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  • How to Overcome or fix MIXED_DML_OPERATION error in Salesforce APEX without future method ?

    - by sathya
    How to Overcome or fix MIXED_DML_OPERATION error in Salesforce APEX without future method ?MIXED_DML_OPERATION :-one of the worst issues we have ever faced :)While trying to perform DML operation on a setup object and non-setup object in a single action you will face this error.Following are the solutions I tried and the final one worked out :-1. perform the 1st objects DML on normal apex method. Then Call the 2nd objects DML through a future method.    Drawback :- You cant get a response from the future method as its context is different and because its executing asynchronously and that its static.2. Tried the following option but it didnt work :-    1. perform the dml operation on the normal apex method.    2. tried calling the 2nd dml from trigger thinking that it would be in a different context. But it didnt work.    3. Some suggestions were given in some blogs that we could try System.runas()   Unfortunately that works only for test class.   4. Finally achieved it with response synchronously through the following solution :-    a. Created 2 apex:commandbuttons :-        1. <apex:commandButton value="Save and Send Activation Email" action="{!CreateContact}"  rerender="junkpanel" oncomplete="callSimulateUserSave()">            Note :- Oncomplete will not work if you dont have a rerender attribute. So just try refreshing a junk panel.        2. <apex:commandButton value="SimulateUserSave" id="SimulateUserSave" action="{!SaveUser}"  style="display:none;margin-left:5px;"/>        Have a junk panel as well just for rerendering  :-        <apex:outputPanel id="junkpanel"></apex:outputPanel>    b. Created this javascript function which is called from first button's oncomplete and clicks the second button :-                function callSimulateUserSave()                {                    // Specify the id of the button that needs to be clicked. This id is based on the Apex Component Hierarchy.                    // You will not get this value if you dont have the id attribute in the button which needs to be clicked from javascript                    // If you have any doubt in getting this value. Just hover over the button using Chrome developer tools to get the id.                    // But it will show like theForm:SimulateUserSave but you need to replace the colon with a dot here.                    // Note :- I have given display:none in the style of the second button to make sure that, it is not visible for the user.                    var mybtn=document.getElementById('{!$Component.theForm.SimulateUserSave}');                                    mybtn.click();                }    c. Apex Methods CreateContact and SaveUser are the pagereference methods which contains the code to create contact and user respectively.       After inserting the user inside the second apex method you can just set some public Properties in the page,        for ex:- created userid to get the user details and display in the page to show the acknowledgement to the users that the User is created.

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  • Re-generating SQL Server Logins

    SQL Server stores all login information on security catalog system tables. By querying the system tables, SQL statements can be re-generated to recover logins, including password, default schema/database, server/database role assignments, and object level permissions. A comprehensive permission report can also be produced by combining information from the system metadata. The Future of SQL Server Monitoring "Being web-based, SQL Monitor 2.0 enables you to check on your servers from almost any location" Jonathan Allen.Try SQL Monitor now.

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  • Another Custom Property Locator: a Library of Books

    - by Cindy McMullen
    Introduction The previous post gave an introduction to custom property locators and showed how create one using JDeveloper.  This post continues on the custom locator theme, with a slightly more complex locator: a library of books.  It demonstrates using the DAO pattern to delegate data access from the Locator, which is likely how many actual backing stores will integrate with the Locator.  You can imagine, rather than a library of books, the data store might be a user database of sorts.  The same sort of pattern would apply. This post uses the BookLocator example originally shown in the WebCenter documentation, but has: updated the source code to reflect the final Property APIs includes the steps for generating the namespace and property definition files via JDeveloper detailed usage of the PropertyService APIs Getting Started If you're new to JDeveloper, you might want to check out this tutorial.  There is also the "Jump-Start to using Personalization" blog post that you might find useful.  Otherwise, if you're already familiar with both, you can skip those tutorials and jump right in to using JDeveloper. Download the BookLocator.zip file (which has been updated from the original post) and unzip it to a new directory.  Start JDeveloper, navigate to the BookLocator.jws file, and open it.   It should look something like this: The Properties Namespace file contains the property definitions and property set definitions you define.  It is explained more in detail in the Namespace documentation.  Although this example doesn't show it, the property set definitions have the ability to reference multiple locators per property.   This can be done by right-clicking on the 'Locator Info' box.  Configure the contents of the Locator Map  by editing locators and mapping them to available property names in the property set definition. Compiling, deploying, and running your locator The rest of the steps in this tutorial basically follow those in the previous blog on custom locators, and won't be repeated here.   A scenario to invoke your locator is included with the sample app: see BookProperties.scenarios_diagram above.  Summary This post demonstrates a simple library of books accessed by the BookPropertyLocator via the DAO layer.  This is a useful pattern for more realistic property retrievals, such as a backing user store.  It also points out the possibility of retrieving properties from multiple locators, which would be quite handy to retrieve user attributes from multiple sources.

