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• Best Persistence choice for J2EE-App with frequently changing Data Model

  - by Ben-G

  Whenever I develop a J2EE-Application, I at some point decide to switch from my dummy Persistence (Simply Using Lists and other Data Structures) to some Sort of Database Persistence. Mostly when I hope the Data Model is more or less complete. From this point on, changes to the data model become exhausting, but unluckily they occur rather often. I've used different Object-Relational-Mappers (iBatis, Hibernate) for my projects. They definitely reduce the pain coming with Data Model changes, but they anyway let me adjust code/configuration at 3 or 4 places for every single change. To me, that's cumbersome and error prone. I made a better experience with DB4O, which simply persists Java Objects as they are, but I believe it's performance does not scale for huge applications. Is there anyway to maintain performance while letting out all the ugly configuration work? I'm seeking a performant framework which really hides persistence from my code. Wish for thinking? Or am I missing out THE technology? Hope you can help.

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• Organising data access for dependency injection

  - by IanAWP

  In our company we have a relatively long history of database backed applications, but have only just begun experimenting with dependency injection. I am looking for advice about how to convert our existing data access pattern into one more suited for dependency injection. Some specific questions: Do you create one access object per table (Given that a table represents an entity collection)? One interface per table? All of these would need the low level Data Access object to be injected, right? What about if there are dozens of tables, wouldn't that make the composition root into a nightmare? Would you instead have a single interface that defines things like GetCustomer(), GetOrder(), etc? If I took the example of EntityFramework, then I would have one Container that exposes an object for each table, but that container doesn't conform to any interface itself, so doesn't seem like it's compatible with DI. What we do now, in case it helps: The way we normally manage data access is through a generic data layer which exposes CRUD/Transaction capabilities and has provider specific subclasses which handle the creation of IDbConnection, IDbCommand, etc. Actual table access uses Table classes that perform the CRUD operations associated with a particular table and accept/return domain objects that the rest of the system deals with. These table classes expose only static methods, and utilise a static DataAccess singleton instantiated from a config file.

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• The Oracle MDM Portfolio & Strategy Session - It All Comes Down to Master Data

  - by Mala Narasimharajan

   By Narayana Machiraju We are less than a week now from the start of Oracle Open World 2012 and I would like to introduce you all to one of the most awaited MDM strategy sessions this year titled “What’s there to Know about Oracle’s Master Data Management Portfolio and Roadmap?”. Manouj Tahiliani, Senior Director of MDM Product Strategy provides you a complete picture of the Oracle MDM Portfolio, the Product releases, the Strategy and the Roadmaps. Manoj will be discussing Oracle Fusion MDM applications, the first enterprise-grade SaaS MDM product suite. You’ll hear strategies for leveraging MDM and data quality in the enterprise and how you can derive business value by deploying an MDM foundation for strategic initiatives such as customer experience management, product innovation, and financial transformation. And as a bonus, he is also going to discuss the confluence of MDM with emerging technologies such as big data, social, and mobile. The session is co-presented by GEHC and Westpac. Tony Craddock from Westpac is going to share the insights of their MDM Implementation in the lines of Business drivers, data governance, ROI and other important implementation considerations. A reprsentative from GEHC is going to talk about their MDM journey and the multi-domain MDM story. I strongly recommend yo not miss this important session The MDM track at Oracle Open World covers variety of topics related to MDM. In addition to the product management team presenting product updates and roadmap, we have several Customer Panels, Conference sessions and Customer round table sessions featuring a lot of marquee Customers. You can see an overview of MDM sessions here. 

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• Sorting a Grid of Data in ASP.NET MVC

  Last week's article, Displaying a Grid of Data in ASP.NET MVC, showed, step-by-step, how to display a grid of data in an ASP.NET MVC application. Last week's article started with creating a new ASP.NET MVC application in Visual Studio, then added the Northwind database to the project and showed how to use Microsoft's Linq-to-SQL tool to access data from the database. The article then looked at creating a Controller and View for displaying a list of product information (the Model). This article builds on the demo application created in Displaying a Grid of Data in ASP.NET MVC, enhancing the grid to include bi-directional sorting. If you come from an ASP.NET WebForms background, you know that the GridView control makes implementing sorting as easy as ticking a checkbox. Unfortunately, implementing sorting in ASP.NET MVC involves a bit more work than simply checking a checkbox, but the quantity of work isn't significantly greater and with ASP.NET MVC we have more control over the grid and sorting interface's layout and markup, as well as the mechanism through which sorting is implemented. With the GridView control, sorting is handled through form postbacks with the sorting parameters - what column to sort by and whether to sort in ascending or descending order - being submitted as hidden form fields. In this article we'll use querystring parameters to indicate the sorting parameters, which means a particular sort order can be indexed by search engines, bookmarked, emailed to a colleague, and so on - things that are not possible with the GridView's built-in sorting capabilities. Like with its predecessor, this article offers step-by-step instructions and includes a complete, working demo available for download at the end of the article. Read on to learn more! Read More >

