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  • Why is it bad to use boolean flags in databases? And what should be used instead?

    - by David Chanin
    I've been reading through some of guides on database optimization and best practices and a lot of them suggest not using boolean flags at all in the DB schema (ex http://forge.mysql.com/wiki/Top10SQLPerformanceTips). However, they never provide any reason as to why this is bad. Is it a peformance issue? is it hard to index or query properly? Furthermore, if boolean flags are bad, what should you use to store boolean values in a database? Is it better to store boolean flags as an integer and use a bitmask? This seems like it would be less readable.

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  • iPhone: Core Data save Class object

    - by Nic Hubbard
    I have an entity in core data called Location. Inside this I have a few fields, such as date. But, I would also like to save a class object in it that I created called Annotation. What type of attribute would I use for this, since it is a custom class object that I created? Location (object) |__ Date |__ Annotation (MKAnnotation protocol)

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  • In Rails, how can a record belong_to a single user, but also have multiple "secondary" users?

    - by Kuro
    In my app, I have a User model and a Project model. A user has_many assignments and each project belongs_to a user. But along with each project having an owner, the user who created it, I would like the owner be able to share it with others (so that the project gets shown on the other users' account along with their own). I imagine having to use has_many :through, and setting up a projects_users table with a user_id and a project_id. And I guess this would be the end result? Project.first.user # The creator of the project => #<User id: 1, name: 'andrew', etc...> Project.first.users # The users that the creator chose to share it with => [#<User id: 2 ...>, #<User id: 3 ...>] How would I go about doing this? Thanks!

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  • IE event callback object JavaScript

    - by Randy Hall
    I may be WAY off on my terminology, so please feel free to correct me. Perhaps this is why I cannot seem to find anything relevant. No libraries, please. I have an event handler, which invokes a callback function. Fancy, right? In IE<9 the this object in the handler is the window. I don't know why, or how to access the correct object. if (document.addEventListener){ element.addEventListener(event, callback, false); } else { element.attachEvent('on' +event, callback); } This part DOES WORK. This part doesn't: function callback(event){ console.log(this); } this in IE is returning [object Window], whereas it returns the element that called the callback function in every other browser. This is cut down significantly from my full script, but this should be everything that's relevant. EDIT This link provided by @metadings How to reference the caller object ("this") using attachEvent is very close. However, there are still two issues. 1) I need to get both the event object and the DOM element calling this function. 2) This event is handled delegation style: there may be child DOM elements firing the event, meaning event.target is not necessarily (and in my case, not typically) the element with the listener.

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  • Put an object in Handler message

    - by Tsimmi
    Hi! I need to download an image from the internet, in a different thread, and then send that image object in the handler message, to the UI thread. I already have this: ... Message msg = Message.obtain(); Bundle b = new Bundle(); b.putParcelable("MyObject", (Parcelable) object); msg.setData(b); handler.sendMessage(msg); And when I receive this message, I want to extract the object: ... public void handleMessage(Message msg) { super.handleMessage(msg); MyObject objectRcvd = (MyObject) msg.getData().getParcelable("IpTile"); addToCache(ipTile); mapView.invalidate(); } But this is giving me: ...java.lang.ClassCastException... Can anyone help? And by the way, is this the most efficient way to pass an object to the UI Thread? Thank you all!

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  • index 'enabled' fields good idea?

    - by sibidiba
    Content of a website is stored in a MySQL database. 99% of the content will be enabled, but some (users, posts etc.) will be disabled. Most of the queries end as WHERE (...) AND enabled Is it a good idea to create an index on the field 'enabled'?

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  • How do I left join tables in unidirectional many-to-one in Hibernate?

    - by jbarz
    I'm piggy-backing off of http://stackoverflow.com/questions/2368195/how-to-join-tables-in-unidirectional-many-to-one-condition. If you have two classes: class A { @Id public Long id; } class B { @Id public Long id; @ManyToOne @JoinColumn(name = "parent_id", referencedColumnName = "id") public A parent; } B - A is a many to one relationship. I understand that I could add a Collection of Bs to A however I do not want that association. So my actual question is, Is there an HQL or Criteria way of creating the SQL query: select * from A left join B on (b.parent_id = a.id) This will retrieve all A records with a Cartesian product of each B record that references A and will include A records that have no B referencing them. If you use: from A a, B b where b.a = a then it is an inner join and you do not receive the A records that do not have a B referencing them. I have not found a good way of doing this without two queries so anything less than that would be great. Thanks.

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  • Javascript new object (function ) vs inline invocation

    - by Sheldon Ross
    Is there any considerations to determine which is better practice for creating an object with private members? var object = new function () { var private = "private variable"; return { method : function () { ..dosomething with private; } } } VS var object = function () { ... }(); Basically what is the difference between using NEW here, and just invoking the function immediately after we define it?