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  • How can I achieve strong typing with a component messaging system?

    - by Vaughan Hilts
    I'm looking at implementing a messaging system in my entity component system. I've deduced that I can use an event / queue for passing messages, but right now, I just use a generic object and cast out the data I want. I also considered using a dictionary. I see a lot of information on this, but they all involve a lot of casting and guessing. Is there any way to do this elegantly and keep strong typing on my messages?

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  • Attaching two objects and changing their world matrices accordingly

    - by A-Type
    I'm having a hard time wrapping my head around the transformations required to bind two objects together in either a two-way or one-way relationship. I will need to implement both types. For the first case, I want to be able to 'couple' two ships together in space. The ships have different mass, of course. Forces applied to either ship will use combined mass and moment of inertia to calculate and move both ships. The trick is, being sure that the point at which they are coupled remains the same, and they don't move at all relative to each other. The second case is similar: I want a ship to be able to enter the atmosphere of a planet and move relative to the planet. The planet will be orbiting the sun, which is fixed at 0,0,0. Essentially, when the ship is sitting still outside of the atmosphere, the planet will move past it on its course-- but when the ship is sitting still inside the atmosphere, it moves and rotates with the planet, so that it is always relative to the horizon. Essentially, the vertices which make up the ship are now transformed just like the ones that make up the planet, except that the ship can move itself around relative to the planet. I get the feeling I can implement both of these with the same code. Essentially, I am thinking of giving each object (which I call Fixtures) a list of "slave" Fixtures onto which that Fixture's world matrix is imposed. So, this would be the planet imposing its world on any contained ships. In the case of coupling, I would simply make each ship a slave of the other, somehow. Obviously I can't just multiply the ship's world matrix by the planet's, or each ship by the others. What I'd like some help with is what calculations to make in order to get a nice, seamless relative world to the other object. I was thinking maybe I could just multiply the world of the slave by the inverse of the master, but then when you couple two ships you would lose all that world data. So, perhaps I need an intermediate "world" which is the absolute world, but use a secondary "final world" to actually transform the objects?

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  • Am I deluding myself? Business analyst transition to programmer

    - by Ryan
    Current job: Working as the lead business analyst for a Big 4 firm, leading a team of developers and testers working on a large scale re-platforming project (4 onshore dev, 4 offshore devs, several onshore/offshore testers). Also work in a similar capacity on other smaller scale projects. Extent of my role: Gathering/writing out requirements, creating functional specifications, designing the UI (basically mapping out all front-end aspects of the system), working closely with devs to communicate/clarify requirements and come up with solutions when we hit roadblocks, writing test cases (and doing much of the testing), working with senior management and key stakeholders, managing beta testers, creating user guides and leading training sessions, providing key technical support. I also write quite a few macros in Excel using VBA (several of my macros are now used across the entire firm, so there are maybe around 1000 people using them) and use SQL on a daily basis, both on the SQL compact files the program relies on, our SQL Server data and any Access databases I create. The developers feel that I am quite good in this role because I understand a lot about programming, inherent system limitations, structure of the databases, etc so it's easier for me to communicate ideas and come up with suggestions when we face problems. What really interests me is developing software. I do a fair amount of programming in VBA and have been wanting to learn C# for awhile (the dev team uses C# - I review code occasionally for my own sake but have not had any practical experience using it). I'm interested in not just the business process but also the technical side of things, so the traditional BA role doesn't really whet my appetite for the kind of stuff I want to do. Right now I have a few small projects that managers have given me and I'm finding new ways to do them (like building custom Access applications), so there's a bit here and there to keep me interested. My question is this: what I would like to do is create custom Excel or Access applications for small businesses as a freelance business (working as a one-man shop; maybe having an occasional contractor depending on a project's complexity). This would obviously start out as a part-time venture while I have a day job, but eventually become a full-time job. Am I deluding myself to thinking I can go from BA/part-time VBA programmer to making a full-time go of a freelance business (where I would be starting out just writing custom Excel/Access apps in VBA)? Or is this type of thing not usually attempted until someone gains years of full-time programming experience? And is there even a market for these types of applications amongst small businesses (and maybe medium-sized) businesses?

