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  • How to do an additional search on archive in rails if record not found, by extending model?

    - by Nick Gorbikoff
    Hello, I was wondering if somebody knows an elegant solution to the following: Suppose I have a table that holds orders, with a bunch of data. So I'm at 1M records, and searches begin to take time. So I want to speed it up by archiving some data that is more than 3 years old - saving it into a table called orders-archive, and then purging them from the orders table. So if we need to research something or customer wants to pull older information - they still can, but 99% of the lookups are done on the orders no older than a year and a half - so there is no reason to keep looking through older data all the time. These move & purge operations can be then croned to be done on a weekly basis. I already did some tests and I know that I will slash my search times by about 4 times. So far so good, right? However I was thinking about how to implement older archival lookups and the only reasonable thing I can think of is some sort of if-else If not found in orders, do a search in orders-archive. However - I have about 20 tables that I want to archive and god knows how many searches / finds are done through out the code, that I don't want to modify. So I was wondering if there is an elegant rails-way solution to this problem, by extending a model somehow? Has anyone dealt with similar case before? Thank you.

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  • What do you call a generalized (non-GUI-related) "Model-View-Controller" architecture?

    - by dcuccia
    I am currently refactoring code that coordinates multiple hardware components for data acquisition, and feeling a bit like I'm recreating the wheel. In particular, an MVC-like pattern seems to be emerging. Except, this has nothing to do with a GUI and I'm worried that I'm forcing this particular pattern where another might be more appropriate. Here's my scenario: Individual hardware "component" classes obey interface contracts for each hardware type. Previously, component instances were orchestrated by a single monolithic InstrumentController class, which relied heavily on configuration + branching logic for executing a specific acquisition sequence. After an iteration, I have a separate controller for each component, with these controllers all managed by a small InstrumentControllerBase (or its derivatives). The composite system will receive "input" either programmatically or via inter-hardware component triggering - in either case these interactions are routed to, and handled by, the appropriate controller. So, I have something that feels MVC-esque, but I don't know if that's because I'm forcing the point. With little direct MVC experience in application development, it's hard to know if I'm just trying to make my scenario fit MVC, where another pattern might be a good alternative or complimentary. My problem is, search results and wiki documentation of these family of patterns seems to immediately drop me into GUI-specific discussions. I understand "M means Model data and the V means View" - but do you call the superset pattern? Component-Commander-Controller? Whence can I exhume examples exemplary?

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  • Data Modeling: Logical Modeling Exercise

    - by swisscheese
    In trying to learn the art of data storage I have been trying to take in as much solid information as possible. PerformanceDBA posted some really helpful tutorials/examples in the following posts among others: is my data normalized? and Relational table naming convention. I already asked a subset question of this model here. So to make sure I understood the concepts he presented and I have seen elsewhere I wanted to take things a step or two further and see if I am grasping the concepts. Hence the purpose of this post, which hopefully others can also learn from. Everything I present is conceptual to me and for learning rather than applying it in some production system. It would be cool to get some input from PerformanceDBA also since I used his models to get started, but I appreciate all input given from anyone. As I am new to databases and especially modeling I will be the first to admit that I may not always ask the right questions, explain my thoughts clearly, or use the right verbage due to lack of expertise on the subject. So please keep that in mind and feel free to steer me in the right direction if I head off track. If there is enough interest in this I would like to take this from the logical to physical phases to show the evolution of the process and share it here on Stack. I will keep this thread for the Logical Diagram though and start new one for the additional steps. For my understanding I will be building a MySQL DB in the end to run some tests and see if what I came up with actually works. Here is the list of things that I want to capture in this conceptual model. Edit for V1.2 The purpose of this is to list Bands, their members, and the Events that they will be appearing at, as well as offer music and other merchandise for sale Members will be able to match up with friends Members can write reviews on the Bands, their music, and their events. There can only be one review per member on a given item, although they can edit their reviews and history will be maintained. BandMembers will have the chance to write a single Comment on Reviews about the Band they are associated with. Collectively as a Band only one Comment is allowed per Review. Members can then rate all Reviews and Comments but only once per given instance Members can select their favorite Bands, music, Merchandise, and Events Bands, Songs, and Events will be categorized into the type of Genre that they are and then further subcategorized into a SubGenre if necessary. It is ok for a Band or Event to fall into more then one Genre/SubGenre combination. Event date, time, and location will be posted for a given band and members can show that they will be attending the Event. An Event can be comprised of more than one Band, and multiple Events can take place at a single location on the same day Every party will be tied to at least one address and address history shall be maintained. Each party could also be tied to more then one address at a time (i.e. billing, shipping, physical) There will be stored profiles for Bands, BandMembers, and general members. So there it is, maybe a bit involved but could be a great learning tool for many hopefully as the process evolves and input is given by the community. Any input? EDIT v1.1 In response to PerformanceDBA U.3) That means no merchandise other than Band merchandise in the database. Correct ? That was my original thought but you got me thinking. Maybe the site would want to sell its own merchandise or even other merchandise from the bands. Not sure a mod to make for that. Would it require an entire rework of the Catalog section or just the identifying relationship that exists with the Band? Attempted a mod to sell both complete albums or song. Either way they would both be in electronic format only available for download. That is why I listed an Album as being comprised of Songs rather then 2 separate entities. U.5) I understand what you bring up about the circular relation with Favorite. I would like to get to this “It is either one Entity with some form of differentiation (FavoriteType) which identifies its treatment” but how to is not clear to me. What am I missing here? u.6) “Business Rules This is probably the only area you are weak in.” Thanks for the honest response. I will readdress these but I hope to clear up some confusion in my head first with the responses I have posted back to you. Q.1) Yes I would like to have Accepted, Rejected, and Blocked. I am not sure what you are referring to as to how this would change the logical model? Q.2) A person does not have to be a User. They can exist only as a BandMember. Is that what you are asking? Minor Issue Zero, One, or More…Oops I admit I forgot to give this attention when building the model. I am submitting this version as is and will address in a future version. I need to read up more on Constraint Checking to make sure I am understanding things. M.4) Depends if you envision OrderPurchase in the future. Can you expand as to what you mean here? EDIT V1.2 In response to PerformanceDBA input... Lessons learned. I was mixing the concept of Identifying / Non-Identifying and Cardinality (i.e. Genre / SubGenre), and doing so inconsistently to make things worse. Associative Tables are not required in Logical Diagrams as their many-to-many relationships can be depicted and then expanded in the Physical Model. I was overlooking the Cardinality in a lot of the relationships The importance of reading through relationships using effective Verb Phrases to reassure I am modeling what I want to accomplish. U.2) In the concept of this model it is only required to track a Venue as a location for an Event. No further data needs to be collected. With that being said Events will take place on a given EventDate and will be hosted at a Venue. Venues will host multiple events and possibly multiple events on a given date. In my new model my thinking was that EventDate is already tied to Event . Therefore, Venue will not need a relationship with EventDate. The 5th and 6th bullets you have listed under U.2) leave me questioning my thinking though. Am I missing something here? U.3) Is it time to move the link between Item and Band up to Item and Party instead? With the current design I don't see a possibility to sell merchandise not tied to the band as you have brought up. U.5) I left as per your input rather than making it a discrete Supertype/Subtype Relationship as I don’t see a benefit of having that type of roll up. Additional Revisions AR.1) After going through the exercise for FavoriteItem, I feel that Item to Review requires a many-to-many relationship so that is indicated. Necessary? Ok here we go for v1.3 I took a few days on this version, going back and forth with my design. Once the logical process is complete, as I want to see if I am on the right track, I will go through in depth what I had learned and the troubles I faced as a beginner going through this process. The big point for this version was it took throwing in some Keys to help see what I was missing in the past. Going through the process of doing a matrix proved to be of great help also. Regardless of anything, if it wasn't for the input given by PerformanceDBA I would still be a lost soul wondering in the dark. Who knows my current design might reaffirm that I still am, but I have learned a lot so I am know I at least have a flashlight in my hand. At this point in time I admit that I am still confused about identifying and non-identifying relationships. In my model I had to use non-identifying relationships with non nulls just to join the relationships I wanted to model. In reading a lot on the subject there seems to be a lot of disagreement and indecisiveness on the subject so I did what I thought represented the right things in my model. When to force (identifying) and when to be free (non-identifying)? Anyone have inputs? EDIT V1.4 Ok took the V1.3 inputs and cleaned things up for this V1.4 Currently working on a V1.5 to include attributes.

