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  • Removing Barriers to Create Effective Data Models

    After years of creating and maintaining data models, I have started to notice common barriers that decrease the accuracy and usefulness of models. In my opinion, the main causes of these barriers are the lack of knowledge and communication from within a company. The lack of knowledge in regards to data models or data modeling can take many forms. Company Culture Knowledge Whether documented or undocumented, existing business rules of a company can affect how data is modeled. For example, if a company only allows 1 assigned person per customer to be able to manipulate a customer’s record then then a data model that includes an associated table that joins customers and employee’s would be unneeded because that would allow for the possibility of multiple employees to handle a customer because of the potential for a many to many relationship between Customers and Employees. Technical Knowledge Depending on the data modeler’s proficiency in modeling data they can inadvertently cause issues and/or complications with a design without even noticing. It is important that companies share data modeling responsibilities so that the models are developed from multiple perspectives of a system, company and the original problem.  In addition, the tools that a company selects to create data models can also affect the accuracy of the model if designer are not familiar with the tools or the tools are too complex to use for the designer. Existing System Knowledge In order for a data modeler to model data for an existing system so that new changes can be applied to a system then they need to at least know the basic concepts of a system so that they can work within it. This will promote reusability of data and prevent the chance of duplicating data. Project Knowledge This should be pretty obvious, but it is very hard to create an accurate data model without knowing what data needs to be modeled. I have always found it strange that I have been asked to start modeling data prior to a client formalizing any requirements. Usually when this happens I have to make several iterations to a model, and the client still does not know exactly what they want.  In addition additional issues can arise when certain stakeholders of a project are not consulted prior to the design or after the project is over because it can cause miss understandings and confusion by the end user as well as possibly not solving the original problem for which a project is intended to solve. One common thread between each type of knowledge is that they can all be avoided through the use of good communication. For example, if a modeler is new to a company then they should ask older employees about any business specific rules that may be documented or undocumented that must be applied to projects in general. Furthermore, if a modeler is not really familiar with a specific data modeling software then they need to speak up and ask for help form other employees or their manager. This will not only help the modeler in the project, but also help them in future projects that they do for the company. Additionally, if a project is not clearly defined prior to a data modeler being assigned the modeling project then it is their responsibility to communicate with the other stakeholders to clarify any part of a project that is unclear so that the data model that is created is accurately aligned with a project.

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  • Come up with a real-world problem in which only the best solution will do (a problem from Introduction to algorithms) [closed]

    - by Mike
    EDITED (I realized that the question certainly needs a context) The problem 1.1-5 in the book of Thomas Cormen et al Introduction to algorithms is: "Come up with a real-world problem in which only the best solution will do. Then come up with one in which a solution that is “approximately” the best is good enough." I'm interested in its first statement. And (from my understanding) it is asked to name a real-world problem where only the exact solution will work as opposed to a real-world problem where good-enough solution will be ok. So what is the difference between the exact and good enough solution. Consider some physics problem for example the simulation of the fulid flow in the permeable medium. To make this simulation happen some simplyfing assumptions have to be made when deriving a mathematical model. Otherwise the model becomes at least complex and unsolvable. Virtually any particle in the universe has its influence on the fluid flow. But not all particles are equal. Those that form the permeable medium are much more influental than the ones located light years away. Then when the mathematical model needs to be solved an exact solution can rarely be found unless the mathematical model is simple enough (wich probably means the model isn't close to reality). We take an approximate numerical method and after hours of coding and days of verification come up with the program or algorithm which is a solution. And if the model and an algorithm give results close to a real problem by some degree that is good enough soultion. Its worth noting the difference between exact solution algorithm and exact computation result. When considering real-world problems and real-world computation machines I believe all physical problems solutions where any calculations are taken can not be exact because universal physical constants are represented approximately in the computer. Any numbers are represented with the limited precision, at least limited by amount of memory available to computing machine. I can imagine plenty of problems where good-enough, good to some degree solution will work, like train scheduling, automated trading, satellite orbit calculation, health care expert systems. In that cases exact solutions can't be derived due to constraints on computation time, limitations in computer memory or due to the nature of problems. I googled this question and like what this guy suggests: there're kinds of mathematical problems that need exact solutions (little note here: because the question is taken from the book "Introduction to algorithms" the term "solution" means an algorithm or a program, which in this case gives exact answer on each input). But that's probably more of theoretical interest. So I would like to narrow down the question to: What are the real-world practical problems where only the best (exact) solution algorithm or program will do (but not the good-enough solution)? There are problems like breaking of cryptographic ciphers where only exact solution matters in practice and again in practice the process of deciphering without knowing a secret should take reasonable amount of time. Returning to the original question this is the problem where good-enough (fast-enough) solution will do there's no practical need in instant crack though it's desired. So the quality of "best" can be understood in any sense: exact, fastest, requiring least memory, having minimal possible network traffic etc. And still I want this question to be theoretical if possible. In a sense that there may be example of computer X that has limited resource R of amount Y where the best solution to problem P is the one that takes not more than available Y for inputs of size N*Y. But that's the problem of finding solution for P on computer X which is... well, good enough. My final thought that we live in a world where it is required from programming solutions to practical purposes to be good enough. In rare cases really very very good but still not the best ones. Isn't it? :) If it's not can you provide an example? Or can you name any such unsolved problem of practical interest?

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  • Python regex to parse text file, get the items in list and count the list