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  • Is code like this a "train wreck" (in violation of Law of Demeter)?

    - by Michael Kjörling
    Browsing through some code I've written, I came across the following construct which got me thinking. At a first glance, it seems clean enough. Yes, in the actual code the getLocation() method has a slightly more specific name which better describes exactly which location it gets. service.setLocation(this.configuration.getLocation().toString()); In this case, service is an instance variable of a known type, declared within the method. this.configuration comes from being passed in to the class constructor, and is an instance of a class implementing a specific interface (which mandates a public getLocation() method). Hence, the return type of the expression this.configuration.getLocation() is known; specifically in this case, it is a java.net.URL, whereas service.setLocation() wants a String. Since the two types String and URL are not directly compatible, some sort of conversion is required to fit the square peg in the round hole. However, according to the Law of Demeter as cited in Clean Code, a method f in class C should only call methods on C, objects created by or passed as arguments to f, and objects held in instance variables of C. Anything beyond that (the final toString() in my particular case above, unless you consider a temporary object created as a result of the method invocation itself, in which case the whole Law seems to be moot) is disallowed. Is there a valid reasoning why a call like the above, given the constraints listed, should be discouraged or even disallowed? Or am I just being overly nitpicky? If I were to implement a method URLToString() which simply calls toString() on a URL object (such as that returned by getLocation()) passed to it as a parameter, and returns the result, I could wrap the getLocation() call in it to achieve exactly the same result; effectively, I would just move the conversion one step outward. Would that somehow make it acceptable? (It seems to me, intuitively, that it should not make any difference either way, since all that does is move things around a little. However, going by the letter of the Law of Demeter as cited, it would be acceptable, since I would then be operating directly on a parameter to a function.) Would it make any difference if this was about something slightly more exotic than calling toString() on a standard type? When answering, do keep in mind that altering the behavior or API of the type that the service variable is of is not practical. Also, for the sake of argument, let's say that altering the return type of getLocation() is also impractical.

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  • What is a good resource for learning how the .Net Framework works? [on hold]

    - by Till Death Developer
    I've been developing web apps, for a while now so i know how to get the job done, what i don't know is how every thing really works, i know some but the rest i can't get a grasp on like how abstract works, what happens when i instantiate an object from a class that inherits from an abstract class?, where things get stored Heap vs Stack?, in other words the Interview questions that i suck at, so any advice would be great, books, videos, online courses, whatever you can provide would really help me.

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  • Was I wrong about JavaScript?