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  • Simple Remote Shared Object with Red5 Flash Server

    - by John Russell
    Hello, I am trying to create a simple chat client using the red5 media server, but I seem to be having a slight hiccup. I am creating a shared object on the server side, and it seems to be creating it successfully. However, when I make changes to the object via the client (type a message), the SYNC event fires, but the content within the shared object remains empty. I suspect I am doing something wrong on the java end, any advice? Console Results: Success! Server Message: clear Server Message: [object Object] Local message: asdf Server Message: change Server Message: [object Object] Local message: fdsa Server Message: change Server Message: [object Object] Local message: fewa Server Message: change Server Message: [object Object] Server Side: package org.red5.core; import java.util.List; import org.red5.server.adapter.ApplicationAdapter; import org.red5.server.api.IConnection; import org.red5.server.api.IScope; import org.red5.server.api.service.ServiceUtils; import org.red5.server.api.so.ISharedObject; // import org.apache.commons.logging.Log; // import org.apache.commons.logging.LogFactory; public class Application extends ApplicationAdapter { private IScope appScope; // private static final Log log = LogFactory.getLog( Application.class ); /** {@inheritDoc} */ @Override public boolean connect(IConnection conn, IScope scope, Object[] params) { appScope = scope; createSharedObject(appScope, "generalChat", false); // Creates general chat shared object return true; } /** {@inheritDoc} */ @Override public void disconnect(IConnection conn, IScope scope) { super.disconnect(conn, scope); } public void updateChat(Object[] params) { ISharedObject so = getSharedObject(appScope, "generalChat"); // Declares and stores general chat data in general chat shared object so.setAttribute("point", params[0].toString()); } } Client Side: package { import flash.display.MovieClip; import flash.events.*; import flash.net.*; // This class is going to handle all data to and from from media server public class SOConnect extends MovieClip { // Variables var nc:NetConnection = null; var so:SharedObject; public function SOConnect():void { } public function connect():void { // Create a NetConnection and connect to red5 nc = new NetConnection(); nc.addEventListener(NetStatusEvent.NET_STATUS, netStatusHandler); nc.connect("rtmp://localhost/testChat"); // Create a StoredObject for general chat so = SharedObject.getRemote("generalChat", nc.uri, false); so.connect(nc); so.addEventListener(SyncEvent.SYNC, receiveChat) } public function sendChat(msg:String) { trace ("Local message: " + msg); nc.call("updateChat", null, msg) } public function receiveChat(e:SyncEvent):void { for (var i in e.changeList) { trace ("Server Message: " + e.changeList[i].code) trace ("Server Message: " + e.changeList[i]) } } // Given result, determine successful connection private function netStatusHandler(e:NetStatusEvent):void { if (e.info.code == "NetConnection.Connect.Success") { trace("Success!"); } else { trace("Failure!\n"); trace(e.info.code); } } } }