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• SQLAuthority News – Download Whitepaper – Power View Infrastructure Configuration and Installation: Step-by-Step and Scripts

  - by pinaldave

  Power View, a feature of SQL Server 2012 Reporting Services Add-in for Microsoft SharePoint Server 2010 Enterprise Edition, is an interactive data exploration, visualization, and presentation experience. It provides intuitive ad-hoc reporting for business users such as data analysts, business decision makers, and information workers. Microsoft has recently released very interesting whitepaper which covers a sample scenario that validates the connectivity of the Power View reports to both PowerPivot workbooks and tabular models. This white paper talks about following important concepts about Power View: Understanding the hardware and software requirements and their download locations Installing and configuring the required infrastructure when Power View and its data models are on the same computer and on different computer Installing and configuring a computer used for client access to Power View reports, models, Sharepoint 2012 and Power View in a workgroup Configuring single sign-on access for double-hop scenarios with and without Kerberos You can download the whitepaper from here. This whitepaper talks about many interesting scenarios. It would be really interesting to know if you are using Power View in your production environment. If yes, would you please share your experience over here. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Business Intelligence, Data Warehousing, PostADay, SQL, SQL Authority, SQL Download, SQL Query, SQL Server, SQL Tips and Tricks, SQL White Papers, T SQL, Technology

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• Data Pump: Consistent Export?

  - by Mike Dietrich

  Ouch ... I have to admit as I did say in several workshops in the past weeks that a data pump export with expdp is per se consistent. Well ... I thought it is ... but it's not. Thanks to a customer who is doing a large unicode migration at the moment. We were discussing parameters in the expdp's par file. And I did ask my colleagues after doing some research on MOS. And here are the results of my "research": MOS Note 377218.1 has a nice example showing a data pump export of a partitioned table with DELETEs on that table as inconsistent Background:Back in the old 9i days when Data Pump was designed flashback technology wasn't as popular and well known as today - and UNDO usage was the major concern as a consistent per default export would have heavily relied on UNDO. That's why - similar to good ol' exp - the export won't operate per default in consistency mode To get a consistent data pump export with expdp you'll have to set: FLASHBACK_TIME=SYSTIMESTAMPin your parameter file. Then it will be consistent according to the timestamp when the process has been started. You could use FLASHBACK_SCN instead and determine the SCN beforehand if you'd like to be exact. So sorry if I had proclaimed a feature which unfortunately is not there by default - Mike

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• Flashback Data Archives: Ein gutes Gedächtnis für DBA und Entwickler

  - by Heinz-Wilhelm Fabry (DBA Community)