    - by jboyer
    Yes, I was. Recently, I’ve taken a good hard look at JavaScript. I’ve used it before but mostly in the capacity of web design. Using JQuery to make your web page do cool stuff is different than really creating a JavaScript application using all of the language constructs. What I’m finding as I use it more is that I may have been wrong about my assumptions about it. Let me explain.   I enjoyed doing cool stuff with JQuery but the limited experience with JavaScript as a language coupled with the bad things that I heard about it led me to not have any real interest in it. However, JavaScript is ubiquitous on the web and if I want to do any web development, which I do, I need to learn it. So here I am, diving deep into the language with the help of the JavaScript Fundamentals training course at Pluralsight (great training for a low price) and the JavaScript: The Good Parts book by Douglas Crockford.   Now, there are certainly parts of JavaScript that are bad. I think these are well known by any developer that uses it. The parts that I feel are especially egregious are the following: The global object null vs. undefined truthy and falsy limited (nearly nonexistent) scoping ‘==’ and ‘===’ (I just don’t get the reason for coercion)   However, what I am finding hiding under the covers of the bad things is a good language. I am finding that I am legitimately enjoying JavaScript. This I was not expecting. I’m not going to go into a huge dissertation on what I like about it, but some things include: Object literal notation dynamic typing functional style (JavaScript: The Good Parts describes it as LISP in C clothing) JSON (better than XML) There are parts of JavaScript that seem strange to OOP developers like myself. However, just because it is different or seems strange does not mean it is bad. Some differences are quite interesting and useful.   I feel that it is important for developers to challenge their assumptions and also to be able to admit when they are wrong on a topic. Many different situations can arise that lead to this, such as choosing the wrong technology for a problem’s solution, misunderstanding the requirements, etc. I decided to challenge my assumptions about JavaScript instead of moving straight into CoffeeScript or Dart. After exploring it, I find that I am beginning to enjoy it the more I use it. As long as there are those like Crockford to help guide me in the right way to code in JavaScript, I can create elegant and efficient solutions to problems and add another ‘arrow’ to the ‘quiver’, so to speak. I do still intend to learn CoffeeScript to see what the hub-bub is about, but now I no longer have to be afraid of JavaScript as a legitimate programming language.   Has something similar ever happened to you? Tell me about it in the comments below.

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  • Which physics phenomenons can be simulated properly with Box2d or bullet physics? [on hold]

    - by user3585425
    Knowing that box2d or bullet physics can't simulate Newton's cradle (because of multiple bodies being in contact at the same time if I understand correctly), is there a sets of physics phenomenons that imply two or more objects that still can be simulated properly ? For example, I'm thinking about lightweight objects launched towards heavyweight objects. If the object is destroyed on contact, this would not make a difference if the energy is not transmitted correctly on impact.

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  • Unit-testing code that relies on untestable 3rd party code

    - by DudeOnRock
    Sometimes, especially when working with third party code, I write unit-test specific code in my production code. This happens when third party code uses singletons, relies on constants, accesses the file-system/a resource I don't want to access in a test situation, or overuses inheritance. The form my unit-test specific code takes is usually the following: if (accessing or importing a certain resource fails) I assume this is a test case and load a mock object Is this poor form, and if it is, what is normally done when writing tests for code that uses untestable third party code?

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  • Databinding a .Net WinForms ComboBox to an Enum

    - by Tim Huffam
    This is quite simple... Define the enum eg: public enum MyEnum{ ItemOne, ItemTwo, } Within the form set the datasource of the combobox to the values of the enum eg: myCombo.DataSource = System.Enum.GetValues(typeof(MyEnum)); To have the combo auto select a value based on a bound object, set the databinding of the combo eg: class MyObject{ private MyEnum myEnumProperty; public MyEnum MyEnumProperty{get {return myEnumProperty;}} } MyObject myObj = new MyObject(); myCombo.DataBindings.Add(new Binding("SelectedIndex", myObject, "MyEnumProperty");

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  • What problems can arise from emulating concepts from another languages?

    - by Vandell
    I've read many times on the web that if your language doesn't support some concept, for example, object orientation, or maybe function calls, and it's considered a good practice in this other context, you should do it. The only problem I can see now is that other programmers may find your code too different than the usual, making it hard for them to program. What other problems do you think may arise from this?

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  • Java heap space

    - by java_mouse
    In Java/JVM, why do we call the memory place where Java creates objects as "Heap"? Does it use the Heap Data Structure to create/remove/maintain the objects? As I read in the documentation of Heap data structure, the algorithm compares the objects with existing nodes and places them in such a way that Parent object is "greater" than the children. ( Or "lesser" in case of min heap). So in JVM, how are the objects compared against each other before placing them in the heap?