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  • integrating tinymce with asp .net MVC 4.0

    - by user1865670
    using ASP .NET MVC 4.0 , VS2012. In one of my page, I tried to integrate a WYSIWYG editor "TinyMCE". To integrate, I followed the following URL : .tugberkugurlu.com My view page is like : @model AboutModels @using FileUploadDemo.Models <script src="https://ajax.googleapis.com/ajax/libs/jquery/1.7.2/jquery.js"></script> <script src="https://ajax.googleapis.com/ajax/libs/jquery/1.7.2/jquery.min.js"></script> <script src="Scripts/tinymce/jquery.tinymce.js" type="text/javascript"></script> @{ ViewBag.Title = "About"; } @using (Html.BeginForm()) { @Html.ValidationSummary(true) <fieldset> <legend>About</legend> <div class="editor-label"> @Html.LabelFor(model => model.Title) </div> <div class="editor-field"> @Html.EditorFor(model => model.Title) @Html.ValidationMessageFor(model => model.Title) </div> <div class="editor-label"> @Html.LabelFor(model => model.PostedOn) </div> <div class="editor-field"> @Html.EditorFor(model => model.PostedOn) @Html.ValidationMessageFor(model => model.PostedOn) </div> <div class="editor-label"> @Html.LabelFor(model => model.Tags) </div> <div class="editor-field"> @Html.EditorFor(model => model.Tags) @Html.ValidationMessageFor(model => model.Tags) </div> <div class="editor-label"> @Html.LabelFor(model => model.Content) </div> <div class="editor-field"> @Html.EditorFor(model => model.Content) @Html.ValidationMessageFor(model => model.Content) </div> <p> <input type="submit" value="Create" /> </p> <p> Posted Content : @ViewBag.HtmlContent </p> </fieldset> } Here my Model is like : public class AboutModels { public string Title { get; set; } public DateTime PostedOn { get; set; } public string Tags { get; set; } [UIHint("tinymce_jquery_full"), AllowHtml] public string Content { get; set; } } My about page loads with all features. "@html.EditorFor(model=>model.content)" also loads fine. but no "WYSIWYG" pane(i donno what it is called, the pane is used to edit my text written in the textarea(HTml.editorFor())) is loaded. In the runtime, Exception is thrown in jquery.tinymce.js file. Error Message : `Unhandled exception at line 86, column 11 in http://localhost:1706/Home/About 0x800a01b6 - Microsoft JScript runtime error: Object doesn't support this property or method` And give me two options, Continue or Break . If i continue, the page loads with features as i mentioned earlier. If i Break, then it stays in the jquery.tinymce.js file with a yellow text-background. I have no experience with Javascript/jquery. And new in ASP .NET MVC 4.0, actually this is my first try of web application in .net. I updated jquery from nuGet. What could be the possible ways to solve it?

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  • Why is my WCF RIA Services custom object deserializing with an extra list member?