  Daten werden gespeichert und zum Teil lange aufbewahrt. Mitunter werden Daten nach ihrer ersten Speicherung geändert, vielleicht sogar mehrfach. Je nach gesetzlicher oder betrieblicher Vorgabe müssen die Veränderungen sogar nachverfolgbar sein. Damit sind zugleich Mechanismen gefordert, die sicherstellen, dass die Folge der Versionen lückenlos ist. Und implizit bedeutet das zusätzlich, dass die Versionen auch vor Löschen und Verändern geschützt sein müssen. Das Versionieren kann über die Anwendung, mit der die Daten auch erfasst werden, erfolgen, über Trigger oder über besondere Werkzeuge. Jede dieser Lösungen hat ihre eigenen Schwächen. Zusätzlich steht die Frage nach dem Schutz vor unerlaubtem Löschen oder Ändern versionierter Daten im Raum. Flashback Data Archives lösen diese Frage, denn sie bieten nicht nur einen wirksamen Mechanismus zum Versionieren von Datensätzen, sondern sie schützen diese Versionen auch vor Veränderung und löschen sie schließlich sogar automatisch nach Ablauf ihrer Aufbewahrungsfrist.Ursprünglich wurden die Archive als eigenständige Option zur Enterprise Edition der Oracle Database 11g unter dem Namen Total Recall eingeführt. Ende Juni 2012 verloren die Flashback Data Archives ihren Status als eigenständige Option. Weil die Archive aber grundsätzlich komprimiert wurden, hat Oracle sie stattdessen zu einem Feature der Advanced Compression Option der Enterprise Edition (ACO) gemacht. Seit der Version 11.2.0.4 der Datenbank ist das Komprimieren aber für die Archive nicht mehr zwangsläufig, sondern optional. Damit gibt es lizenzrechtlich erneut eine Änderung: Wer die Kompression verwendet, der muss nach wie vor ACO lizensieren. Wer die Flashback Data Archives dagegen ohne Kompression verwendet - also zum Beispiel Entwickler -, dem stehen sie ab 11.2.0.4 aufwärts im Lieferumfang aller Editionen der Datenbank zur Verfügung. Diese Änderung ist in den Handbüchern zur Lizensierung der Versionen 11.2 und 12.1 der Datenbank dokumentiert. Im Rahmen der DBA Community ist bereits über die Flashback Data Archives berichtet worden. Der hier vorliegende Artikel ersetzt alle vorangegangenen Beiträge zum Thema.

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• Updating an ADF Web Service Data Control When Service Structure or Location Change

  - by Shay Shmeltzer

  The web service data control in Oracle ADF gives you a simplified approach to consuming services in ADF applications, and now with ADF Mobile the usage of this service seems to be growing. A frequent question we get is what happens if the service that I'm consuming changes - how do I update my data control? Well, first we should mention that if you do a good design of your application before you actually code - then things like Web service method signature shouldn't change. The signature is the contract between the publisher and the consumer, and contracts shouldn't be broken. But in reality things do change during development stages, so here is how you can update both method signatures and service location with the Web service data control: After watching this video you might be tempted to not copy the WSDLs to your project - which lets you use the right click update on a data control. However there is a reason why the copy is on by default, it reduces network traffic when you are actually running your application since ADF doesn't need to go to the server to find out the service structure. So for runtime performance, you probably should keep the WSDL local.  I encourage you to further look into both the connections.xml file where your service location is saved, and the datacontrols.dcx file where its definition is kept to get an even deeper understanding of how ADF works underneath the declarative layers.

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• Hack a Linksys Router into a Ambient Data Monitor

  - by Jason Fitzpatrick

  If you have a data source (like a weather report, bus schedule, or other changing data set) you can pull it and display it with an ambient data monitor; this fun build combines a hacked Linksys router and a modified toy bus to display transit arrival times. John Graham-Cumming wanted to keep an eye on the current bus arrival time tables without constantly visiting the web site to check them. His workaround turns a hacked Linksys router, a display, a modified London city bus (you could hack apart a more project-specific enclosure, of course), and a simple bit code that polls the bus schedule’s API, into a cool ambient data monitor that displays the arrival time, in minutes, of the next two buses that will pass by his stop. The whole thing could easily be adapted to another API to display anything from stock prices to weather temps. Hit up the link below for more information on the project. Ambient Bus Arrival Monitor Hacked from Linksys Router [via Make] Make Your Own Windows 8 Start Button with Zero Memory Usage Reader Request: How To Repair Blurry Photos HTG Explains: What Can You Find in an Email Header?

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• Data indexing frameworks fit for large E-Commerce applications

  - by Dabu

  we wrote and still maintain a large E-Commerce application. Our feature list resembles what you would expect from most shops. We'd like to improve some of our features, and now the search/suggestion list functionality (enter some letters, a JScripted suggestion list appears) has caught our eye. Currently, we use http://xapian.org/. It has some drawbacks. Firstly, it's not actually the right solution. It has been created to index documents, not ever-changing data in a granularity that an E-Commerce application would need. Secondly, the load on the database is significant when we reindex all data every night. We'd like a framework that has been designed for indexing database data, which can add to the index easily and without much load, which can supply data changes in the backoffice quickly to the frontend without much load and delay. I'm aware of the fact that Xapian is Open Source and even Free Software, so we could adapt it to our needs if we decided to invest the time and manpower. But taking a quick look around for a solution more suited seems fair, right? Oh, and commercial applications are fine, too. FOSS is not required. Thanks a bunch.