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  • ScaleOut StateServer Product Review

    EggHeadCafe has a free drawing for a license to ScaleOut StateServer. You will want want to enter your name in for this one! Learn how to share objects from their in memory object store across windows forms, wcf, asp.net, and windows services.  read moreBy Robbe MorrisDid you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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  • 2D camera perspective projection from 3D coordinates -- HOW?

    - by Jack
    I am developing a camera for a 2D game with a top-down view that has depth. It's almost a 3D camera. Basically, every object has a Z even though it is in 2D, and similarly to parallax layers their position, scale and rotation speed vary based on their Z. I guess this would be a perspective projection. But I am having trouble converting the objects' 3D coordinates into the 2D space of the screen so that everything has correct perspective and scale. I never learned matrices though I did dig the topic a bit today. I tried without using matrices thanks to this article but every attempt gave awkward results. I'm using ActionScript 3 and Flash 11+ (Starling), where the screen coordinates work like this: Left-handed coordinates system illustration I can explain further what I did if you want to help me sort out what's wrong, or you can directly tell me how you would do it properly. In case you prefer the former, read on. These are images showing the formulas I used: upload.wikimedia.org/math/1/c/8/1c89722619b756d05adb4ea38ee6f62b.png upload.wikimedia.org/math/d/4/0/d4069770c68cb8f1aa4b5cfc57e81bc3.png (Sorry new users can't post images, but both are from the wikipedia article linked above, section "Perspective projection". That's where you'll find what all variables mean, too) The long formula is greatly simplified because I believe a normal top-down 2D camera has no X/Y/Z rotation values (correct ?). Then it becomes d = a - c. Still, I can't get it to work. Maybe you could explain what numbers I should put in a(xyz), c(xyz), theta(xyz), and particularly, e(xyz) ? I don't quite get how e is different than c in my case. c.z is also an issue to me. If the Z of the camera's target object is 0, should the camera's Z be something like -600 ? ( = focal length of 600) Whatever I do, it's wrong. I only got it to work when I used arbitrary calculations that "looked" right, like most cameras with parallax layers seem to do, but that's fake! ;) If I want objects to travel between Z layers I might as well do it right. :) Thanks a lot for your help!

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  • As the current draft stands, what is the most significant change the "National Strategy for Trusted Identities in Cyberspace" will provoke?

    - by mfg
    A current draft of the "National Strategy for Trusted Identities in Cyberspace" has been posted by the Department of Homeland Security. This question is not asking about privacy or constitutionality, but about how this act will impact developers' business models and development strategies. When the post was made I was reminded of Jeff's November blog post regarding an internet driver's license. Whether that is a perfect model or not, both approaches are attempting to handle a shared problem (of both developers and end users): How do we establish an online identity? The question I ask here is, with respect to the various burdens that would be imposed on developers and users, what are some of the major, foreseeable implementation issues that will arise from the current U.S. Government's proposed solution? For a quick primer on the setup, jump to page 12 for infrastructure components, here are two stand-outs: An Identity Provider (IDP) is responsible for the processes associated with enrolling a subject, and establishing and maintaining the digital identity associated with an individual or NPE. These processes include identity vetting and proofing, as well as revocation, suspension, and recovery of the digital identity. The IDP is responsible for issuing a credential, the information object or device used during a transaction to provide evidence of the subject’s identity; it may also provide linkage to authority, roles, rights, privileges, and other attributes. The credential can be stored on an identity medium, which is a device or object (physical or virtual) used for storing one or more credentials, claims, or attributes related to a subject. Identity media are widely available in many formats, such as smart cards, security chips embedded in PCs, cell phones, software based certificates, and USB devices. Selection of the appropriate credential is implementation specific and dependent on the risk tolerance of the participating entities. Here are the first considered actionable components of the draft: Action 1: Designate a Federal Agency to Lead the Public/Private Sector Efforts Associated with Achieving the Goals of the Strategy Action 2: Develop a Shared, Comprehensive Public/Private Sector Implementation Plan Action 3:Accelerate the Expansion of Federal Services, Pilots, and Policies that Align with the Identity Ecosystem Action 4:Work Among the Public/Private Sectors to Implement Enhanced Privacy Protections Action 5:Coordinate the Development and Refinement of Risk Models and Interoperability Standards Action 6: Address the Liability Concerns of Service Providers and Individuals Action 7: Perform Outreach and Awareness Across all Stakeholders Action 8: Continue Collaborating in International Efforts Action 9: Identify Other Means to Drive Adoption of the Identity Ecosystem across the Nation

