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  • Advantages and disadvantages of building a single page web application

    - by ryanzec
    I'm nearing the end of a prototyping/proof of concept phase for a side project I'm working on, and trying to decide on some larger scale application design decisions. The app is a project management system tailored more towards the agile development process. One of the decisions I need to make is whether or not to go with a traditional multi-page application or a single page application. Currently my prototype is a traditional multi-page setup, however I have been looking at backbone.js to clean up and apply some structure to my Javascript (jQuery) code. It seems like while backbone.js can be used in multi-page applications, it shines more with single page applications. I am trying to come up with a list of advantages and disadvantages of using a single page application design approach. So far I have: Advantages All data has to be available via some sort of API - this is a big advantage for my use case as I want to have an API to my application anyway. Right now about 60-70% of my calls to get/update data are done through a REST API. Doing a single page application will allow me to better test my REST API since the application itself will use it. It also means that as the application grows, the API itself will grow since that is what the application uses; no need to maintain the API as an add-on to the application. More responsive application - since all data loaded after the initial page is kept to a minimum and transmitted in a compact format (like JSON), data requests should generally be faster, and the server will do slightly less processing. Disadvantages Duplication of code - for example, model code. I am going to have to create models both on the server side (PHP in this case) and the client side in Javascript. Business logic in Javascript - I can't give any concrete examples on why this would be bad but it just doesn't feel right to me having business logic in Javascript that anyone can read. Javascript memory leaks - since the page never reloads, Javascript memory leaks can happen, and I would not even know where to begin to debug them. There are also other things that are kind of double edged swords. For example, with single page applications, the data processed for each request can be a lot less since the application will be asking for the minimum data it needs for the particular request, however it also means that there could be a lot more small request to the server. I'm not sure if that is a good or bad thing. What are some of the advantages and disadvantages of single page web applications that I should keep in mind when deciding which way I should go for my project?

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  • OnSelectedIndexChange only fires on second click when using custom page validation script

    - by Kris P
    Okay.. this is hard to explain, so here it goes. I have an update panel which contains a number of controls. The update panel is triggered by the OnSelectedIndexChanged event of a dropdownlist called: ddlUSCitizenshipStatus. It works as expected when I selected a new item. However, if I leave ddlUSCitizenshipStatus with the default value, and then click "submit" button on the page, the requiredfieldvalidators say there is an error on ddlUSCitizenshipStatus (which it should, as I never selected a value). So I then choose a value, the error message goes away on ddlUSCitizenshipStatus, however the updatepanel does not refresh. I've debugged this locally and the OnSelectedIndexChanged event for ddlUSCitizenshipStatus does not fire. If I choose an item in the ddlUSCitizenshipStatus list a second time, the OnSelectedIndexChanged server event fires and the update panel refreshes and works as expected. The issue is, I have to select an item in ddlUSCitizenshipStatus twice, after failed validation, before the updatepanel it's sitting in updates. The submit button on the page looks like this: <asp:LinkButton ID="btnSubmitPage1" runat="server" CssClass="continueButton" OnClick="btnSubmitPage1_Click" CausesValidation="true" OnClientClick="javascript: return ValidatePage();" /> If I remove my custom OnClientClick script, making the submit button look like this: <asp:LinkButton ID="btnSubmitPage1" runat="server" CssClass="continueButton" OnClick="btnSubmitPage1_Click" CausesValidation="true" ValidationGroup="valGrpAdditionalInformation" /> The dropdownlist, update panel, and reguiredfieldvalidator all work as expected. However, I need to run that custom "ValidatePage()" script when the button is clicked. Below is what my ValidatePage script looks like. I've been troubleshooting this for more hours than I can count.... I hope someone is able to help me. Please let me know if you can figure out why ddlUSCitizenshipStatus doesn't update the updatepanel until the second click after a failed validation. function ValidatePage() { var blnDoPostBack = true; if (typeof(Page_ClientValidate) == 'function' ) { //Client side validation can occur, so lets do it. //Validate each validation group. for( var i = 0; i < Page_ValidationSummaries.length; i++ ) Page_ClientValidate( Page_ValidationSummaries[i].validationGroup.toString() ); //Validate every validation control on the page. for (var i = 0; i < Page_Validators.length; i++) ValidatorValidate(Page_Validators[i]); //Figure out which validation groups have errors, store a list of these validation groups in an array. var aryValGrpsWithErrors = []; for( var i = 0; i < Page_Validators.length; i++ ) { if( !Page_Validators[i].isvalid ) { //This particular validator has thrown an error. //Remeber to not do a postback, as we were able to catch this validation error client side. blnDoPostBack = false; //If we haven't already registered the validation group this erroring validation control is a part of, do so now. if( aryValGrpsWithErrors.indexOf( Page_Validators[i].validationGroup.toString() ) == -1 ) aryValGrpsWithErrors[aryValGrpsWithErrors.length++] = Page_Validators[i].validationGroup.toString(); } } //Now display every validation summary that has !isvalid validation controls in it. for( var i = 0; i < Page_ValidationSummaries.length; i++ ) { if( aryValGrpsWithErrors.indexOf( Page_ValidationSummaries[i].validationGroup.toString() ) != -1 ) { Page_ValidationSummaries[i].style.display = ""; document.getElementById( Page_ValidationSummaries[i].id.toString() + "Wrapper" ).style.display = ""; } else { //The current validation summary does not have any error messages in it, so make sure it's hidden. Page_ValidationSummaries[i].style.display = "none"; document.getElementById( Page_ValidationSummaries[i].id.toString() + "Wrapper" ).style.display = "none"; } } } return blnDoPostBack; }