    - by oasasaurus
    I have been developing a Silverlight WCF RIA Services application dealing with mock financial transactions. To more efficiently send summary data to the client without going overboard with serialized entities I have created a summary class that isn’t in my EDM, and figured out how to serialize and send it over the wire to the SL client using DataContract() and DataMember(). Everything seemed to be working out great, until I tried to bind controls to a list inside my custom object. The list seems to always get deserialized with an extra, almost empty entity in it that I don’t know how to get rid of. So, here are some of the pieces. First the relevant bits from the custom object class: <DataContract()> _ Public Class EconomicsSummary Public Sub New() RecentTransactions = New List(Of Transaction) TotalAccountHistory = New List(Of Transaction) End Sub Public Sub New(ByVal enUser As EntityUser) Me.UserId = enUser.UserId Me.UserName = enUser.UserName Me.Accounts = enUser.Accounts Me.Jobs = enUser.Jobs RecentTransactions = New List(Of Transaction) TotalAccountHistory = New List(Of Transaction) End Sub <DataMember()> _ <Key()> _ Public Property UserId As System.Guid <DataMember()> _ Public Property NumTransactions As Integer <DataMember()> _ <Include()> _ <Association("Summary_RecentTransactions", "UserId", "User_UserId")> _ Public Property RecentTransactions As List(Of Transaction) <DataMember()> _ <Include()> _ <Association("Summary_TotalAccountHistory", "UserId", "User_UserId")> _ Public Property TotalAccountHistory As List(Of Transaction) End Class Next, the relevant parts of the function called to return the object: Public Function GetEconomicsSummary(ByVal guidUserId As System.Guid) As EconomicsSummary Dim objOutput As New EconomicsSummary(enUser) For Each objTransaction As Transaction In (From t As Transaction In Me.ObjectContext.Transactions.Include("Account") Where t.Account.aspnet_User_UserId = guidUserId Select t Order By t.TransactionDate Descending Take 10) objTransaction.User_UserId = objOutput.UserId objOutput.RecentTransactions.Add(objTransaction) Next objOutput.NumTransactions = objOutput.RecentTransactions.Count … Return objOutput End Function Notice that I’m collecting the NumTransactions count before serialization. Should be 10 right? It is – BEFORE serialization. The DataGrid is bound to the data source as follows: <sdk:DataGrid AutoGenerateColumns="False" Height="100" MaxWidth="{Binding ElementName=aciSummary, Path=ActualWidth}" ItemsSource="{Binding Source={StaticResource EconomicsSummaryRecentTransactionsViewSource}, Mode=OneWay}" Name="gridRecentTransactions" RowDetailsVisibilityMode="VisibleWhenSelected" IsReadOnly="True"> <sdk:DataGrid.Columns> <sdk:DataGridTextColumn x:Name="TransactionDateColumn" Binding="{Binding Path=TransactionDate, StringFormat=\{0:d\}}" Header="Date" Width="SizeToHeader" /> <sdk:DataGridTextColumn x:Name="AccountNameColumn" Binding="{Binding Path=Account.Title}" Header="Account" Width="SizeToCells" /> <sdk:DataGridTextColumn x:Name="CurrencyAmountColumn" Binding="{Binding Path=CurrencyAmount, StringFormat=\{0:c\}}" Header="Amount" Width="SizeToHeader" /> <sdk:DataGridTextColumn x:Name="TitleColumn" Binding="{Binding Path=Title}" Header="Description" Width="SizeToCells" /> <sdk:DataGridTextColumn x:Name="ItemQuantityColumn" Binding="{Binding Path=ItemQuantity}" Header="Qty" Width="SizeToHeader" /> </sdk:DataGrid.Columns> </sdk:DataGrid> You might be wondering where the ItemsSource is coming from, that looks like this: <CollectionViewSource x:Key="EconomicsSummaryRecentTransactionsViewSource" Source="{Binding Path=DataView.RecentTransactions, ElementName=EconomicsSummaryDomainDataSource}" /> When I noticed that the DataGrid had the extra row I tried outputting some data after the data source finishes loading, as follows: Private Sub EconomicsSummaryDomainDataSource_LoadedData(ByVal sender As System.Object, ByVal e As System.Windows.Controls.LoadedDataEventArgs) Handles EconomicsSummaryDomainDataSource.LoadedData If e.HasError Then System.Windows.MessageBox.Show(e.Error.ToString, "Load Error", System.Windows.MessageBoxButton.OK) e.MarkErrorAsHandled() End If Dim objSummary As EconomicsSummary = CType(EconomicsSummaryDomainDataSource.Data(0), EconomicsSummary) Dim sb As New StringBuilder("") sb.AppendLine(String.Format("Num Transactions: {0} ({1})", objSummary.RecentTransactions.Count.ToString(), objSummary.NumTransactions.ToString())) For Each objTransaction As Transaction In objSummary.RecentTransactions sb.AppendLine(String.Format("Recent TransactionId {0} dated {1} CurrencyAmount {2} NewBalance {3}", objTransaction.TransactionId.ToString, objTransaction.TransactionDate.ToString("d"), objTransaction.CurrencyAmount.ToString("c"), objTransaction.NewBalance.ToString("c"))) Next txtDebug.Text = sb.ToString() End Sub Output from that looks like this: Num Transactions: 11 (10) Recent TransactionId 2283 dated 6/1/2010 CurrencyAmount $31.00 NewBalance $392.00 Recent TransactionId 2281 dated 5/31/2010 CurrencyAmount $33.00 NewBalance $361.00 Recent TransactionId 2279 dated 5/28/2010 CurrencyAmount $8.00 NewBalance $328.00 Recent TransactionId 2277 dated 5/26/2010 CurrencyAmount $22.00 NewBalance $320.00 Recent TransactionId 2275 dated 5/24/2010 CurrencyAmount $5.00 NewBalance $298.00 Recent TransactionId 2273 dated 5/21/2010 CurrencyAmount $19.00 NewBalance $293.00 Recent TransactionId 2271 dated 5/20/2010 CurrencyAmount $20.00 NewBalance $274.00 Recent TransactionId 2269 dated 5/19/2010 CurrencyAmount $48.00 NewBalance $254.00 Recent TransactionId 2267 dated 5/18/2010 CurrencyAmount $42.00 NewBalance $206.00 Recent TransactionId 2265 dated 5/14/2010 CurrencyAmount $5.00 NewBalance $164.00 Recent TransactionId 0 dated 6/1/2010 CurrencyAmount $0.00 NewBalance $361.00 So I have a few different questions: -First and foremost, where the devil is that extra Transaction entity coming from and how do I get rid of it? Does it have anything to do with the other list of Transaction entities being serialized as part of the EconomicsSummary class (TotalAccountHistory)? Do I need to decorate the EconomicsSummary class members a little more/differently? -Second, where are the peculiar values coming from on that extra entity? PRE-POSTING UPDATE 1: I did a little checking, it looks like that last entry is the first one in the TotalAccountHistory list. Do I need to do something with CollectionDataContract()? PRE-POSTING UPDATE 2: I fixed one bug in TotalAccountHistory, since the objects weren’t coming from the database their keys weren’t unique. So I set the keys on the Transaction entities inside TotalAccountHistory to be unique and guess what? Now, after deserialization RecentTransactions contains all its original items, plus every item in TotalAccountHistory. I’m pretty sure this has to do with the deserializer getting confused by two collections of the same type. But I don’t yet know how to resolve it…

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  • MySQL Relational Database Foreign Key