    - by Nemo
    I have a text file which contains some data. I m particularly interested in finding the count of the number of items in v_dims v_dims pattern in my text file looks like this : v_dims={ "Sales", "Product Family", "Sales Organization", "Region", "Sales Area", "Sales office", "Sales Division", "Sales Person", "Sales Channel", "Sales Order Type", "Sales Number", "Sales Person", "Sales Quantity", "Sales Amount" } So I m thinking of getting all the elements in v_dims and dumping them out in a Python list. Then compute the len(mylist) to get the count of the items. The challenge is in getting all the elements of v_dims from my text file and putting them in an empty list. I m particularly interested in items in v_dims in my text file. The text file has data in the form of v_dims pattern i showed in my original post. Some data has nested patterns of v_dims. Thanks. Here's what I have tried and failed. Any help is appreciated. TIA. import re fname = "C:\Users\XXXX\Test.mrk" with open(fname, "r") as fo: content_as_string = fo.read() match = re.findall(r'v_dims={\"(.+?)\"}',content_as_string) Though I have a big text file, Here's a snippet of what's the structure of my text file version "1"; // Computer generated object language file object 'MRKR' "Main" { Data_Type=2, HeaderBlock={ Version_String="6.3 (25)" }, Printer_Info={ Orientation=0, Page_Width=8.50000000, Page_Height=11.00000000, Page_Header="", Page_Footer="", Margin_type=0, Top_Margin=0.50000000, Left_Margin=0.50000000, Bottom_Margin=0.50000000, Right_Margin=0.50000000 }, Marker_Options={ Close_All="TRUE", Hide_Console="FALSE", Console_Left="FALSE", Console_Width=217, Main_Style="Maximized", MDI_Rect={ 0, 0, 892, 1063 } }, Dives={ { Dive="A", Windows={ { View_Index=0, Window_Info={ Window_Rect={ 0, -288, 400, 1008 }, Window_Style="Maximized Front", Window_Name="Theater [Previous Qtr Diveplan-Dive A]" }, Dependent_bool="FALSE", Colset={ Dive_Type="Normal", Dimension_Name="Theater", Action_List={ Actions={ { Action_Type="Select", select_type=5 }, { Action_Type="Select", select_type=0, Key_Names={ "Theater" }, Key_Indexes={ { "AMERICAS" } } }, { Action_Type="Focus", Focus_Rows="True" }, { Action_Type="Dimensions", v_dims={ "Theater", "Product Family", "Division", "Region", "Install at Country Name", "Connect Home Type", "Connect In Type", "SymmConnect Enabled", "Connect Home Refusal Reason", "Sales Order Channel Type", "Maintained By Group", "PS Flag", "Avalanche Flag", "Product Item Family" }, Xtab_Bool="False", Xtab_Flip="False" }, { Action_Type="Select", select_type=5 }, { Action_Type="Select", select_type=0, Key_Names={ "Theater", "Product Family", "Division", "Region", "Install at Country Name", "Connect Home Type", "Connect In Type", "SymmConnect Enabled", "Connect Home Refusal Reason", "Sales Order Channel Type", "Maintained By Group", "PS Flag", "Avalanche Flag" }, Key_Indexes={ { "AMERICAS", "ATMOS", "Latin America CS Division", "37000 CS Region", "Mexico", "", "", "", "", "DIRECT", "EMC", "N", "0" } } } } }, Num_Palette_cols=0, Num_Palette_rows=0 }, Format={ Window_Type="Tabular", Tabular={ Num_row_labels=8 } } } } } }, Widget_Set={ Widget_Layout="Vertical", Go_Button=1, Picklist_Width=0, Sort_Subset_Dimensions="TRUE", Order={ } }, Views={ { Data_Type=1, dbname="Previous Qtr Diveplan", diveline_dbname="Current Qtr Diveplan", logical_name="Current Qtr Diveplan", cols={ { name="Total TSS installs", column_type="Calc[Total TSS installs]", output_type="Number", format_string="." }, { name="TSS Valid Connectivity Records", column_type="Calc[TSS Valid Connectivity Records]", output_type="Number", format_string="." }, { name="% TSS Connectivity Record", column_type="Calc[% TSS Connectivity Record]", output_type="Number" }, { name="TSS Not Applicable", column_type="Calc[TSS Not Applicable]", output_type="Number", format_string="." }, { name="TSS Customer Refusals", column_type="Calc[TSS Customer Refusals]", output_type="Number", format_string="." }, { name="% TSS Refusals", column_type="Calc[% TSS Refusals]", output_type="Number" }, { name="TSS Eligible for Physical Connectivity", column_type="Calc[TSS Eligible for Physical Connectivity]", output_type="Number", format_string="." }, { name="TSS Boxes with Physical Connectivty", column_type="Calc[TSS Boxes with Physical Connectivty]", output_type="Number", format_string="." }, { name="% TSS Physical Connectivity", column_type="Calc[% TSS Physical Connectivity]", output_type="Number" } }, dim_cols={ { name="Model", column_type="Dimension[Model]", output_type="None" }, { name="Model", column_type="Dimension[Model]", output_type="None" }, { name="Connect In Type", column_type="Dimension[Connect In Type]", output_type="None" }, { name="Connect Home Type", column_type="Dimension[Connect Home Type]", output_type="None" }, { name="SymmConnect Enabled", column_type="Dimension[SymmConnect Enabled]", output_type="None" }, { name="Theater", column_type="Dimension[Theater]", output_type="None" }, { name="Division", column_type="Dimension[Division]", output_type="None" }, { name="Region", column_type="Dimension[Region]", output_type="None" }, { name="Sales Order Number", column_type="Dimension[Sales Order Number]", output_type="None" }, { name="Product Item Family", column_type="Dimension[Product Item Family]", output_type="None" }, { name="Item Serial Number", column_type="Dimension[Item Serial Number]", output_type="None" }, { name="Sales Order Deal Number", column_type="Dimension[Sales Order Deal Number]", output_type="None" }, { name="Item Install Date", column_type="Dimension[Item Install Date]", output_type="None" }, { name="SYR Last Dial Home Date", column_type="Dimension[SYR Last Dial Home Date]", output_type="None" }, { name="Maintained By Group", column_type="Dimension[Maintained By Group]", output_type="None" }, { name="PS Flag", column_type="Dimension[PS Flag]", output_type="None" }, { name="Connect Home Refusal Reason", column_type="Dimension[Connect Home Refusal Reason]", output_type="None", col_width=177 }, { name="Cust Name", column_type="Dimension[Cust Name]", output_type="None" }, { name="Sales Order Channel Type", column_type="Dimension[Sales Order Channel Type]", output_type="None" }, { name="Sales Order Type", column_type="Dimension[Sales Order Type]", output_type="None" }, { name="Part Model Key", column_type="Dimension[Part Model Key]", output_type="None" }, { name="Ship Date", column_type="Dimension[Ship Date]", output_type="None" }, { name="Model Number", column_type="Dimension[Model Number]", output_type="None" }, { name="Item Description", column_type="Dimension[Item Description]", output_type="None" }, { name="Customer Classification", column_type="Dimension[Customer Classification]", output_type="None" }, { name="CS Customer Name", column_type="Dimension[CS Customer Name]", output_type="None" }, { name="Install At Customer Number", column_type="Dimension[Install At Customer Number]", output_type="None" }, { name="Install at Country Name", column_type="Dimension[Install at Country Name]", output_type="None" }, { name="TLA Serial Number", column_type="Dimension[TLA Serial Number]", output_type="None" }, { name="Product Version", column_type="Dimension[Product Version]", output_type="None" }, { name="Avalanche Flag", column_type="Dimension[Avalanche Flag]", output_type="None" }, { name="Product Family", column_type="Dimension[Product Family]", output_type="None" }, { name="Project Number", column_type="Dimension[Project Number]", output_type="None" }, { name="PROJECT_STATUS", column_type="Dimension[PROJECT_STATUS]", output_type="None" } }, Available_Columns={ "Total TSS installs", "TSS Valid Connectivity Records", "% TSS Connectivity Record", "TSS Not Applicable", "TSS Customer Refusals", "% TSS Refusals", "TSS Eligible for Physical Connectivity", "TSS Boxes with Physical Connectivty", "% TSS Physical Connectivity", "Total Installs", "All Boxes with Valid Connectivty Record", "% All Connectivity Record", "Overall Refusals", "Overall Refusals %", "All Eligible for Physical Connectivty", "Boxes with Physical Connectivity", "% All with Physical Conectivity" }, Remaining_columns={ { name="Total Installs", column_type="Calc[Total Installs]", output_type="Number", format_string="." }, { name="All Boxes with Valid Connectivty Record", column_type="Calc[All Boxes with Valid Connectivty Record]", output_type="Number", format_string="." }, { name="% All Connectivity Record", column_type="Calc[% All Connectivity Record]", output_type="Number" }, { name="Overall Refusals", column_type="Calc[Overall Refusals]", output_type="Number", format_string="." }, { name="Overall Refusals %", column_type="Calc[Overall Refusals %]", output_type="Number" }, { name="All Eligible for Physical Connectivty", column_type="Calc[All Eligible for Physical Connectivty]", output_type="Number" }, { name="Boxes with Physical Connectivity", column_type="Calc[Boxes with Physical Connectivity]", output_type="Number" }, { name="% All with Physical Conectivity", column_type="Calc[% All with Physical Conectivity]", output_type="Number" } }, calcs={ { name="Total TSS installs", definition="Total[Total TSS installs]", ts_flag="Not TS Calc" }, { name="TSS Valid Connectivity Records", definition="Total[PS Boxes w/ valid connectivity record (1=yes)]", ts_flag="Not TS Calc" }, { name="% TSS Connectivity Record", definition="Total[PS Boxes w/ valid connectivity record (1=yes)] /Total[Total TSS installs]", ts_flag="Not TS Calc" }, { name="TSS Not Applicable", definition="Total[Bozes w/ valid connectivity record (1=yes)]-Total[Boxes Eligible (1=yes)]-Total[TSS Refusals]", ts_flag="Not TS Calc" }, { name="TSS Customer Refusals", definition="Total[TSS Refusals]", ts_flag="Not TS Calc" }, { name="% TSS Refusals", definition="Total[TSS Refusals]/Total[PS Boxes w/ valid connectivity record (1=yes)]", ts_flag="Not TS Calc" }, { name="TSS Eligible for Physical Connectivity", definition="Total[TSS Eligible]-Total[Exception]", ts_flag="Not TS Calc" }, { name="TSS Boxes with Physical Connectivty", definition="Total[PS Physical Connectivity] - Total[PS Physical Connectivity, SymmConnect Enabled=\"Capable not enabled\"]", ts_flag="Not TS Calc" }, { name="% TSS Physical Connectivity", definition="Total[Boxes w/ phys conn]/Total[Boxes Eligible (1=yes)]", ts_flag="Not TS Calc" }, { name="Total Installs", definition="Total[Total Installs]", ts_flag="Not TS Calc" }, { name="All Boxes with Valid Connectivty Record", definition="Total[Bozes w/ valid connectivity record (1=yes)]", ts_flag="Not TS Calc" }, { name="% All Connectivity Record", definition="Total[Bozes w/ valid connectivity record (1=yes)]/Total[Total Installs]", ts_flag="Not TS Calc" }, { name="Overall Refusals", definition="Total[Overall Refusals]", ts_flag="Not TS Calc" }, { name="Overall Refusals %", definition="Total[Overall Refusals]/Total[Bozes w/ valid connectivity record (1=yes)]", ts_flag="Not TS Calc" }, { name="All Eligible for Physical Connectivty", definition="Total[Boxes Eligible (1=yes)]-Total[Exception]", ts_flag="Not TS Calc" }, { name="Boxes with Physical Connectivity", definition="Total[Boxes w/ phys conn]-Total[Boxes w/ phys conn,SymmConnect Enabled=\"Capable not enabled\"]", ts_flag="Not TS Calc" }, { name="% All with Physical Conectivity", definition="Total[Boxes w/ phys conn]/Total[Boxes Eligible (1=yes)]", ts_flag="Not TS Calc" } }, merge_type="consolidate", merge_dbs={ { dbname="connectivityallproducts.mdl", diveline_dbname="/DI_PSREPORTING/connectivityallproducts.mdl" } }, skip_constant_columns="FALSE", categories={ { name="Geography", dimensions={ "Theater", "Division", "Region", "Install at Country Name" } }, { name="Mappings and Flags", dimensions={ "Connect Home Type", "Connect In Type", "SymmConnect Enabled", "Connect Home Refusal Reason", "Sales Order Channel Type", "Maintained By Group", "Customer Installable", "PS Flag", "Top Level Flag", "Avalanche Flag" } }, { name="Product Information", dimensions={ "Product Family", "Product Item Family", "Product Version", "Item Description" } }, { name="Sales Order Info", dimensions={ "Sales Order Deal Number", "Sales Order Number", "Sales Order Type" } }, { name="Dates", dimensions={ "Item Install Date", "Ship Date", "SYR Last Dial Home Date" } }, { name="Details", dimensions={ "Item Serial Number", "TLA Serial Number", "Part Model Key", "Model Number" } }, { name="Customer Infor", dimensions={ "CS Customer Name", "Install At Customer Number", "Customer Classification", "Cust Name" } }, { name="Other Dimensions", dimensions={ "Model" } } }, Maintain_Category_Order="FALSE", popup_info="false" } } };