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• Compressing 2D level data

  - by Lucius

  So, I'm developing a 2D, tile based game and a map maker thingy - all in Java. The problem is that recently I've been having some memory issues when about 4 maps are loaded. Each one of these maps are composed of 128x128 tiles and have 4 layers (for details and stuff). I already spent a good amount of time searching for solutions and the best thing I found was run-length enconding (RLE). It seems easy enough to use with static data, but is there a way to use it with data that is constantly changing, without a big drop in performance? In my maps, supposing I'm compressing the columns, I would have 128 rows, each with some amount of data (hopefully less than it would be without RLE). Whenever I change a tile, that whole row would have to be checked and I'm affraid that would slow down too much the production (and I'm in a somewhat tight schedule). Well, worst case scenario I work on each map individually, and save them using RLE, but it would be really nice if I could avoind that. EDIT: What I'm currently using to store the data for the tiles is a 2D array of HashMaps that use the layer as key and store the id of the tile in that position - like this: private HashMap< Integer, Integer [][]

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• Non use of persisted data – Part deux

  - by Dave Ballantyne

  In my last blog I showed how persisted data may not be used if you have used the base data on an include on an index. That wasn't the only problem ive had that showed the same symptom.  Using the same code as before,  I was executing similar to the below : select BillToAddressID,SOD.SalesOrderDetailID,SOH.CleanedGuid from sales.salesorderheader SOH join Sales.SalesOrderDetail SOD on SOH.SalesOrderID = SOD.SalesOrderID But,  due to a distribution error in statistics i found it necessary to use a table hint.  In this case, I wanted to force a loop join select BillToAddressID,SOD.SalesOrderDetailID,SOH.CleanedGuid from sales.salesorderheader SOH inner loop join Sales.SalesOrderDetail SOD on SOH.SalesOrderID = SOD.SalesOrderID   But, being the diligent  TSQL developer that I am ,looking at the execution plan I noticed that the ‘compute scalar’ operator was again calling the function.  Again,  profiler is a more graphic way to view this…..   All very odd,  just because ive forced a join , that has NOTHING, to do with my persisted data then something is causing the data to be re-evaluated. Not sure if there is any easy fix you can do to the TSQL here, but again its a lesson learned (or rather reinforced) examine the execution plan of every query you write to ensure that it is operating as you thought it would.

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• Displaying a Grid of Data in ASP.NET MVC

  One of the most common tasks we face as a web developers is displaying data in a grid. In its simplest incarnation, a grid merely displays information about a set of records - the orders placed by a particular customer, perhaps; however, most grids offer features like sorting, paging, and filtering to present the data in a more useful and readable manner. In ASP.NET WebForms the GridView control offers a quick and easy way to display a set of records in a grid, and offers features like sorting, paging, editing, and deleting with just a little extra work. On page load, the GridView automatically renders as an HTML <table> element, freeing you from having to write any markup and letting you focus instead on retrieving and binding the data to display to the GridView. In an ASP.NET MVC application, however, developers are on the hook for generating the markup rendered by each view. This task can be a bit daunting for developers new to ASP.NET MVC, especially those who have a background in WebForms. This is the first in a series of articles that explore how to display grids in an ASP.NET MVC application. This installment starts with a walk through of creating the ASP.NET MVC application and data access code used throughout this series. Next, it shows how to display a set of records in a simple grid. Future installments examine how to create richer grids that include sorting, paging, filtering, and client-side enhancements. We'll also look at pre-built grid solutions, like the Grid component in the MvcContrib project and JavaScript-based grids like jqGrid. But first things first - let's create an ASP.NET MVC application and see how to display database records in a web page. Read on to learn more! Read More >

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• Generate a Word document from list data