    - by user623879
    To learn databasing, I am creating a movie database. To associate multiple directors with a movie, I have the following schema: movie(m_ID, ....) m_director(dirID, dirName)//dirID is a autoincrement primary key m_directs(dirID, m_ID) //dirID, m_ID are set as foreign Keys in the mysql database(InnoDB engine) I have a program that connects to the db that needs to add a movie to the database. I can easily add a new entry to the movie table and the m_director table, but I am having trouble adding a entry in the m_directs table. INSERT INTO m_director (dirName) VALUES("Jason Reitman"); INSERT INTO m_directs (dirID, m_ID) VALUES(LAST_INSERT_ID(), "tt0467406"); I am using this sql statement to insert a new director and add the association to the movie. I know the primary key of the movie, but I don't know the dirID, so I use LAST_INSERT_ID() to get the last id of the director just inserted. The problem I am having is that I get the following error: MySql.Data.MySqlClient.MySqlException (0x80004005): Cannot add or update a child row: a foreign key constraint fails (`siteproducts`. `m_directs`, CONSTRAINT `m_directs_ibfk_2` FOREIGN KEY (`dirID`) REFERENCES `m_directs` (`dirID`) ON DELETE CASCADE ON UPDATE CASCADE) Any ideas?

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  • Pros/Cons of document based database vs relational database

    - by damian
    I've been trying to see if I can accomplish some requirements with a document based database, in this case CouchDB. Two generic requirements: CRUD of entities with some fields which have unique index on it ecommerce web app like eBay (better description here). And I'm begining to think that a Document-based database isn't the best choice to address these requirements. Furthermore, I can´t imagine a use for a Document based database (maybe my imagination is too little). Can you explain me if I am asking pears to an elm when I try to use a Document based database for this requirements?

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  • Example of an ASP.NET MVC post model?

    - by Anthony Potts
    I was watching the HaHaa presentation on ASP.NET MVC from MIX and they mentioned using a Post Model where I guess they were saying you could use a model that was ONLY for posting. I have tried looking for examples for this. Am I not understanding what they are saying? Does anyone have an example of how this might work in a strongly typed view where the view model and post model are not of the same type?

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  • Django User model, adding function

    - by Hellnar
    Hello, I want to add a new function to the default User model of Django for retrieveing a related list of Model type. Such Foo model: class Foo(models.Model): owner = models.ForeignKey(User, related_name="owner") likes = models.ForeignKey(User, related_name="likes") ........ #at some view user = request.user foos= user.get_related_foo_models() Hwo can this be achieved ?

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  • relational database: how to design this table

    - by donpal
    I'm a database newbie designing a database. I'll use SO to ask my question because it's easier to ask it on something that you can see already, but it's not the same, it will just help me understand the right approach. As you can see, there are many questions here and each can have many answers. How should I store the answers in a table? Should I store all the answers in the SAME table with a unique id (make it the key) and just a new field for the question id? What if there are 100,000 answers like there is here? Do I still store them in 1 table? What keys should I use to minimize search time when I want to search for the answers of a specific question? The database is both read and write if that makes any difference in this case.

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  • WPF - 'Relational' Data in XAML Using DataContext

    - by Andy T
    Hi, Say I have a list of Employee IDs from one data source and a separate data source with a list of Employees, with their ID, Surname, FirstName, etc. Is it possible in XAML only to get the Employee's name from the second data source and display it next to the ID, using something like this (with the syntax corrected)?.. <TextBlock x:Name="EmployeeID" Text="{Binding ID}"></TextBlock> <TextBlock Grid.Column="1" DataContext="{StaticResource EmployeeList[**where ID = {Binding ID}**]}" Text="{Binding Surname}"/> I'm thinking back to my days using XML and XSLT with XPath to achieve the kind of thing shown above. Is this kind of thing possible in XAML? Or do I need to 'denormalize' the data first in code, into one consolidated list? It seems like it should be possible to do this simple task using XAML only, but I can't quite get my head around how you would switch the DataContext correctly and what the syntax would be to achieve this. Is it possible, or am I barking up the wrong tree? Thanks, AT

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  • Explanation of converting exporting an XML document as a relational database using XSLT

    - by Yaaqov
    I would like to better understand the basic steps needed to a take an XML document like this Breakfast Menu... <?xml version="1.0" encoding="ISO-8859-1"?> <breakfast_menu> <food> <name>Belgian Waffles</name> <price>$5.95</price> <description>two of our famous Belgian Waffles with plenty of real maple syrup</description> <calories>650</calories> </food> <food> <name>Strawberry Belgian Waffles</name> <price>$7.95</price> <description>light Belgian waffles covered with strawberries and whipped cream</description> <calories>900</calories> </food> <food> <name>Berry-Berry Belgian Waffles</name> <price>$8.95</price> <description>light Belgian waffles covered with an assortment of fresh berries and whipped cream</description> <calories>900</calories> </food> <food> <name>French Toast</name> <price>$4.50</price> <description>thick slices made from our homemade sourdough bread</description> <calories>600</calories> </food> <food> <name>Homestyle Breakfast</name> <price>$6.95</price> <description>two eggs, bacon or sausage, toast, and our ever-popular hash browns</description> <calories>950</calories> </food> </breakfast_menu> And "export" it to say, an Access or MySQL database using XSLT, creating two joined tables: Table: breakfast_menu Field: menu_item_id Field: food_id Table: food Field: food_id Field: name Field: price Field: description Field: calories If there are online tutorials on this that you know of, I'd be interesting in learning more, as well. Thanks.