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  • Problem in installing player/gazebo

    - by usama yaseen
    I am using ubuntu 10.04 (64-bit), i have sucessfully installed all the dependancies of player and gazebo, then i installed player 3.01 and then gazebo 0.9,Now the when i run this gazebo worlds/pioneer2dx.world I get a gazebo interface, everything is ok uptill now, but when i run this cd gazebo/player player gazebo.cfg player: error while loading shared libraries: libplayerdrivers.so.3.0: cannot open shared object file: No such file or directory I guess the problem is somewhere in the environmental variables, can anyone please help me to solve this?

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  • T-SQL Tuesday #006 Round-up!

    - by Mike C
    T-SQL Tuesday this month was all about LOB (large object) data. Thanks to all the great bloggers out there who participated! The participants this month posted some very impressive articles with information running the gamut from Reporting Services to SQL Server spatial data types to BLOB-handling in SSIS. One thing I noticed immediately was a trend toward articles about spatial data (SQL Server 2008 Geography and Geometry data types, a very fun topic to explore if you haven’t played around with...(read more)

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  • Image first loaded, then it isn't? (XNA)

    - by M0rgenstern
    I am very confused at the Moment. I have the following Class: (Just a part of the class): public class GUIWindow { #region Static Fields //The standard image for windows. public static IngameImage StandardBackgroundImage; #endregion } IngameImage is just one of my own classes, but actually it contains a Texture2D (and some other things). In another class I load a list of GUIButtons by deserializing a XML file. public static GUI Initializazion(string pXMLPath, ContentManager pConMan) { GUI myGUI = pConMan.Load<GUI>(pXMLPath); GUIWindow.StandardBackgroundImage = new IngameImage(pConMan.Load<Texture2D>(myGUI.WindowStandardBackgroundImagePath), Vector2.Zero, 1024, 600, 1, 0, Color.White, 1.0f, true, false, false); System.Console.WriteLine("Image loaded? " + (GUIWindow.StandardBackgroundImage.ImageStrip != null)); myGUI.Windows = pConMan.Load<List<GUIWindow>>(myGUI.GUIFormatXMLPath); System.Console.WriteLine("Windows loaded"); return myGUI; } Here this line: System.Console.WriteLine("Image loaded? " + (GUIWindow.StandardBackgroundImage.ImageStrip != null)); Prints "true". To load the GUIWindows I need an "empty" constructor, which looks like that: public GUIWindow() { Name = ""; Buttons = new List<Button>(); ImagePath = ""; System.Console.WriteLine("Image loaded? (In win) " + (GUIWindow.StandardBackgroundImage.ImageStrip != null)); //Image = new IngameImage(StandardBackgroundImage); //System.Console.WriteLine( //Image.IsActive = false; SelectedButton = null; IsActive = false; } As you can see, I commented lines out in the constructor. Because: Otherwise this would crash. Here the line System.Console.WriteLine("Image loaded? (In win) " + (GUIWindow.StandardBackgroundImage.ImageStrip != null)); Doesn't print anything, it just crashes with the following errormessage: Building content threw NullReferenceException: Object reference not set to an object instance. Why does this happen? Before the program wants to load the List, it prints "true". But in the constructor, so in the loading of the list it prints "false". Can anybody please tell me why this happens and how to fix it?