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  • Can I use a single DateTime field on the Entity Framework model side when the value is stored in a set of Int fields in the actual database?

    - by Ivan
    The actual table in the database has separate integer fields for storing year, month, day, hour and minute values (all in UTC) (seconds and milliseconds are irrelevant for my task and considered equal to zero). Needless to say it would be of great convenience to have just one field of DateTime type on the application side and hide all the conversion under the cover of the Entity Framework model code. Any directions on how to do that? I am not very experienced with Entity Framework yet.

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  • What’s new in ASP.NET 4.0: Core Features

    - by Rick Strahl
    Microsoft released the .NET Runtime 4.0 and with it comes a brand spanking new version of ASP.NET – version 4.0 – which provides an incremental set of improvements to an already powerful platform. .NET 4.0 is a full release of the .NET Framework, unlike version 3.5, which was merely a set of library updates on top of the .NET Framework version 2.0. Because of this full framework revision, there has been a welcome bit of consolidation of assemblies and configuration settings. The full runtime version change to 4.0 also means that you have to explicitly pick version 4.0 of the runtime when you create a new Application Pool in IIS, unlike .NET 3.5, which actually requires version 2.0 of the runtime. In this first of two parts I'll take a look at some of the changes in the core ASP.NET runtime. In the next edition I'll go over improvements in Web Forms and Visual Studio. Core Engine Features Most of the high profile improvements in ASP.NET have to do with Web Forms, but there are a few gems in the core runtime that should make life easier for ASP.NET developers. The following list describes some of the things I've found useful among the new features. Clean web.config Files Are Back! If you've been using ASP.NET 3.5, you probably have noticed that the web.config file has turned into quite a mess of configuration settings between all the custom handler and module mappings for the various web server versions. Part of the reason for this mess is that .NET 3.5 is a collection of add-on components running on top of the .NET Runtime 2.0 and so almost all of the new features of .NET 3.5 where essentially introduced as custom modules and handlers that had to be explicitly configured in the config file. Because the core runtime didn't rev with 3.5, all those configuration options couldn't be moved up to other configuration files in the system chain. With version 4.0 a consolidation was possible, and the result is a much simpler web.config file by default. A default empty ASP.NET 4.0 Web Forms project looks like this: <?xml version="1.0"?> <configuration> <system.web> <compilation debug="true" targetFramework="4.0" /> </system.web> </configuration> Need I say more? Configuration Transformation Files to Manage Configurations and Application Packaging ASP.NET 4.0 introduces the ability to create multi-target configuration files. This means it's possible to create a single configuration file that can be transformed based on relatively simple replacement rules using a Visual Studio and WebDeploy provided XSLT syntax. The idea is that you can create a 'master' configuration file and then create customized versions of this master configuration file by applying some relatively simplistic search and replace, add or remove logic to specific elements and attributes in the original file. To give you an idea, here's the example code that Visual Studio creates for a default web.Release.config file, which replaces a connection string, removes the debug attribute and replaces the CustomErrors section: <?xml version="1.0"?> <configuration xmlns:xdt="http://schemas.microsoft.com/XML-Document-Transform"> <connectionStrings> <add name="MyDB" connectionString="Data Source=ReleaseSQLServer;Initial Catalog=MyReleaseDB;Integrated Security=True" xdt:Transform="SetAttributes" xdt:Locator="Match(name)"/> </connectionStrings> <system.web> <compilation xdt:Transform="RemoveAttributes(debug)" /> <customErrors defaultRedirect="GenericError.htm" mode="RemoteOnly" xdt:Transform="Replace"> <error statusCode="500" redirect="InternalError.htm"/> </customErrors> </system.web> </configuration> You can see the XSL transform syntax that drives this functionality. Basically, only the elements listed in the override file are matched and updated – all the rest of the original web.config file stays intact. Visual Studio 2010 supports this functionality directly in the project system so it's easy to create and maintain these customized configurations in the project tree. Once you're ready to publish your application, you can then use the Publish <yourWebApplication> option on the Build menu which allows publishing to disk, via FTP or to a Web Server using Web Deploy. You can also create a deployment package as a .zip file which can be used by the WebDeploy tool to configure and install the application. You can manually run the Web Deploy tool or use the IIS Manager to install the package on the server or other machine. You can find out more about WebDeploy and Packaging here: http://tinyurl.com/2anxcje. Improved Routing Routing provides a relatively simple way to create clean URLs with ASP.NET by associating a template URL path and routing it to a specific ASP.NET HttpHandler. Microsoft first introduced routing with ASP.NET MVC and then they integrated routing with a basic implementation in the core ASP.NET engine via a separate ASP.NET routing assembly. In ASP.NET 4.0, the process of using routing functionality gets a bit easier. First, routing is now rolled directly into System.Web, so no extra assembly reference is required in your projects to use routing. The RouteCollection class now includes a MapPageRoute() method that makes it easy to route to any ASP.NET Page requests without first having to implement an IRouteHandler implementation. It would have been nice if this could have been extended to serve *any* handler implementation, but unfortunately for anything but a Page derived handlers you still will have to implement a custom IRouteHandler implementation. ASP.NET Pages now include a RouteData collection that will contain route information. Retrieving route data is now a lot easier by simply using this.RouteData.Values["routeKey"] where the routeKey is the value specified in the route template (i.e., "users/{userId}" would use Values["userId"]). The Page class also has a GetRouteUrl() method that you can use to create URLs with route data values rather than hardcoding the URL: <%= this.GetRouteUrl("users",new { userId="ricks" }) %> You can also use the new Expression syntax using <%$RouteUrl %> to accomplish something similar, which can be easier to embed into Page or MVC View code: <a runat="server" href='<%$RouteUrl:RouteName=user, id=ricks %>'>Visit User</a> Finally, the Response object also includes a new RedirectToRoute() method to build a route url for redirection without hardcoding the URL. Response.RedirectToRoute("users", new { userId = "ricks" }); All of these routines are helpers that have been integrated into the core ASP.NET engine to make it easier to create routes and retrieve route data, which hopefully will result in more people taking advantage of routing in ASP.NET. To find out more about the routing improvements you can check out Dan Maharry's blog which has a couple of nice blog entries on this subject: http://tinyurl.com/37trutj and http://tinyurl.com/39tt5w5. Session State Improvements Session state is an often used and abused feature in ASP.NET and version 4.0 introduces a few enhancements geared towards making session state more efficient and to minimize at least some of the ill effects of overuse. The first improvement affects out of process session state, which is typically used in web farm environments or for sites that store application sensitive data that must survive AppDomain restarts (which in my opinion is just about any application). When using OutOfProc session state, ASP.NET serializes all the data in the session statebag into a blob that gets carried over the network and stored either in the State server or SQL Server via the Session provider. Version 4.0 