  - by PeterBrunone

  This came up on a discussion list lately, so I threw together some code to meet the need.  In short, a colleague needed to take the results of an InfoPath form survey and give them to the user in Word format.  The form data was already in a list item, so it was a simple matter of using the SharePoint API to get the list item, formatting the data appropriately, and using response headers to make the client machine treat the response as MS Word content.  The following rudimentary code can be run in an ASPX (or an assembly) in the 12 hive.  When you link to the page, send the list name and item ID in the querystring and use them to grab the appropriate data. // Clear the current response headers and set them up to look like a word doc.HttpContext.Current.Response.Clear();HttpContext.Current.Response.Charset ="";HttpContext.Current.Response.ContentType ="application/msword";string strFileName = "ThatWordFileYouWanted"+ ".doc";HttpContext.Current.Response.AddHeader("Content-Disposition", "inline;filename=" + strFileName);// Using the current site, get the List by name and then the Item by ID (from the URL).string myListName = HttpContext.Current.Request.Querystring["listName"];int myID = Convert.ToInt32(HttpContext.Current.Request.Querystring["itemID"]);SPSite oSite = SPContext.Current.Site;SPWeb oWeb = oSite.OpenWeb();SPList oList = oWeb.Lists["MyListName"];SPListItem oListItem = oList.Items.GetItemById(myID);// Build a string with the data -- format it with HTML if you like. StringBuilder strHTMLContent = newStringBuilder();// *// Here's where you pull individual fields out of the list item.// *// Once everything is ready, spit it out to the client machine.HttpContext.Current.Response.Write(strHTMLContent);HttpContext.Current.Response.End();HttpContext.Current.Response.Flush();

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• PASS Summit Preconference and Sessions

  - by Davide Mauri

  I’m very pleased to announce that I’ll be delivering a Pre-Conference at PASS Summit 2012. I’ll speak about Business Intelligence again (as I did in 2010) but this time I’ll focus only on Data Warehouse, since it’s big topic even alone. I’ll discuss not only what is a Data Warehouse, how it can be modeled and built, but also how it’s development can be approached using and Agile approach, bringing the experience I gathered in this field. Building the Agile Data Warehouse with SQL Server 2012 http://www.sqlpass.org/summit/2012/Sessions/SessionDetails.aspx?sid=2821 I’m sure you’ll like it, especially if you’re starting to create a BI Solution and you’re wondering what is a Data Warehouse, if it is still useful nowadays that everyone talks about Self-Service BI and In-Memory databases, and what’s the correct path to follow in order to have a successful project up and running. Beside this Preconference, I’ll also deliver a regular session, this time related to database administration, monitoring and tuning: DMVs: Power in Your Hands http://www.sqlpass.org/summit/2012/Sessions/SessionDetails.aspx?sid=3204 Here we’ll dive into the most useful DMVs, so that you’ll see how that can help in everyday management in order to discover, understand and optimze you SQL Server installation, from the server itself to the single query. See you there!!!!!

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• Keeping a domain model consistent with actual data

  - by fstuijt

  Recently domain driven design got my attention, and while thinking about how this approach could help us I came across the following problem. In DDD the common approach is to retrieve entities (or better, aggregate roots) from a repository which acts as a in-memory collection of these entities. After these entities have been retrieved, they can be updated or deleted by the user, however after retrieval they are essentially disconnected from the data source and one must actively inform the repository to update the data source and make is consistent again with our in-memory representation. What is the DDD approach to retrieving entities that should remain connected to the data source? For example, in our situation we retrieve a series of sensors that have a specific measurement during retrieval. Over time, these measurement values may change and our business logic in the domain model should respond to these changes properly. E.g., domain events may be raised if a sensor value exceeds a predefined threshold. However, using the repository approach, these sensor values are just snapshots, and are disconnected from the data source. Does any of you have an idea on how to solve this following the DDD approach?

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• PASS Summit Preconference and Sessions

  - by Davide Mauri

  I’m very pleased to announce that I’ll be delivering a Pre-Conference at PASS Summit 2012. I’ll speak about Business Intelligence again (as I did in 2010) but this time I’ll focus only on Data Warehouse, since it’s big topic even alone. I’ll discuss not only what is a Data Warehouse, how it can be modeled and built, but also how it’s development can be approached using and Agile approach, bringing the experience I gathered in this field. Building the Agile Data Warehouse with SQL Server 2012 http://www.sqlpass.org/summit/2012/Sessions/SessionDetails.aspx?sid=2821 I’m sure you’ll like it, especially if you’re starting to create a BI Solution and you’re wondering what is a Data Warehouse, if it is still useful nowadays that everyone talks about Self-Service BI and In-Memory databases, and what’s the correct path to follow in order to have a successful project up and running. Beside this Preconference, I’ll also deliver a regular session, this time related to database administration, monitoring and tuning: DMVs: Power in Your Hands http://www.sqlpass.org/summit/2012/Sessions/SessionDetails.aspx?sid=3204 Here we’ll dive into the most useful DMVs, so that you’ll see how that can help in everyday management in order to discover, understand and optimze you SQL Server installation, from the server itself to the single query. See you there!!!!!