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  • Using a c# .net object in an Excel VBA form

    - by Mark O'G
    Hi I have a .net object that I want to use in Excel. I have an existing VBA script that i need to alter to call this the object from. I have then converted the object to a TLB. I've not really touched on this area before so any help will be appreciated. I have created an interface [Guid("0F700B48-E0CA-446b-B87E-555BCC317D74"),InterfaceType(ComInterfaceType.InterfaceIsDual)] public interface IOfficeCOMInterface { [DispId(1)] void ResetOrder(); [DispId(2)] void SetDeliveryAddress(string PostalName, string AddressLine1, string AddressLine2, string AddressLine3, string AddressLine4, string PostCode, string CountryCode, string TelephoneNo, string FaxNo, string EmailAddress); } I have also created an class that inherits that object. [ClassInterface(ClassInterfaceType.None), ProgId("NAMESPACE.OfficeCOMInterface"), Guid("9D9723F9-8CF1-4834-BE69-C3FEAAAAB530"), ComVisible(true)] public class OfficeCOMInterface : IOfficeCOMInterface, IDisposable { public void ResetSOPOrder() { } public void SetDeliveryAddress(string PostalName, string AddressLine1, string AddressLine2, string AddressLine3, string AddressLine4, string PostCode, string CountryCode, string TelephoneNo, string FaxNo, string EmailAddress) { try { SalesOrder.AmendDeliveryAddress(PostalName, AddressLine1, AddressLine2, AddressLine3, AddressLine4, PostCode); MessageBox.Show("Delivery address set"); } catch (Exception ex) { throw ex; } } }

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  • populate textarea from model arraylist

    - by user281180
    I have an arraylist namelist in my model and in my view I need to fill the textarea with the values in the arraylist {%> <%=Html.TextArea("Namelist",Html.Encode(namelist))%> <%} But i`m having the following in my textarea being dislpayed: System.Collections.ArrayList... How to solve this?

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  • determining name of object loaded in R

    - by andrewj
    Imagine you have an object foo that you saved as saved.file.rda as follows: foo <- 'a' save(foo, file='saved.file.rda') Suppose you load saved.file.rda into an environment with multiple objects but forgot the name of the object that is in saved.file.rda. Is there a way in R to determine that name? You can do it the following way, which seems a little clunky: bar <- load('saved.file.rda') eval(parse(text=bar)) # this will pull up the object that was in saved.file.rda However, is there a better way of doing this?

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  • object.jquery attribute

    - by Esteve Camps
    Hello, what does this code performs? if(object.jquery){ .... } I don't know what jQuery attribute does. I think it checks if 'object' is a valid jQuery object, but I'm not really sure. Thanks in advance. Esteve

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  • Facebook Open Graph Not Showing Object Title

    - by gregavola
    I'm having conflicting reports for our users that people that share Object Graph objects to their wall, are sometimes showing the Object title and other times not. Specifically, every test I do on my own account shows the Object Title, but on their Mobile apps - it doesn't appear. I've tested the Open Graph debugger.So I have a couple of questions: Is there a length limit on the number of characters? Does Facebook not show the whole Object.title on Mobile? Does Facebook scrap the OG tags and if it can't find them or if it timeout do they not receive them? Here is my sample OG url: https://untappd.com/user/gregavola/checkin/35486976 Response from FB: Post on my Wall: What can I do here? What am I missing?

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  • Object serialization practical uses?

    - by nash
    How many software projects have you worked on used object serialization? I personally never came across a scenario where object serialization was used. One use case i can think of is, a server software storing objects to disk to save memory. Are there other types of software where object serialization is essential or preferred over a database?

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  • Killing COM object from C#

    - by Pradeep
    I have a COM object that we are calling from C#. This works great, and I have my own pool of objects that I can use whenever I want. Now I need to kill the object. I've tried releasing the COM object explicitly and then garbage collecting from another thread, but that does nothing. Does anyone have any other ideas to kill this object? Thanks for the help. I've tried System.Runtime.InteropServices.Marshal.ReleaseComObject(myApp); GC.Collect(); GC.WaitForPendingFinalizers (); myApp = null; and I create it by myApplication.ApplicationClass myApp = new myApplication.ApplicationClass(); Thanks, Pradeep

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  • A table that has relation to itself issue

    - by Mostafa
    Hi , I've defined table with this schema : CREATE TABLE [dbo].[Codings]( [Id] [int] IDENTITY(1,1) NOT NULL, [ParentId] [int] NULL, [CodeId] [int] NOT NULL, [Title] [nvarchar](50) COLLATE Arabic_CI_AI NOT NULL, CONSTRAINT [PK_Codings] PRIMARY KEY CLUSTERED ( [Id] ASC )WITH (IGNORE_DUP_KEY = OFF) ON [PRIMARY] ) ON [PRIMARY] And fill it up with data like this : Id ParentId CodeId Title ----------- ----------- ----------- ---------- 1 NULL 0 Gender 2 1 1 Male 3 1 2 Female 4 NULL 0 Educational Level 5 4 1 BS 6 4 2 MS 7 4 3 PHD Now , I'm looking for a solution , in order , When i delete a record that is parent ( like Id= 1 or 4 ), It delete all child automatically ( all records that their ParentId is 1 or 4 ) . I supposed i can do it via relation between Id and Parent Id ( and set cascade for delete rule ) , But when i do that in MMS , the Delete Rule or Update Rule in Properties is disabled . My question is , What can i do to accomplish this ? Thank you