provides some improvement in this serialization of the session data by offering an enableCompression option on the web.Config <Session> section, which forces the serialized session state to be compressed. Depending on the type of data that is being serialized, this compression can reduce the size of the data travelling over the wire by as much as a third. It works best on string data, but can also reduce the size of binary data. In addition, ASP.NET 4.0 now offers a way to programmatically turn session state on or off as part of the request processing queue. In prior versions, the only way to specify whether session state is available is by implementing a marker interface on the HTTP handler implementation. In ASP.NET 4.0, you can now turn session state on and off programmatically via HttpContext.Current.SetSessionStateBehavior() as part of the ASP.NET module pipeline processing as long as it occurs before the AquireRequestState pipeline event. Output Cache Provider Output caching in ASP.NET has been a very useful but potentially memory intensive feature. The default OutputCache mechanism works through in-memory storage that persists generated output based on various lifetime related parameters. While this works well enough for many intended scenarios, it also can quickly cause runaway memory consumption as the cache fills up and serves many variations of pages on your site. ASP.NET 4.0 introduces a provider model for the OutputCache module so it becomes possible to plug-in custom storage strategies for cached pages. One of the goals also appears to be to consolidate some of the different cache storage mechanisms used in .NET in general to a generic Windows AppFabric framework in the future, so various different mechanisms like OutputCache, the non-Page specific ASP.NET cache and possibly even session state eventually can use the same caching engine for storage of persisted data both in memory and out of process scenarios. For developers, the OutputCache provider feature means that you can now extend caching on your own by implementing a custom Cache provider based on the System.Web.Caching.OutputCacheProvider class. You can find more info on creating an Output Cache provider in Gunnar Peipman's blog at: http://tinyurl.com/2vt6g7l. Response.RedirectPermanent ASP.NET 4.0 includes features to issue a permanent redirect that issues as an HTTP 301 Moved Permanently response rather than the standard 302 Redirect respond. In pre-4.0 versions you had to manually create your permanent redirect by setting the Status and Status code properties – Response.RedirectPermanent() makes this operation more obvious and discoverable. There's also a Response.RedirectToRoutePermanent() which provides permanent redirection of route Urls. Preloading of Applications ASP.NET 4.0 provides a new feature to preload ASP.NET applications on startup, which is meant to provide a more consistent startup experience. If your application has a lengthy startup cycle it can appear very slow to serve data to clients while the application is warming up and loading initial resources. So rather than serve these startup requests slowly in ASP.NET 4.0, you can force the application to initialize itself first before even accepting requests for processing. This feature works only on IIS 7.5 (Windows 7 and Windows Server 2008 R2) and works in combination with IIS. You can set up a worker process in IIS 7.5 to always be running, which starts the Application Pool worker process immediately. ASP.NET 4.0 then allows you to specify site-specific settings by setting the serverAutoStartEnabled on a particular site along with an optional serviceAutoStartProvider class that can be used to receive "startup events" when the application starts up. This event in turn can be used to configure the application and optionally pre-load cache data and other information required by the app on startup.  The configuration settings need to be made in applicationhost.config: <sites> <site name="WebApplication2" id="1"> <application path="/" serviceAutoStartEnabled="true" serviceAutoStartProvider="PreWarmup" /> </site> </sites> <serviceAutoStartProviders> <add name="PreWarmup" type="PreWarmupProvider,MyAssembly" /> </serviceAutoStartProviders> Hooking up a warm up provider is optional so you can omit the provider definition and reference. If you do define it here's what it looks like: public class PreWarmupProvider System.Web.Hosting.IProcessHostPreloadClient { public void Preload(string[] parameters) { // initialization for app } } This code fires and while it's running, ASP.NET/IIS will hold requests from hitting the pipeline. So until this code completes the application will not start taking requests. The idea is that you can perform any pre-loading of resources and cache values so that the first request will be ready to perform at optimal performance level without lag. Runtime Performance Improvements According to Microsoft, there have also been a number of invisible performance improvements in the internals of the ASP.NET runtime that should make ASP.NET 4.0 applications run more efficiently and use less resources. These features come without any change requirements in applications and are virtually transparent, except that you get the benefits by updating to ASP.NET 4.0. Summary The core feature set changes are minimal which continues a tradition of small incremental changes to the ASP.NET runtime. ASP.NET has been proven as a solid platform and I'm actually rather happy to see that most of the effort in this release went into stability, performance and usability improvements rather than a massive amount of new features. The new functionality added in 4.0 is minimal but very useful. A lot of people are still running pure .NET 2.0 applications these days and have stayed off of .NET 3.5 for some time now. I think that version 4.0 with its full .NET runtime rev and assembly and configuration consolidation will make an attractive platform for developers to update to. If you're a Web Forms developer in particular, ASP.NET 4.0 includes a host of new features in the Web Forms engine that are significant enough to warrant a quick move to .NET 4.0. I'll cover those changes in my next column. Until then, I suggest you give ASP.NET 4.0 a spin and see for yourself how the new features can help you out. © Rick Strahl, West Wind Technologies, 2005-2010Posted in ASP.NET  

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  • How to retrieve value from DropDownListFor html helper in ASP>NET MVC2?

    - by Eedoh
    Hello I know there was few similar questions here about DropDownListFor, but neither helped me... I use Entity Framework as ORM in my project. There's EF model called "Stete". Stete has Foreign on EF model called "Drustva" Now I'm trying to make a form for editing the data, for Stete model. I managed to display everything, including Stete.Drustva.Naziv property, but I can't get this last property in my handler method [HttpPost]. It always return 0, no matter what I select in drop down list. Here's the code: DrustvaController: public static IEnumerable<SelectListItem> DrustvaToSelectListItemsById(this KnjigaStetnikaEntities pEntities, int Id) { IEnumerable<Drustva> drustva = (from d in pEntities.Drustva select d).ToList(); return drustva.OrderBy(drustvo => drustvo.Naziv).Select(drustvo => new SelectListItem { Text = drustvo.Naziv, Value = drustvo.Id.ToString(), Selected = (drustvo.Id == Id)? true : false }); } SteteController: private IEnumerable<SelectListItem> privremenaListaDrustava(int Id) { using (var ctx = new KnjigaStetnikaEntities()) { return ctx.DrustvaToSelectListItemsById(Id); } } public ActionResult IzmijeniPodatkeStete(Int32 pBrojStete) { PretragaStetaModel psm = new PretragaStetaModel(); ViewData["drustva"] = privremenaListaDrustava(psm.VratiStetuPoBrojuStete(pBrojStete).Drustva.Id); ViewData.Model = new Models.Stete(); return View("EditView", (Stete.Models.Stete)psm.GetSteta(pBrojStete)); } EditView: <div class="editor-label"> <%: Html.Label("Društvo") %> </div> <div class="editor-field"> <%: Html.DropDownListFor(m => m.Drustva.Naziv, ViewData["drustva"] as IEnumerable<SelectListItem>) %> <%: Html.ValidationMessageFor(model => model.FKDrustvo) %> </div> I am sorry for not translating names of the objects into english, but they hardly have appropriate translation. If necessary, I can try creating similar example...