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• How to determine if a .NET Type is a custom struct?

  - by SztupY

  Hi! How to write a simple method, that checks whether a concrete type is a custom struct (created with public struct { };) or not. Checking Type.IsValueType is not enough, because it is also true to int, long, etc, and adding a check to !IsPrimitiveType won't exclude decimal, DateTime and maybe some other value types. I know that most of the built in value types are actually "structs", but I only want to check for "custom structs" These questions are mostly the same but without the answer I need: #1 #2 #3

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• Design Patterns: What is a type

  - by contactmatt

  A very basic question, but after reading the "Design Patterns: Elements of reusable OO Software" book, I'm a little confused. The book states, "An object's type only refers to its interface-the set of request to which it can respond. An object can have many types, and objects of different classes can have the same type." Could someone please better explain what a Type is? I also don't understand how one object can have multiple types...unless the book is speaking of polymorphism....

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• Is it possible to read /write classes/structs written in c# from vb6

  - by Aftershock

  HI, I just wonder if that is possible. I know simple types can be read through com interface. Does anyone have experience with complex types as structs and classes?

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• How can data not stored in a DB be accessed from any activity in Android?

  - by jul

  hi, I'm passing data to a ListView to display some restaurant names. Now when clicking on an item I'd like to start another activity to display more restaurant data. I'm not sure about how to do it. Shall I pass all the restaurant data in a bundle through the intent object? Or shall I just pass the restaurant id and get the data in the other activity? In that case, how can I access my restaurantList from the other activity? In any case, how can I get data from the restaurant I clicked on (the view only contains the name)? Any help, pointers welcome! Thanks Jul ListView lv= (ListView)findViewById(R.id.listview); lv.setAdapter( new ArrayAdapter<String>(this,android.R.layout.simple_list_item_1,restaurantList.getRestaurantNames())); lv.setOnItemClickListener(new OnItemClickListener() { public void onItemClick(AdapterView<?> parent, View view, int position, long id) { Intent i = new Intent(Atable.this, RestaurantEdit.class); Bundle b = new Bundle(); //b.putInt("id", ? ); startActivityForResult(i, ACTIVITY_EDIT); } }); RestaurantList.java package org.digitalfarm.atable; import java.util.ArrayList; import java.util.List; public class RestaurantList { private List<Restaurant> restaurants = new ArrayList<Restaurant>(); public List<Restaurant> getRestaurants() { return this.restaurants; } public void setRestaurants(List<Restaurant> restaurants) { this.restaurants = restaurants; } public List<String> getRestaurantNames() { List<String> restaurantNames = new ArrayList<String>(); for (int i=0; i<this.restaurants.size(); i++) { restaurantNames.add(this.restaurants.get(i).getName()); } return restaurantNames; } } Restaurant.java package org.digitalfarm.atable; public class Restaurant { private int id; private String name; private float latitude; private float longitude; public int getId() { return this.id; } public void setId(int id) { this.id = id; } public String getName() { return this.name; } public void setName(String name) { this.name = name; } public float getLatitude() { return this.latitude; } public void setLatitude(float latitude) { this.latitude = latitude; } public float getLongitude() { return this.longitude; } public void setLongitude(float longitude) { this.longitude = longitude; } }

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• Suppress Null Value Types from Being Emitted by XmlSerializer