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  • Options for keeping models and the UI in sync (in a desktop application context)

    - by Benju
    In my experience I have only had 2 patterns work for large-scale desktop application development when trying to keep the model and UI in sync. 1-An eventbus approach via a shared eventbus command objects are fired (ie:UserDemographicsUpdatedEvent) and have various parts of the UI update if they are bound to the same user object updated in this event. 2-Attempt to bind the UI directly to the model adding listeners to the model itself as needed. I find this approach rather clunky as it pollutes the domain model. Does anybody have other suggestions? In a web application with something like JSP binding to the model is easy as you ussually only care about the state of the model at the time your request comes in, not so in a desktop type application. Any ideas?

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  • NSNotification center may not respond to -object ?

    - by blackkettle
    Hi, I'm trying to make simple use of the NSNotification center inside my iPhone application, but I seem to be doing something wrong in this case. I was under the impression that it was possible to retrieve an object associated with a particular message, or at least a reference to the object, but using the following example code I'm getting a warning, "NSNotification center may not respond to -object" - (void)addNewBookmark:(NSNotificationCenter *)notification { Bookmark *newBookMark = (Bookmark *)[notification object]; //Do some stuff with the bookmark object } Indeed, when I compile and run the code, basically nothing I try to do with the contents of the object actually gets carried out - it's simply ignored. The post code is as follows, - (IBAction)save:(id) sender{ //Sending the message with the related object [[NSNotificationCenter defaultCenter] postNotificationName:@"addNewBookmark" object:bookmark]; } and the bookmark object itself is just a dictionary. I also tried using the "userInfo" argument and passing the bookmark object through that, but the result was the same. How should I be doing this? What am I doing wrong?

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  • C#: Inheritance, Overriding, and Hiding

    - by Rosarch
    I'm having difficulty with an architectural decision for my C# XNA game. The basic entity in the world, such as a tree, zombie, or the player, is represented as a GameObject. Each GameObject is composed of at least a GameObjectController, GameObjectModel, and GameObjectView. These three are enough for simple entities, like inanimate trees or rocks. However, as I try to keep the functionality as factored out as possible, the inheritance begins to feel unwieldy. Syntactically, I'm not even sure how best to accomplish my goals. Here is the GameObjectController: public class GameObjectController { protected GameObjectModel model; protected GameObjectView view; public GameObjectController(GameObjectManager gameObjectManager) { this.gameObjectManager = gameObjectManager; model = new GameObjectModel(this); view = new GameObjectView(this); } public GameObjectManager GameObjectManager { get { return gameObjectManager; } } public virtual GameObjectView View { get { return view; } } public virtual GameObjectModel Model { get { return model; } } public virtual void Update(long tick) { } } I want to specify that each subclass of GameObjectController will have accessible at least a GameObjectView and GameObjectModel. If subclasses are fine using those classes, but perhaps are overriding for a more sophisticated Update() method, I don't want them to have to duplicate the code to produce those dependencies. So, the GameObjectController constructor sets those objects up. However, some objects do want to override the model and view. This is where the trouble comes in. Some objects need to fight, so they are CombatantGameObjects: public class CombatantGameObject : GameObjectController { protected new readonly CombatantGameModel model; public new virtual CombatantGameModel Model { get { return model; } } protected readonly CombatEngine combatEngine; public CombatantGameObject(GameObjectManager gameObjectManager, CombatEngine combatEngine) : base(gameObjectManager) { model = new CombatantGameModel(this); this.combatEngine = combatEngine; } public override void Update(long tick) { if (model.Health <= 0) { gameObjectManager.RemoveFromWorld(this); } base.Update(tick); } } Still pretty simple. Is my use of new to hide instance variables correct? Note that I'm assigning CombatantObjectController.model here, even though GameObjectController.Model was already set. And, combatants don't need any special view functionality, so they leave GameObjectController.View alone. Then I get down to the PlayerController, at which a bug is found. public class PlayerController : CombatantGameObject { private readonly IInputReader inputReader; private new readonly PlayerModel model; public new PlayerModel Model { get { return model; } } private float lastInventoryIndexAt; private float lastThrowAt; public PlayerController(GameObjectManager gameObjectManager, IInputReader inputReader, CombatEngine combatEngine) : base(gameObjectManager, combatEngine) { this.inputReader = inputReader; model = new PlayerModel(this); Model.Health = Constants.PLAYER_HEALTH; } public override void Update(long tick) { if (Model.Health <= 0) { gameObjectManager.RemoveFromWorld(this); for (int i = 0; i < 10; i++) { Debug.WriteLine("YOU DEAD SON!!!"); } return; } UpdateFromInput(tick); // .... } } The first time that this line is executed, I get a null reference exception: model.Body.ApplyImpulse(movementImpulse, model.Position); model.Position looks at model.Body, which is null. This is a function that initializes GameObjects before they are deployed into the world: public void Initialize(GameObjectController controller, IDictionary<string, string> data, WorldState worldState) { controller.View.read(data); controller.View.createSpriteAnimations(data, _assets); controller.Model.read(data); SetUpPhysics(controller, worldState, controller.Model.BoundingCircleRadius, Single.Parse(data["x"]), Single.Parse(data["y"]), bool.Parse(data["isBullet"])); } Every object is passed as a GameObjectController. Does that mean that if the object is really a PlayerController, controller.Model will refer to the base's GameObjectModel and not the PlayerController's overriden PlayerObjectModel? In response to rh: This means that now for a PlayerModel p, p.Model is not equivalent to ((CombatantGameObject)p).Model, and also not equivalent to ((GameObjectController)p).Model. That is exactly what I do not want. I want: PlayerController p; p.Model == ((CombatantGameObject)p).Model p.Model == ((GameObjectController)p).Model How can I do this? override?