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  • DRY Validation with MVC2

    - by Matthew
    Hi All, I'm trying to figure out how I can define validation rules for my domain objects in one single location within my application but have run in to a snag... Some background: My location has several parts: - Database - DAL - Business Logic Layer - SOAP API Layer - MVC website The MVC website accesses the database via the SOAP API, just as third parties would. We are using server and and client side validation on the MVC website as well as in the SOAP API Layer. To avoid having to manually write client side validation we are implementing strongly typed views in conjunction with the Html.TextBoxFor and Html.ValidationMessageFor HTML helpers, as shown in Step 3 here. We also create custom models for each form where one form takes input for multiple domain objects. This is where the problem begins, the HTML helpers read from the model for the data annotation validation attributes. In most cases our forms deal with multiple domain objects and you can't specify more than one type in the <%@Page ... Inherits="System.Web.Mvc.ViewPage" % page directive. So we are forced to create a custom model class, which would mean duplicating validation attributes from the domain objects on to the model class. I've spent quite some time looking for workarounds to this, such has referencing the same MetadataType from both the domain class and the custom MVC models, but that won't work for several reasons: You can only specify one MetadataType attribute per class, so its a problem if a model references multiple domain objects, each with their own metadata type. The data annotation validation code throws an exception if the model class doesn't contain a property that is specified in the referenced MetadataType which is a problem with the model only deals with a subset of the properties for a given domain object. I've looked at other solutions as well but to no avail. If anyone has any ideas on how to achieve a single source for validation logic that would work across MVC client and server side validation functionality and other locations (such as my SOAP API) I would love to hear it! Thanks in advance, Matthew

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  • Django 1.2 + South 0.7 + django-annoying's AutoOneToOneField leads to TypeError: 'LegacyConnection'

    - by konrad
    I'm using Django 1.2 trunk with South 0.7 and an AutoOneToOneField copied from django-annoying. South complained that the field does not have rules defined and the new version of South no longer has an automatic field type parser. So I read the South documentation and wrote the following definition (basically an exact copy of the OneToOneField rules): rules = [ ( (AutoOneToOneField), [], { "to": ["rel.to", {}], "to_field": ["rel.field_name", {"default_attr": "rel.to._meta.pk.name"}], "related_name": ["rel.related_name", {"default": None}], "db_index": ["db_index", {"default": True}], }, ) ] from south.modelsinspector import add_introspection_rules add_introspection_rules(rules, ["^myapp"]) Now South raises the following error when I do a schemamigration. Traceback (most recent call last): File "manage.py", line 11, in <module> execute_manager(settings) File "django/core/management/__init__.py", line 438, in execute_manager utility.execute() File "django/core/management/__init__.py", line 379, in execute self.fetch_command(subcommand).run_from_argv(self.argv) File "django/core/management/base.py", line 196, in run_from_argv self.execute(*args, **options.__dict__) File "django/core/management/base.py", line 223, in execute output = self.handle(*args, **options) File "South-0.7-py2.6.egg/south/management/commands/schemamigration.py", line 92, in handle (k, v) for k, v in freezer.freeze_apps([migrations.app_label()]).items() File "South-0.7-py2.6.egg/south/creator/freezer.py", line 33, in freeze_apps model_defs[model_key(model)] = prep_for_freeze(model) File "South-0.7-py2.6.egg/south/creator/freezer.py", line 65, in prep_for_freeze fields = modelsinspector.get_model_fields(model, m2m=True) File "South-0.7-py2.6.egg/south/modelsinspector.py", line 322, in get_model_fields args, kwargs = introspector(field) File "South-0.7-py2.6.egg/south/modelsinspector.py", line 271, in introspector arg_defs, kwarg_defs = matching_details(field) File "South-0.7-py2.6.egg/south/modelsinspector.py", line 187, in matching_details if any([isinstance(field, x) for x in classes]): TypeError: 'LegacyConnection' object is not iterable Is this related to a recent change in Django 1.2 trunk? How do I fix this? I use this field as follows: class Bar(models.Model): foo = AutoOneToOneField("foo.Foo", primary_key=True, related_name="bar") For reference the field code from django-tagging: class AutoSingleRelatedObjectDescriptor(SingleRelatedObjectDescriptor): def __get__(self, instance, instance_type=None): try: return super(AutoSingleRelatedObjectDescriptor, self).__get__(instance, instance_type) except self.related.model.DoesNotExist: obj = self.related.model(**{self.related.field.name: instance}) obj.save() return obj class AutoOneToOneField(OneToOneField): def contribute_to_related_class(self, cls, related): setattr(cls, related.get_accessor_name(), AutoSingleRelatedObjectDescriptor(related))

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  • C#: Delegate syntax?

    - by Rosarch
    I'm developing a game. I want to have game entities each have their own Damage() function. When called, they will calculate how much damage they want to do: public class CombatantGameModel : GameObjectModel { public int Health { get; set; } /// <summary> /// If the attack hits, how much damage does it do? /// </summary> /// <param name="randomSample">A random value from [0 .. 1]. Use to introduce randomness in the attack's damage.</param> /// <returns>The amount of damage the attack does</returns> public delegate int Damage(float randomSample); public CombatantGameModel(GameObjectController controller) : base(controller) {} } public class CombatantGameObject : GameObjectController { private new readonly CombatantGameModel model; public new virtual CombatantGameModel Model { get { return model; } } public CombatantGameObject() { model = new CombatantGameModel(this); } } However, when I try to call that method, I get a compiler error: /// <summary> /// Calculates the results of an attack, and directly updates the GameObjects involved. /// </summary> /// <param name="attacker">The aggressor GameObject</param> /// <param name="victim">The GameObject under assault</param> public void ComputeAttackUpdate(CombatantGameObject attacker, CombatantGameObject victim) { if (worldQuery.IsColliding(attacker, victim, false)) { victim.Model.Health -= attacker.Model.Damage((float) rand.NextDouble()); // error here Debug.WriteLine(String.Format("{0} hits {1} for {2} damage", attacker, victim, attackTraits.Damage)); } } The error is: 'Damage': cannot reference a type through an expression; try 'HWAlphaRelease.GameObject.CombatantGameModel.Damage' instead What am I doing wrong?

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  • How to retrieve value from DropDownListFor html helper in ASP.NET MVC2?

    - by Eedoh
    Hello I know there was few similar questions here about DropDownListFor, but neither helped me... I use Entity Framework as ORM in my project. There's EF model called "Stete". Stete has Foreign on EF model called "Drustva" Now I'm trying to make a form for editing the data, for Stete model. I managed to display everything, including Stete.Drustva.Naziv property, but I can't get this last property in my handler method [HttpPost]. It always return 0, no matter what I select in drop down list. Here's the code: DrustvaController: public static IEnumerable<SelectListItem> DrustvaToSelectListItemsById(this KnjigaStetnikaEntities pEntities, int Id) { IEnumerable<Drustva> drustva = (from d in pEntities.Drustva select d).ToList(); return drustva.OrderBy(drustvo => drustvo.Naziv).Select(drustvo => new SelectListItem { Text = drustvo.Naziv, Value = drustvo.Id.ToString(), Selected = (drustvo.Id == Id)? true : false }); } SteteController: private IEnumerable<SelectListItem> privremenaListaDrustava(int Id) { using (var ctx = new KnjigaStetnikaEntities()) { return ctx.DrustvaToSelectListItemsById(Id); } } public ActionResult IzmijeniPodatkeStete(Int32 pBrojStete) { PretragaStetaModel psm = new PretragaStetaModel(); ViewData["drustva"] = privremenaListaDrustava(psm.VratiStetuPoBrojuStete(pBrojStete).Drustva.Id); ViewData.Model = new Models.Stete(); return View("EditView", (Stete.Models.Stete)psm.GetSteta(pBrojStete)); } EditView: <div class="editor-label"> <%: Html.Label("Društvo") %> </div> <div class="editor-field"> <%: Html.DropDownListFor(m => m.Drustva.Naziv, ViewData["drustva"] as IEnumerable<SelectListItem>) %> <%: Html.ValidationMessageFor(model => model.FKDrustvo) %> </div> I am sorry for not translating names of the objects into english, but they hardly have appropriate translation. If necessary, I can try creating similar example...