  - by Ben Griswold

  Please consider the following Amount value type property which is marked as a nullable XmlElement: [XmlElement(IsNullable=true)] public double? Amount { get ; set ; } When a nullable value type is set to null, the C# XmlSerializer result looks like the following: <amount xsi:nil="true" /> Rather than emitting this element, I would like the XmlSerializer to suppress the element completely. Why? We're using Authorize.NET for online payments and Authorize.NET rejects the request if this null element exists. The current solution/workaround is to not serialize the Amount value type property at all. Instead we have created a complementary property, SerializableAmount, which is based on Amount and is serialized instead. Since SerializableAmount is of type String, which like reference types are suppressed by the XmlSerializer if null by default, everything works great. /// <summary> /// Gets or sets the amount. /// </summary> [XmlIgnore] public double? Amount { get; set; } /// <summary> /// Gets or sets the amount for serialization purposes only. /// This had to be done because setting value types to null /// does not prevent them from being included when a class /// is being serialized. When a nullable value type is set /// to null, such as with the Amount property, the result /// looks like: &gt;amount xsi:nil="true" /&lt; which will /// cause the Authorize.NET to reject the request. Strings /// when set to null will be removed as they are a /// reference type. /// </summary> [XmlElement("amount", IsNullable = false)] public string SerializableAmount { get { return this.Amount == null ? null : this.Amount.ToString(); } set { this.Amount = Convert.ToDouble(value); } } Of course, this is just a workaround. Is there a cleaner way to suppress null value type elements from being emitted?

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• Getting types of the attributes in an ActiveRecord object

  - by Michael Neale

  I would like to know if it is possible to get the types (as known by AR - eg in the migration script and database) programmatically (I know the data exists in there somewhere). For example, I can deal with all the attribute names: ar.attribute_names.each { |name| puts name } .attributes just returns a mapping of the names to their current values (eg no type info if the field isn't set). Some places I have seen it with the type information: in script/console, type the name of an AR entity: >> Driver => Driver(id: integer, name: string, created_at: datetime, updated_at: datetime) So clearly it knows the types. Also, there is .column_for_attribute, which takes an attr name and returns a column object - which has the type buried in the underlying database column object, but it doesn't appear to be a clean way to get it. I would also be interested in if there is a way that is friendly for the new "ActiveModel" that is coming (rails3) and is decoupled from database specifics (but perhaps type info will not be part of it, I can't seem to find out if it is). Thanks.

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• QFileDialog filter from mime-types

  - by Mathias

  I want the filter in a QFileDialog to match all audio file types supported by Phonon on the platform in question. 1 - However I am not able to find a way in Qt to use mime types in a filter. How can I do that? 2 - Or how can I find the corresponding file extensions for the mimetypes manually? The solution should be Qt based, or at least be cross platform and supported everywhere Qt is. Following is a short code describing my problem: #include <QApplication> #include <QFileDialog> #include <QStringList> #include <phonon/backendcapabilities.h> QString mime_to_ext(QString mime) { // WHAT TO REALLY DO ?? // NEEDLESS TO SAY; THIS IS WRONG... return mime.split("/").back().split('-').back(); } int main(int argc, char **argv) { QApplication app(argc, argv); QStringList p_audio_exts; QStringList p_mime_types = Phonon::BackendCapabilities::availableMimeTypes(); for(QStringList::iterator i = p_mime_types.begin(), ie = p_mime_types.end(); i != ie; i++) { if((*i).startsWith("audio")) p_audio_exts << mime_to_ext(*i); } QString filter = QString("All Files(*)"); if(!p_audio_exts.isEmpty()) { QString p_audio_filter = QString("Audio Files (*.%1)").arg(p_audio_exts.join(" *.")); filter = QString("%1;;%2").arg(p_audio_filter).arg(filter); } QFileDialog dialog(NULL, "Open Audio File", QString::null, filter); dialog.exec(); }

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• What are best practices for collecting, maintaining and ensuring accuracy of a huge data set?

  - by Kyle West

  I am posing this question looking for practical advice on how to design a system. Sites like amazon.com and pandora have and maintain huge data sets to run their core business. For example, amazon (and every other major e-commerce site) has millions of products for sale, images of those products, pricing, specifications, etc. etc. etc. Ignoring the data coming in from 3rd party sellers and the user generated content all that "stuff" had to come from somewhere and is maintained by someone. It's also incredibly detailed and accurate. How? How do they do it? Is there just an army of data-entry clerks or have they devised systems to handle the grunt work? My company is in a similar situation. We maintain a huge (10-of-millions of records) catalog of automotive parts and the cars they fit. We've been at it for a while now and have come up with a number of programs and processes to keep our catalog growing and accurate; however, it seems like to grow the catalog to x items we need to grow the team to y. I need to figure some ways to increase the efficiency of the data team and hopefully I can learn from the work of others. Any suggestions are appreciated, more though would be links to content I could spend some serious time reading. THANKS! Kyle

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