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  • Replace textfields with dropdown select fields

    - by 47
    I have three model classes that look as below: class Model(models.Model): model = models.CharField(max_length=20, blank=False) manufacturer = models.ForeignKey(Manufacturer) date_added = models.DateField(default=datetime.today) def __unicode__(self): name = ''+str(self.manufacturer)+" "+str(self.model) return name class Series(models.Model): series = models.CharField(max_length=20, blank=True, null=True) model = models.ForeignKey(Model) date_added = models.DateField(default=datetime.today) def __unicode__(self): name = str(self.model)+" "+str(self.series) return name class Manufacturer(models.Model): MANUFACTURER_POPULARITY_CHOICES = ( ('1', 'Primary'), ('2', 'Secondary'), ('3', 'Tertiary'), ) manufacturer = models.CharField(max_length=15, blank=False) date_added = models.DateField(default=datetime.today) manufacturer_popularity = models.CharField(max_length=1, choices=MANUFACTURER_POPULARITY_CHOICES) def __unicode__(self): return self.manufacturer I want to have the fields for model series and manufacturer represented as dropdowns instead of text fields. I have customized the model forms as below: class SeriesForm(ModelForm): series = forms.ModelChoiceField(queryset=Series.objects.all()) class Meta: model = Series exclude = ('model', 'date_added',) class ModelForm(ModelForm): model = forms.ModelChoiceField(queryset=Model.objects.all()) class Meta: model = Model exclude = ('manufacturer', 'date_added',) class ManufacturerForm(ModelForm): manufacturer = forms.ModelChoiceField(queryset=Manufacturer.objects.all()) class Meta: model = Manufacturer exclude = ('date_added',) However, the dropdowns are populated with the unicode in the respective class...how can I further customize this to get the end result I want? Also, how can I populate the forms with the correct data for editing? Currently only SeriesForm is populated. The starting point of all this is from another class whose declaration is as below: class CommonVehicle(models.Model): year = models.ForeignKey(Year) series = models.ForeignKey(Series) .... def __unicode__(self): name = ''+str(self.year)+" "+str(self.series) return name

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  • How do I know an array of structures was allocated in the Large Object Heap (LOH) in .NET?

    - by AMissico
    After some experimenation using CLR Profiler, I found that: Node[,] n = new Node[100,23]; //'84,028 bytes, is not placed in LOH Node[,] n = new Node[100,24]; //'86,428 bytes, is public struct Node { public int Value; public Point Point; public Color Color; public bool Handled; public Object Tag; } During run-time, how do I know an array of structures (or any array) was allocated in the Large Object Heap (LOH)?

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  • Usage of WCF RIA Services, where the datasource isn't a classical (relational) database

    - by Kottan
    I want (have) to write a Silverlight and (or) ASP.NET based webapplication with SAP in the backend (in other words, the datasource is no classical database) . The usage of Silverlight and ASP.NET is a precondition. Is it possible to use the WCF RIA Services (and Silverlight) where the data-source are RFCs from SAP ? Makes this sense ? If yes, how the pattern/architecture could be shortly described ? Or should I take other architectures into considerations (usage of plain WCF services, WCF data services,...) ?

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  • How do Relational Databases Work Under the Hood?

    - by Pierreten
    I've always been interested in how you can throw some SQL at at database, and it nearly instantaneously returns your results in an orderly manner without thinking about it as anything other than a black box. What is really going on? I'm pretty sure it has something to do with how values are laid out regularly in memory, similar to an array; but aside from that, I don't know much else. How is SQL parsed in a manner to facilitate all of this?

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  • Accessing a dictionary value by custom object value in Python?

    - by Sam
    So I have a square that's made up of a series of points. At every point there is a corresponding value. What I want to do is build a dictionary like this: class Point: def __init__(self, x, y): self._x = x self._y = y square = {} for x in range(0, 5): for y in range(0, 5): point = Point(x,y) square[point] = None However, if I later create a new point object and try to access the value of the dictionary with the key of that point it doesn't work.. square[Point(2,2)] Traceback (most recent call last): File "<pyshell#19>", line 1, in <module> square[Point(2,2)] KeyError: <__main__.Point instance at 0x02E6C378> I'm guessing that this is because python doesn't consider two objects with the same properties to be the same object? Is there any way around this? Thanks

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  • If you are forced to use an Anemic domain model, where do you put your business logic and calculated

    - by Jess
    Our current O/RM tool does not really allow for rich domain models, so we are forced to utilize anemic (DTO) entities everywhere. This has worked fine, but I continue to struggle with where to put basic object-based business logic and calculated fields. Current layers: Presentation Service Repository Data/Entity Our repository layer has most of the basic fetch/validate/save logic, although the service layer does a lot of the more complex validation & saving (since save operations also do logging, checking of permissions, etc). The problem is where to put code like this: Decimal CalculateTotal(LineItemEntity li) { return li.Quantity * li.Price; } or Decimal CalculateOrderTotal(OrderEntity order) { Decimal orderTotal = 0; foreach (LineItemEntity li in order.LineItems) { orderTotal += CalculateTotal(li); } return orderTotal; } Any thoughts?