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  • ASP.NET MVC Page - hyper links in HTML.ValidationSummary

    - by Rita
    Hi I have Registration page and if the validation fails, it displays the error messages using HTML.ValidationSummary control. Now i have to display the Hyperlink in that Validation Error Message. But it is treating href also as string. The Validation Message that I am trying to display with hyperlink is: **"User already exists in the system, please <a href='../Login.aspx'>login</a>"** Appreciate your responses. Here is my Code: <% using (Html.BeginForm()) {%> <%= Html.ValidationSummary(false) %> <fieldset> <div class="cssform">; <p> <%= Html.LabelFor(model => model.email)%><em>*</em> <%= Html.TextBoxFor(model => model.email, new { @class = "required email" })%> <%= Html.ValidationMessageFor(model => model.email)%> </p> <p> <%= Html.Label("Confirm email")%><em>*</em> <%= Html.TextBox("confirm_email")%> <%= Html.ValidationMessage("confirm_email") %> </p> <p> <%= Html.Label("Password")%><em>*</em> <%= Html.Password("Password", null, new { @class = "required" })%> <%= Html.ValidationMessage("Password")%><br /> (Note: Password should be minimum 6 characters) </p> <p> <%= Html.Label("Confirm Password")%><em>*</em> <%= Html.Password("confirm_password")%> <%= Html.ValidationMessage("confirm_password") %> </p><hr /> <% } %

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  • InvalidCastException for two Objects of the same type

    - by LLEA
    hi, I have this weird problem that I cannot handle myself. A class in the model of my mvp-project designed as singleton causes an InvalidCastException. The source of error is found in this code line where the deserialised object is assigned to the instance variable of the class: engineObject = (ENGINE)xSerializer.Deserialize(str); It occurs whenever I try to add one of my UserControls to a Form or to a different UC. All of my UCs have a special presenter that access the above mentioned instance variable of the singleton class. This is what I get when trying to add a UC somewhere: 'System.TypeInitializationException: The type initializer for 'MVP.Model.EngineData' threw an exception. ---- System.InvalidCastException: [A]Engine cannot be cast to [B]Engine. Type A originates from 'MVP.Model, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null' in the context 'LoadNeither' at location '[...]\AppData\Roaming\Microsoft\VisualStudio\9.0\ProjectAssemblies\uankw1hh01\MVP.Model.dll'. Type B originates from 'MVP.Model, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null' in the context 'LoadNeither' at location '[...]\AppData\Roaming\Microsoft\VisualStudio\9.0\ProjectAssemblies\u_hge2de01\MVP.Model.dll'... So I somehow have two assemblies and they are not accessed from my project folder, but from a VS temp folder? I googled a lot and only found this: IronPython Exception: [A]Person cannot be cast to [B]Person. There is a solution offered, but first it concerns IronPhyton and second I don't know where to use it within my project? It would be just great, if u could help me out here :-) thx

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  • Moq for Silverlight doesn't raise event

    - by Budda
    Trying to write Unit test for Silverlight 4.0 using Moq 4.0.10531.7 public delegate void DataReceived(ObservableCollection<TeamPlayerData> AllReadyPlayers, GetSquadDataCompletedEventArgs squadDetails); public interface ISquadModel : IModelBase { void RequestData(int matchId, int teamId); void SaveData(); event DataReceived DataReceivedEvent; } void MyTest() { Mock<ISquadModel> mockSquadModel = new Mock<ISquadModel>(); mockSquadModel.Raise(model => model.DataReceivedEvent += null, EventArgs.Empty); } Instead of raising the 'DataReceivingEvent' the following error is received: Object of type 'Castle.Proxies.ISquadModelProxy' cannot be converted to type 'System.Collections.ObjectModel.ObservableCollection`1[TeamPlayerData]'. Why attempt to convert mock to the type of 1st event parameter is performed? How can I raise an event? I've also tried another approach: mockSquadModel .Setup(model => model.RequestData(TestMatchId, TestTeamId)) .Raises(model => model.DataReceivedEvent += null, EventArgs.Empty) ; this should raise event if case somebody calls 'Setup' method... Instead the same error is generated... Any thoughts are welcome. Thanks

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  • Custom Django admin URL + changelist view for custom list filter by Tags

    - by Botondus
    In django admin I wanted to set up a custom filter by tags (tags are introduced with django-tagging) I've made the ModelAdmin for this and it used to work fine, by appending custom urlconf and modifying the changelist view. It should work with URLs like: http://127.0.0.1:8000/admin/reviews/review/only-tagged-vista/ But now I get 'invalid literal for int() with base 10: 'only-tagged-vista', error which means it keeps matching the review edit page instead of the custom filter page, and I cannot figure out why since it used to work and I can't find what change might have affected this. Any help appreciated. Relevant code: class ReviewAdmin(VersionAdmin): def changelist_view(self, request, extra_context=None, **kwargs): from django.contrib.admin.views.main import ChangeList cl = ChangeList(request, self.model, list(self.list_display), self.list_display_links, self.list_filter, self.date_hierarchy, self.search_fields, self.list_select_related, self.list_per_page, self.list_editable, self) cl.formset = None if extra_context is None: extra_context = {} if kwargs.get('only_tagged'): tag = kwargs.get('tag') cl.result_list = cl.result_list.filter(tags__icontains=tag) extra_context['extra_filter'] = "Only tagged %s" % tag extra_context['cl'] = cl return super(ReviewAdmin, self).changelist_view(request, extra_context=extra_context) def get_urls(self): from django.conf.urls.defaults import patterns, url urls = super(ReviewAdmin, self).get_urls() def wrap(view): def wrapper(*args, **kwargs): return self.admin_site.admin_view(view)(*args, **kwargs) return update_wrapper(wrapper, view) info = self.model._meta.app_label, self.model._meta.module_name my_urls = patterns('', # make edit work from tagged filter list view # redirect to normal edit view url(r'^only-tagged-\w+/(?P<id>.+)/$', redirect_to, {'url': "/admin/"+self.model._meta.app_label+"/"+self.model._meta.module_name+"/%(id)s"} ), # tagged filter list view url(r'^only-tagged-(P<tag>\w+)/$', self.admin_site.admin_view(self.changelist_view), {'only_tagged':True}, name="changelist_view"), ) return my_urls + urls Edit: Original issue fixed. I now receive 'Cannot filter a query once a slice has been taken.' for line: cl.result_list = cl.result_list.filter(tags__icontains=tag) I'm not sure where this result list is sliced, before tag filter is applied. Edit2: It's because of the self.list_per_page in ChangeList declaration. However didn't find a proper solution yet. Temp fix: if kwargs.get('only_tagged'): list_per_page = 1000000 else: list_per_page = self.list_per_page cl = ChangeList(request, self.model, list(self.list_display), self.list_display_links, self.list_filter, self.date_hierarchy, self.search_fields, self.list_select_related, list_per_page, self.list_editable, self)

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  • Magento install errors

    - by nXqd
    I try to install new magento version 1.4.xx . But after the config menu I meet after I copy and change local.example.xml to local.xml . Error in file: "E:\Soft\Programming\xampp\htdocs\magento\app\code\core\Mage\Catalog\sql\catalog_setup\mysql4-install-1.4.0.0.0.php" - SQLSTATE[23000]: Integrity constraint violation: 1062 Duplicate entry '4-page_layout' for key 'entity_type_id' Trace: #0 E:\Soft\Programming\xampp\htdocs\magento\app\code\core\Mage\Core\Model\Resource\Setup.php(374): Mage::exception('Mage_Core', 'Error in file: ...') #1 E:\Soft\Programming\xampp\htdocs\magento\app\code\core\Mage\Core\Model\Resource\Setup.php(260): Mage_Core_Model_Resource_Setup->_modifyResourceDb('install', '', '1.4.0.0.21') #2 E:\Soft\Programming\xampp\htdocs\magento\app\code\core\Mage\Core\Model\Resource\Setup.php(224): Mage_Core_Model_Resource_Setup->_installResourceDb('1.4.0.0.21') #3 E:\Soft\Programming\xampp\htdocs\magento\app\code\core\Mage\Core\Model\Resource\Setup.php(153): Mage_Core_Model_Resource_Setup->applyUpdates() #4 E:\Soft\Programming\xampp\htdocs\magento\app\code\core\Mage\Core\Model\App.php(363): Mage_Core_Model_Resource_Setup::applyAllUpdates() #5 E:\Soft\Programming\xampp\htdocs\magento\app\code\core\Mage\Core\Model\App.php(295): Mage_Core_Model_App->_initModules() #6 E:\Soft\Programming\xampp\htdocs\magento\app\Mage.php(596): Mage_Core_Model_App->run(Array) #7 E:\Soft\Programming\xampp\htdocs\magento\index.php(78): Mage::run('', 'store') #8 {main} I really need your help , thanks so much :)

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  • JAXB - Beans to XSD or XSD to beans?