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  • there is no attribute "border"

    - by ptahiliani
    Sometimes we got this error message when we try to validate our asp.net website on w3c. To solve this error you need to write the PreRender event. Here is the complete event: Protected Sub Page_PreRender(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.PreRender         imgBtnGo.Style.Remove(HtmlTextWriterStyle.BorderWidth)         imgBtnGo.Attributes.Remove("border") End Sub

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  • Caching items in Orchard

    - by Bertrand Le Roy
    Orchard has its own caching API that while built on top of ASP.NET's caching feature adds a couple of interesting twists. In addition to its usual work, the Orchard cache API must transparently separate the cache entries by tenant but beyond that, it does offer a more modern API. Here's for example how I'm using the API in the new version of my Favicon module: _cacheManager.Get( "Vandelay.Favicon.Url", ctx => { ctx.Monitor(_signals.When("Vandelay.Favicon.Changed")); var faviconSettings = ...; return faviconSettings.FaviconUrl; }); .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } There is no need for any code to test for the existence of the cache entry or to later fill that entry. Seriously, how many times have you written code like this: var faviconUrl = (string)cache["Vandelay.Favicon.Url"]; if (faviconUrl == null) { faviconUrl = ...; cache.Add("Vandelay.Favicon.Url", faviconUrl, ...); } Orchard's cache API takes that control flow and internalizes it into the API so that you never have to write it again. Notice how even casting the object from the cache is no longer necessary as the type can be inferred from the return type of the Lambda. The Lambda itself is of course only hit when the cache entry is not found. In addition to fetching the object we're looking for, it also sets up the dependencies to monitor. You can monitor anything that implements IVolatileToken. Here, we are monitoring a specific signal ("Vandelay.Favicon.Changed") that can be triggered by other parts of the application like so: _signals.Trigger("Vandelay.Favicon.Changed"); In other words, you don't explicitly expire the cache entry. Instead, something happens that triggers the expiration. Other implementations of IVolatileToken include absolute expiration or monitoring of the files under a virtual path, but you can also come up with your own.

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  • NHibernate Session Load vs Get when using Table per Hierarchy. Always use ISession.Get&lt;T&gt; for TPH to work.

    - by Rohit Gupta
    Originally posted on: http://geekswithblogs.net/rgupta/archive/2014/06/01/nhibernate-session-load-vs-get-when-using-table-per-hierarchy.aspxNHibernate ISession has two methods on it : Load and Get. Load allows the entity to be loaded lazily, meaning the actual call to the database is made only when properties on the entity being loaded is first accessed. Additionally, if the entity has already been loaded into NHibernate Cache, then the entity is loaded directly from the cache instead of querying the underlying database. ISession.Get<T> instead makes the call to the database, every time it is invoked. With this background, it is obvious that we would prefer ISession.Load<T> over ISession.Get<T> most of the times for performance reasons to avoid making the expensive call to the database. let us consider the impact of using ISession.Load<T> when we are using the Table per Hierarchy implementation of NHibernate. Thus we have base class/ table Animal, there is a derived class named Snake with the Discriminator column being Type which in this case is “Snake”. If we load This Snake entity using the Repository for Animal, we would have a entity loaded, as shown below: public T GetByKey(object key, bool lazy = false) { if (lazy) return CurrentSession.Load<T>(key); return CurrentSession.Get<T>(key); } var tRepo = new NHibernateReadWriteRepository<TPHAnimal>(); var animal = tRepo.GetByKey(new Guid("602DAB56-D1BD-4ECC-B4BB-1C14BF87F47B"), true); var snake = animal as Snake; snake is null As you can see that the animal entity retrieved from the database cannot be cast to Snake even though the entity is actually a snake. The reason being ISession.Load prevents the entity to be cast to Snake and will throw the following exception: System.InvalidCastException :  Message=Unable to cast object of type 'TPHAnimalProxy' to type 'NHibernateChecker.Model.Snake'. Thus we can see that if we lazy load the entity using ISession.Load<TPHAnimal> then we get a TPHAnimalProxy and not a snake. =============================================================== However if do not lazy load the same cast works perfectly fine, this is since we are loading the entity from database and the entity being loaded is not a proxy. Thus the following code does not throw any exceptions, infact the snake variable is not null: var tRepo = new NHibernateReadWriteRepository<TPHAnimal>(); var animal = tRepo.GetByKey(new Guid("602DAB56-D1BD-4ECC-B4BB-1C14BF87F47B"), false); var snake = animal as Snake; if (snake == null) { var snake22 = (Snake) animal; }

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