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  • OCL constraints intended prevent node creation in an GMF generated editor only makes it invisible

    - by TheMorph
    Hello, I am working on editors created with GMF and struggling with OCL right now. Is there a possibilty to prevent a node to be created if an OCL statement in the mapping evaluates to false? If tried adding an OCL statement to a node and all it does is making the node not visible in the editor, but it is created. There is also an OCL statement in the ecore file, but this way it is only evaluated when there should be something done with the created model. I does not prevent a user to construct an invalid model but this is what I intend to prevent. Thanks in advance, Morph

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  • JAVA - Strange problem (probably thread problem) with JTable & Model

    - by Stefanos Kargas
    I am using 2 Tables (JTable) with their DefaultTableModels. The first table is already populated. The second table is populated for each row of the first table (using an SQL Query). My purpose is to export every line of the first table with it's respective lines of the second in an Excel File. I am doing it with a for (for each line of 1st table), in which I write a line of the 1st table in the Excel File, then I populate the 2nd table (for this line of 1st Table), I get every line from the Table (from it's Model actually) and put it in the Excel File under the current line of 1st table. This means that if I have n lines in first table I will clear and populate again the second table n times. All this code is called in a seperate thread. THE PROBLEM IS: Everything works perfectly fine ecxept that I am getting some exceptions. The strange thing is that I'm not getting anything false in my result. The Excel file is perfect. Some of the lines of the exceptions are: Exception in thread "AWT-EventQueue-0" java.lang.ArrayIndexOutOfBoundsException: 0 = 0 at java.util.Vector.elementAt(Vector.java:427) at javax.swing.table.DefaultTableModel.getValueAt(DefaultTableModel.java:632) at javax.swing.JComponent.paint(JComponent.java:1017) at javax.swing.RepaintManager.paint(RepaintManager.java:1220) at javax.swing.RepaintManager.paintDirtyRegions(RepaintManager.java:803) I am assuming that the problem lies in the fact that the second table needs some more time to be populated before I try to get any data from it. That's why I see RepaintManager and paintDirtyRegions in my exceptions. Another thing I did is that I ran my program in debug mode and I put a breakpoint after each population of the 2nd table. Then I pressed F5 to continue for each population of 2nd table and no exception appeared. The program came to it's end without any exceptions. This is another important fact that tells me that maybe in this case I gave the table enough time to be populated. Of course you will ask me: If your program works fine, why do you care about the exceptions? I care for avoiding any future problems and I care to have a better understanding of Java and Java GUI and threads. Why do you depend on a GUI component (and it's model) to get your information and why don't you recreate the resultset that populates your tables using an SQL Query and get your info from the resultset? That would be the best and the right way. The fact is that I have the tables code ready and it was easier for me to just get the info from them. But the right way would be to get everything direct from database. Anyway what I did brought out my question, and answering it would help me understand more things about java. So I posted it.

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  • Immutability of big objects

    - by Malax
    Hi StackOverflow! I have some big (more than 3 fields) Objects which can and should be immutable. Every time I run into that case i tend to create constructor abominations with long parameter lists. It doesn't feel right, is hard to use and readability suffers. It is even worse if the fields are some sort of collection type like lists. A simple addSibling(S s) would ease the object creation so much but renders the object mutable. What do you guys use in such cases? I'm on Scala and Java, but i think the problem is language agnostic as long as the language is object oriented. Solutions I can think of: "Constructor abominations with long parameter lists" The Builder Pattern Thanks for your input!

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  • window.setInterval from inside an object

    - by Keith Rousseau
    I'm currently having an issue where I have a javascript object that is trying to use setInterval to call a private function inside of itself. However, it can't find the object when I try to call it. I have a feeling that it's because window.setInterval is trying to call into the object from outside but doesn't have a reference to the object. FWIW - I can't get it to work with the function being public either. The basic requirement is that I may need to have multiple instances of this object to track multiple uploads that are occurring at once. If you have a better design than the current one or can get the current one working then I'm all ears. The following code is meant to continuously ping a web service to get the status of my file upload: var FileUploader = function(uploadKey) { var intervalId; var UpdateProgress = function() { $.get('someWebService', {}, function(json) { alert('success'); }); }; return { BeginTrackProgress: function() { intervalId = window.setInterval('UpdateProgress()', 1500); }, EndTrackProgress: function() { clearInterval(intervalId); } }; }; This is how it is being called: var fileUploader = new FileUploader('myFileKey'); fileUploader.BeginTrackProgress();

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