    - by bajafresh4life
    I have an existing data model. I would like to express this data model in terms of XML. It looks like I have two options if I'm to use JAXB: Create an XSD that mirrors my data model, and use xjc to create binding objects. Marshalling and unmarshalling will involve creating a "mapping" class that would take my existing data objects and map them to the objects that xjc created. For example, in my data model I have a Doc class, and JAXB would create another Doc class with basically the same exact fields, and I would have to map from my Doc class to xjc's Doc class. Annotate my existing data model with JAXB annotations, and use schemagen to generate an XSD from my annotated classes. I can see advantanges and disadvantages of both approaches. It seems that most people using JAXB start with the XSD file. It makes sense that the XSD should be the gold standard truth, since it expresses the data model in a truly cross-platform way. I'm inclined to start with the XSD first, but it seems icky that I have to write and maintain a separate mapping class that shuttles data in between my world and JAXB world. Any recommendations?

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  • Optimized Publish/Subcribe JMS Broker Cluster and Conflicting Posts on StackOverFlow for the Answer

    - by Gene
    Hi, I am looking to build a publish/subscribe distributed messaging framework that can manage huge volumes of message traffic with some intelligence at the broker level. I don't know if there's a topology that describes this, but this is the model I'm going after: EXAMPLE MODEL A A) There are two running message brokers (ideally all on localhost if possible, for easier demo-ing) : Broker-A Broker-B B) Each broker will have 2 listeners and 1 publisher. Example Figure [subscriber A1, subscriber A2, publisher A1] <-- BrokerA <-- BrokerB <-- [publisher B1, subscriber B1, subscriber B2] IF a message-X is published to broker A and there no subscribers for it among the listeners on Broker-B (via criteria in Message Selectors or Broker routing rules), then that message-X will never be published to Broker-B. ELSE, broker A will publish the message to broker B, where one of the broker B listeners/subscribers/services is expecting that message based on the subscription criteria. Is Clustering the Correct Approach? At first, I concluded that the "Broker Clustering" concept is what I needed to support this. However, as I have come to understand it, the typical use of clustering entails either: message redundancy across all brokers ... or Competing Consumers pattern ... and neither of these satisfy the requirement in the EXAMPLE MODEL A. What is the Correct Approach? My question is, does anyone know of a JMS implementation that supports the model I described? I scanned through all the stackoverflow post titles for the search: JMS and Cluster. I found these two informative, but seemingly conflicting posts: Says the EXAMPLE MODEL A is/should-be implicitly supported: http://stackoverflow.com/questions/2255816/jms-consumer-with-activemq-network-of-brokers " this means you pick a broker, connect to it, and let the broker network sort it out amongst themselves. In theory." Says the EXAMPLE MODEL A IS NOT suported: http://stackoverflow.com/questions/2017520/how-does-a-jms-topic-subscriber-in-a-clustered-application-server-recieve-message "All the instances of PropertiesSubscriber running on different app servers WILL get that message." Any suggestions would be greatly appreciated. Thanks very much for reading my post, Gene

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  • Should I have different models and views for no user data than for some user data?

    - by Sam Holder
    I'm just starting to learn asp.net mvc and I'm not sure what the right thing to do is. I have a user and a user has a collection of (0 or more) reminders. I have a controller for the user which gets the reminders for the currently logged in user from a reminder service. It populates a model which holds some information about the user and the collection of reminders. My question is should I have 2 different views, one for when there are no reminders and one for when there are some reminders? Or should I have 1 view which checks the number of reminders and displays different things? Having one view seems wrong as then I end up with code in my view which says if (Model.Reminders.Count==0){//do something} else {do something else}, and having logic in the view feels wrong. But if I want to have 2 different views then I'd like to have some code like this in my controller: [Authorize] public ActionResult Index() { MembershipUser currentUser = m_membershipService.GetUser(); IList<Reminder> reminders = m_reminderRepository.GetReminders(currentUser); if (reminders.Count == 0) { var model = new EmptyReminderModel { Email = currentUser.Email, UserName = currentUser.UserName }; return View(model); } else { var model = new ReminderModel { Email = currentUser.Email, UserName = currentUser.UserName, Reminders = reminders }; return View(model); } but obviously this doesn't compile as the View can't take both different types. So if I'm going to do this should I return a specific named view from my controller, depending on the emptiness of the reminders, or should my Index() method redirect to other actions like so: [Authorize] public ActionResult Index() { MembershipUser currentUser = m_membershipService.GetUser(); IList<Reminder> reminders = m_reminderRepository.GetReminders(currentUser); if (reminders.Count == 0) { return RedirectToAction("ShowEmptyReminders"); } else { return RedirectToAction("ShowReminders"); } } which seems nicer but then I need to re-query the reminders for the current user in the ShowReminders action. Or should I be doing something else entirely?

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  • Django's post_save signal behaves weirdly with models using multi-table inheritance

    - by hekevintran
    Django's post_save signal behaves weirdly with models using multi-table inheritance I am noticing an odd behavior in the way Django's post_save signal works when using a model that has multi-table inheritance. I have these two models: class Animal(models.Model): category = models.CharField(max_length=20) class Dog(Animal): color = models.CharField(max_length=10) I have a post save callback called echo_category: def echo_category(sender, **kwargs): print "category: '%s'" % kwargs['instance'].category post_save.connect(echo_category, sender=Dog) I have this fixture: [ { "pk": 1, "model": "animal.animal", "fields": { "category": "omnivore" } }, { "pk": 1, "model": "animal.dog", "fields": { "color": "brown" } } ] In every part of the program except for in the post_save callback the following is true: from animal.models import Dog Dog.objects.get(pk=1).category == u'omnivore' # True When I run syncdb and the fixture is installed, the echo_category function is run. The output from syncdb is: $ python manage.py syncdb --noinput Installing json fixture 'initial_data' from '~/my_proj/animal/fixtures'. category: '' Installed 2 object(s) from 1 fixture(s) The weird thing here is that the dog object's category attribute is an empty string. Why is it not 'omnivore' like it is everywhere else? As a temporary (hopefully) workaround I reload the object from the database in the post_save callback: def echo_category(sender, **kwargs): instance = kwargs['instance'] instance = sender.objects.get(pk=instance.pk) print "category: '%s'" % instance.category post_save.connect(echo_category, sender=Dog) This works but it is not something I like because I must remember to do it when the model inherits from another model and it must hit the database again. The other weird thing is that I must do instance.pk to get the primary key. The normal 'id' attribute does not work (I cannot use instance.id). I do not know why this is. Maybe this is related to the reason why the category attribute is not doing the right thing?

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  • getting proxies of the correct type in nhibernate

    - by Nir
    I have a problem with uninitialized proxies in nhibernate The Domain Model Let's say I have two parallel class hierarchies: Animal, Dog, Cat and AnimalOwner, DogOwner, CatOwner where Dog and Cat both inherit from Animal and DogOwner and CatOwner both inherit from AnimalOwner. AnimalOwner has a reference of type Animal called OwnedAnimal. Here are the classes in the example: public abstract class Animal { // some properties } public class Dog : Animal { // some more properties } public class Cat : Animal { // some more properties } public class AnimalOwner { public virtual Animal OwnedAnimal {get;set;} // more properties... } public class DogOwner : AnimalOwner { // even more properties } public class CatOwner : AnimalOwner { // even more properties } The classes have proper nhibernate mapping, all properties are persistent and everything that can be lazy loaded is lazy loaded. The application business logic only let you to set a Dog in a DogOwner and a Cat in a CatOwner. The Problem I have code like this: public void ProcessDogOwner(DogOwner owner) { Dog dog = (Dog)owner.OwnedAnimal; .... } This method can be called by many diffrent methods, in most cases the dog is already in memory and everything is ok, but rarely the dog isn't already in memory - in this case I get an nhibernate "uninitialized proxy" but the cast throws an exception because nhibernate genrates a proxy for Animal and not for Dog. I understand that this is how nhibernate works, but I need to know the type without loading the object - or, more correctly I need the uninitialized proxy to be a proxy of Cat or Dog and not a proxy of Animal. Constraints I can't change the domain model, the model is handed to me by another department, I tried to get them to change the model and failed. The actual model is much more complicated then the example and the classes have many references between them, using eager loading or adding joins to the queries is out of the question for performance reasons. I have full control of the source code, the hbm mapping and the database schema and I can change them any way I want (as long as I don't change the relationships between the model classes). I have many methods like the one in the example and I don't want to modify all of them. Thanks, Nir