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  • Add a record to relational XML with C#

    - by Megawolt
    I have a XML and XSD I want to add a record to trck table with Dataset i'm also write that code but need trackListrow... how can i handle that? playListDS rec = new playListDS(); if(File.Exists(Server.MapPath("~/playlist.xml"))) rec.ReadXml(Server.MapPath("~/playlist.xml")); int id = int.Parse(rec.track.Rows[rec.track.Rows.Count - 1][0].ToString()) + 1; if (ViewState["Filename"] != null && ViewState["Cover"] != null) { playListDS.trackListRow row = new playListDS.trackListRow(); rec.track.AddtrackRow(id.ToString(), "mp3/" + ViewState["Filename"].ToString(), txtartist.Text, txtalbum.Text, txttitle.Text, txtannotation.Text, txtduration.Text, "mp3/cover" + ViewState["Cover"].ToString(), txtinfo.Text, txtlink.Text); <?xml version="1.0"?> <!-- Generated using Flame-Ware Solutions XML-2-XSD v2.0 at http://www.flame-ware.com/Products/XML-2-XSD/ --> <xs:schema id="playListDS" targetNamespace="http://tempuri.org/playListDS.xsd" xmlns:mstns="http://tempuri.org/playListDS.xsd" xmlns="http://tempuri.org/playListDS.xsd" xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns:msdata="urn:schemas-microsoft-com:xml-msdata" attributeFormDefault="qualified" elementFormDefault="qualified"> <xs:element name="playListDS" msdata:IsDataSet="true" msdata:UseCurrentLocale="true"> <xs:complexType> <xs:choice minOccurs="0" maxOccurs="1"> <xs:element name="trackList"> <xs:complexType> <xs:sequence> <xs:element name="track" minOccurs="0" maxOccurs="unbounded"> <xs:complexType> <xs:sequence> <xs:element name="FileID" type="xs:string" minOccurs="0" /> <xs:element name="location" type="xs:string" minOccurs="0" /> <xs:element name="creator" type="xs:string" minOccurs="0" /> <xs:element name="album" type="xs:string" minOccurs="0" /> <xs:element name="title" type="xs:string" minOccurs="0" /> <xs:element name="annotation" type="xs:string" minOccurs="0" /> <xs:element name="duration" type="xs:string" minOccurs="0" /> <xs:element name="image" type="xs:string" minOccurs="0" /> <xs:element name="info" type="xs:string" minOccurs="0" /> <xs:element name="link" type="xs:string" minOccurs="0" /> </xs:sequence> </xs:complexType> </xs:element> </xs:sequence> </xs:complexType> </xs:element> </xs:choice> </xs:complexType> </xs:element> </xs:schema> <?xml version="1.0" standalone="yes"?> <playListDS xmlns="http://tempuri.org/playListDS.xsd"> <trackList> <track> <FileID>6</FileID> <location>mp3/Gomez - See The World-1.mp3</location> <creator>Gomez</creator> <album>How We Operate</album> <title>See the World</title> <annotation>Buraya kendi yorumun gelicek bos kalabilir</annotation> <duration>243670</duration> <image>mp3/coverChrysanthemum.jpg</image> <info /> <link>Grubun bi sitesi fln varsa buraya yazabilisin yoksa beni sil</link> </track> </trackList> </playListDS>

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  • Event sourcing: Write event before or after updating the model

    - by Magnus
    I'm reasoning about event sourcing and often I arrive at a chicken and egg problem. Would be grateful for some hints on how to reason around this. If I execute all I/O-bound processing async (ie writing to the event log) then how do I handle, or sometimes even detect, failures? I'm using Akka Actors so processing is sequential for each event/message. I do not have any database at this time, instead I would persist all the events in an event log and then keep an aggregated state of all the events in a model stored in memory. Queries are all against this model, you can consider it to be a cache. Example Creating a new user: Validate that the user does not exist in model Persist event to journal Update model (in memory) If step 3 breaks I still have persisted my event so I can replay it at a later date. If step 2 breaks I can handle that as well gracefully. This is fine, but since step 2 is I/O-bound I figured that I should do I/O in a separate actor to free up the first actor for queries: Updating a user while allowing queries (A0 = Front end/GUI actor, A1 = Processor Actor, A2 = IO-actor, E = event bus). (A0-E-A1) Event is published to update user 'U1'. Validate that the user 'U1' exists in model (A1-A2) Persist event to journal (separate actor) (A0-E-A1-A0) Query for user 'U1' profile (A2-A1) Event is now persisted continue to update model (A0-E-A1-A0) Query for user 'U1' profile (now returns fresh data) This is appealing since queries can be processed while I/O-is churning along at it's own pace. But now I can cause myself all kinds of problems where I could have two incompatible commands (delete and then update) be persisted to the event log and crash on me when replayed up at a later date, since I do the validation before persisting the event and then update the model. My aim is to have a simple reasoning around my model (since Actor processes messages sequentially single threaded) but not be waiting for I/O-bound updates when Querying. I get the feeling I'm modeling a database which in itself is might be a problem. If things are unclear please write a comment.

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  • What is the best solution to do Reporting on Object data for .NET ?

    - by Peter Fox
    Hi, Our projects are using objects as the data source to reports. Our business layer is returning single objects or IEnumerable. Our reports (quite complex) need to display value-type properties of the object, and its related objects. Typical case would be, from a List, display a master report with category data, then a subreport with data for each Product inside each Category, then a subreport for each Part of each Product, and so on. Reporting from the database is not an option for us. We have tried so far - Reporting Services : works but have to mess around with the XML definition of the report to define the datasource classes, very hard to work with if you use an object datasource, architecturally not too clean - Telerik Reports : quite nice (esp., nice architecture) but seems to have problems with complex reports (master/sub), does not give great paging control, rumored to have performance/crash problems (immature product). Does anyone know a good reporting solution that can be integrated in an ASP.NET application and works well with objects as datasources ?

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