieving Relationships from within two arrays of pointers

    - by DanF
    In a portion of a program I'm working on, I need to count all the times each person has worked on projects with each other person. Let's say we have "Employee" entities and "Session" entities. In each session, there are four project types, "A", "B", "C", & "D", each a many-to-many relationship to Employees. I'm making a loop to systematically review every person a selected person has worked with. First, I put all their project types in a single array, so it's easier to loop through, but by the time I ask the last nested Project for its Employee members, I get an "unrecognized selector" error. IBOutlet NSArrayController * list; int x; for(x = 0; x < [list count]; x++){ NSArray *A = [[list objectAtIndex:x] valueForKey:@"projectAs"]; NSArray *A = [[list objectAtIndex:x] valueForKey:@"projectBs"]; NSArray *A = [[list objectAtIndex:x] valueForKey:@"projectCs"]; NSArray *A = [[list objectAtIndex:x] valueForKey:@"projectDs"]; NSArray *masterList = [[NSArray alloc] initWithObjects: projectAs, projectBs, projectCs, projectDs, nil]; int y; for(y = 0; y < [masterList count]; y++){ int z; for(z = 0; z < [[masterlist objectAtIndex:y] count]; z++){ //And now to make an Array of this employee's partners on the selected object, to run comparisons on. //I also have an array of keys for each session's teams, so that's what I'm referencing here: NSArray * thisTeam = [list objectAtIndex:y] objectAtIndex:z] valueForKey:projectKey]; This throws an exception... namely, -[_NSFaultingMutableSet objectAtIndex:]: unrecognized selector sent to instance What's wrong with that last Array creation?

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  • Conceptual data modeling: Is RDF the right tool? Other solutions?

    - by paprika
    I'm planning a system that combines various data sources and lets users do simple queries on these. A part of the system needs to act as an abstraction layer that knows all connected data sources: the user shouldn't [need to] know about the underlying data "providers". A data provider could be anything: a relational DBMS, a bug tracking system, ..., a weather station. They are hooked up to the query system through a common API that defines how to "offer" data. The type of queries a certain data provider understands is given by its "offer" (e.g. I know these entities, I can give you aggregates of type X for relationship Y, ...). My concern right now is the unification of the data: the various data providers need to agree on a common vocabulary (e.g. the name of the entity "customer" could vary across different systems). Thus, defining a high level representation of the entities and their relationships is required. So far I have the following requirements: I need to be able to define objects and their properties/attributes. Further, arbitrary relations between these objects need to be represented: a verb that defines the nature of the relation (e.g. "knows"), the multiplicity (e.g. 1:n) and the direction/navigability of the relation. It occurs to me that RDF is a viable option, but is it "the right tool" for this job? What other solutions/frameworks do exist for semantic data modeling that have a machine readable representation and why are they better suited for this task? I'm grateful for every opinion and pointer to helpful resources.

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  • How to map this class in NHibernate (not FluentNHibernate)?

    - by JMSA
    Suppose I have a database like this: This is set up to give role-wise menu permissions. Please note that, User-table has no direct relationship with Permission-table. Then how should I map this class against the database-tables? class User { public int ID { get; set; } public string Name { get; set; } public string Username { get; set; } public string Password { get; set; } public bool? IsActive { get; set; } public IList<Role> RoleItems { get; set; } public IList<Permission> PermissionItems { get; set; } public IList<string> MenuItemKeys { get; set; } } This means, (1) Every user has some Roles. (2) Every user has some Permissions (depending on to Roles). (3) Every user has some permitted MenuItemKeys (according to Permissions). How should my User.hbm.xml look like?

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