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  • Syncing data between devel/live databases in Django

    - by T. Stone
    With Django's new multi-db functionality in the development version, I've been trying to work on creating a management command that let's me synchronize the data from the live site down to a developer machine for extended testing. (Having actual data, particularly user-entered data, allows me to test a broader range of inputs.) Right now I've got a "mostly" working command. It can sync "simple" model data but the problem I'm having is that it ignores ManyToMany fields which I don't see any reason for it do so. Anyone have any ideas of either how to fix that or a better want to handle this? Should I be exporting that first query to a fixture first and then re-importing it? from django.core.management.base import LabelCommand from django.db.utils import IntegrityError from django.db import models from django.conf import settings LIVE_DATABASE_KEY = 'live' class Command(LabelCommand): help = ("Synchronizes the data between the local machine and the live server") args = "APP_NAME" label = 'application name' requires_model_validation = False can_import_settings = True def handle_label(self, label, **options): # Make sure we're running the command on a developer machine and that we've got the right settings db_settings = getattr(settings, 'DATABASES', {}) if not LIVE_DATABASE_KEY in db_settings: print 'Could not find "%s" in database settings.' % LIVE_DATABASE_KEY return if db_settings.get('default') == db_settings.get(LIVE_DATABASE_KEY): print 'Data cannot synchronize with self. This command must be run on a non-production server.' return # Fetch all models for the given app try: app = models.get_app(label) app_models = models.get_models(app) except: print "The app '%s' could not be found or models could not be loaded for it." % label for model in app_models: print 'Syncing %s.%s ...' % (model._meta.app_label, model._meta.object_name) # Query each model from the live site qs = model.objects.all().using(LIVE_DATABASE_KEY) # ...and save it to the local database for record in qs: try: record.save(using='default') except IntegrityError: # Skip as the record probably already exists pass

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  • Castle Active Record - Working with the cache

    - by David
    Hi All, im new to the Castle Active Record Pattern and Im trying to get my head around how to effectivley use cache. So what im trying to do (or want to do) is when calling the GetAll, find out if I have called it before and check the cache, else load it, but I also want to pass a bool paramter that will force the cache to clear and requery the db. So Im just looking for the final bits. thanks public static List<Model.Resource> GetAll(bool forceReload) { List<Model.Resource> resources = new List<Model.Resource>(); //Request to force reload if (forceReload) { //need to specify to force a reload (how?) XmlConfigurationSource source = new XmlConfigurationSource("appconfig.xml"); ActiveRecordStarter.Initialize(source, typeof(Model.Resource)); resources = Model.Resource.FindAll().ToList(); } else { //Check the cache somehow and return the cache? } return resources; } public static List<Model.Resource> GetAll() { return GetAll(false); }

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  • GRID is not properly rendered in ExtJS 4 by using Store

    - by user548543
    Here is the Src code for HTML file <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4 /strict.dtd"> <html> <head> <title>MVC Architecture</title> <link rel="stylesheet" type="text/css" href="/bh/extjs/resources/css/ext-all.css" /> <script type="text/javascript" src="extjs/ext-debug.js"></script> <script type="text/javascript" src="Main.js"></script> </head> <body> </body> </html> File path: /bh/Main.js [Main File] Ext.require('Ext.container.Viewport'); Ext.application({ name: 'App', appFolder: 'app', controllers: ['UserController'], launch: function() { Ext.create('Ext.container.Viewport', { layout: 'border', items: [ { xtype: 'userList' } ] }); } }); File path: /app/controller/UserController.js [Controller] Ext.define('App.controller.UserController',{ extend: 'Ext.app.Controller', stores: ['UserStore'], models:['UserModel'], views:['user.UserList'], init: function() { this.getUserStoreStore().load(); } }); File path: /app/store/UserStore.js Ext.define('App.store.UserStore', { extend: 'Ext.data.Store', model: 'App.model.UserModel', proxy: { type: 'ajax', url: 'app/data/contact.json' } }); File path: /app/model/UserModel.js [Model] Ext.define('App.model.UserModel',{ extends:'Ext.data.Model', fields:[ {name: 'name', type: 'string'}, {name: 'age', type: 'string'}, {name: 'phone', type: 'string'}, {name: 'email', type: 'string'} ] }); File path: /app/view/UserList.js [View] Ext.define('App.view.user.UserList' ,{ extend: 'Ext.grid.Panel', alias:'widget.userList', title:'Contacts', region:'center', resizable:true, initComponent: function() { this.store = 'UserStore'; this.columns = [ {text: 'Name',flex:1,sortable: true,dataIndex: 'name'}, {text: 'Age',flex:1,sortable: true,dataIndex: 'age'}, {text: 'Phone',flex:1,sortable: true,dataIndex: 'phone'}, {text: 'Email',flex:1,sortable: true,dataIndex: 'email'} ]; this.callParent(arguments); } }); In fire bug it shows the JSON response as follows: [{ "name": "Aswini", "age": "32", "phone": "555-555-5555", "email": "[email protected]" }] Why the Data has not been displayed although I have a valid json response. Please help!!!

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  • Django: Save data from form in DB

    - by Anry
    I have a model: class Cost(models.Model): project = models.ForeignKey(Project) cost = models.FloatField() date = models.DateField() For the model I created a class form: class CostForm(ModelForm): class Meta: model = Cost fields = ['date', 'cost'] view.py: def cost(request, offset): if request.method == 'POST': #HOW save data in DB? return HttpResponseRedirect('/') else: form = CostForm() In the template file determined: <form action="/cost/{{ project }}/" method="post" accept-charset="utf-8"> <label for="date">Date:</label><input type="text" name="date" value={{ current_date }} id="date" /> <label for="cost">Cost:</label><input type="text" name="cost" value="0" id="cost" /> <p><input type="submit" value="Add"></p> </form> How save data from form in DB? P.S. offset = project name Model: class Project(models.Model): title = models.CharField(max_length=150) url = models.URLField() manager = models.ForeignKey(User) timestamp = models.DateTimeField() I tried to write: def cost(request, offset): if request.method == 'POST': form = CostForm(request.POST) if form.is_valid(): instance = form.save(commit=False) instance.project = Project.objects.filter(title=offset) instance.date = request.date instance.cost = request.cost instance.save() return HttpResponseRedirect('/') else: form = CostForm() But it does not work :(

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  • View Models (ViewData), UserControls/Partials and Global variables - best practice?

    - by elado
    Hi I'm trying to figure out a good way to have 'global' members (such as CurrentUser, Theme etc.) in all of my partials as well as in my views. I don't want to have a logic class that can return this data (like BL.CurrentUser) I do think it needs to be a part of the Model in my views So I tried inheriting from BaseViewData with these members. In my controllers, in this way or another (a filter or base method in my BaseController), I create an instance of the inheriting class and pass it as a view data. Everything's perfect till this point, cause then I have my view data available on the main View with the base members. But what about partials? If I have a simple partial that needs to display a blog post then it looks like this: <%@ Control Language="C#" AutoEventWireup="true" Inherits="ViewUserControl<Post>" %> and simple code to render this partial in my view (that its model.Posts is IEnumerable<Post>): <%foreach (Post p in this.Model.Posts) {%> <%Html.RenderPartial("Post",p); %> <%}%> Since the partial's Model isn't BaseViewData, I don't have access to those properties. Hence, I tried to make a class named PostViewData which inherits from BaseViewData, but then my containing views will have a code to actually create the PostViewData in them in order to pass it to the partial: <%Html.RenderPartial("Post",new PostViewData { Post=p,CurrentUser=Model.CurrentUser,... }); %> Or I could use a copy constructor <%Html.RenderPartial("Post",new PostViewData(Model) { Post=p }); %> I just wonder if there's any other way to implement this before I move on. Any suggestions? Thanks!

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