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  • Excel 2010 data validation warning (compatibility mode)

    - by Madmanguruman
    We have some legacy worksheets that were created in Excel 2003, which are used by LabVIEW-based test automation software. The current LabVIEW software can only handle the legacy .xls format, so we're forced to keep these worksheets as-is for the time being. We've migrated to Office 2010 and when working with these worksheets, I see this warning: "The following features in this workbook are not supported by earlier versions of Excel. These features may be lost or degraded when you save this workbook in the currently selected file format. Click Continue to save the workbook anyway. To keep all of your features, click Cancel and then save the file in one of the new file formats." "Significant loss of functionality" "One or more cells in this workbook contain data validation rules which refer to values on other worksheets. These data validation rules will not be saved." When I click 'Find', some cells that do indeed have validation rules are highlighted, but those rules are all on the same worksheet! We're using simple list-based validation, with some cells off to the side containing the valid values (for example, cell B4 has a List with Source "=$D$4:$E$4") This makes no sense to me whatsoever. One, the workbook was created in Excel 2003, so obviously we couldn't implement a feature that doesn't exist. Secondly, the modifications we're making don't involve changing the validation rules at all. Thirdly, the complaint that Excel is making is incorrect! All of the rules are on the same worksheet as the target. As if the story wasn't bizarre enough: I went ahead and saved the worksheet with Excel 2010. I then went to an old computer back in the lab and opened the document with Excel 2003. Guess what - the validations were untouched! My questions are: is this a legitimate bug in Excel 2010, or is this some exotic error in the legacy .xls worksheet that is confusing the heck out of Excel 2010? Has anyone else observed this issue working in compatibility mode?

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  • Performing both client side and server side validation using jQuery and CodeIgniter

    - by Vasu
    What is the right way of doing both client side and server side validation using jQuery and CodeIgniter? I am using the jQuery form plugin for form submit. I would like to use jQuery validation plugin (http://docs.jquery.com/Plugins/Validation) for client side validation and CodeIgniter form validation on the server side. However the two don't seem to gel together (or I am unable to get my head around it). Can someone help please? Whether its a client side validation or server side validation, the user should see consistent UI displaying error messages next to the input fields.

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  • For an ORM supporting data validation, should constraints be enforced in the database as well?

    - by Ramnique Singh
    I have always applied constraints at the database level in addition to my (ActiveRecord) models. But I've been wondering if this is really required? A little background I recently had to unit test a basic automated timestamp generation method for a model. Normally, the test would create an instance of the model and save it without validation. But there are other required fields that aren't nullable at the in the table definition, meaning I cant save the instance even if I skip the ActiveRecord validation. So I'm thinking if I should remove such constraints from the db itself, and let the ORM handle them? Possible advantages if I skip constraints in db, imo - Can modify a validation rule in the model, without having to migrate the database. Can skip validation in testing. Possible disadvantage? If its possible that ORM validation fails or is bypassed, howsoever, the database does not check for constraints. What do you think? EDIT In this case, I'm using the Yii Framework, which generates the model from the database, hence database rules are generated also (though I could always write them post-generation myself too).

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  • Play Framework custom validation errors with multiple String parameters

    - by Mark
    I'm trying to set a custom validation error with multiple params in Play!, but it seems like my validation parameters are not rendered correctly. I have defined in messages: validation.customerror=This is first param "%s", and this is the second "%s" The in my code I execute: validation.addError("","validation.customerror", "FIRST", "SECOND"); And I get: This is first param "", and this is the second "FIRST" Thoughts?

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  • How to perform duplicate key validation using entlib (or DataAnnotations), MVC, and Repository pattern

    - by olivehour
    I have a set of ASP.NET 4 projects that culminate in an MVC (3 RC2) app. The solution uses Unity and EntLib Validation for cross-cutting dependency injection and validation. Both are working great for injecting repository and service layer implementations. However, I can't figure out how to do duplicate key validation. For example, when a user registers, we want to make sure they don't pick a UserID that someone else is already using. For this type of validation, the validating object must have a repository reference... or some other way to get an IQueryable / IEnumerable reference to check against other rows already in the DB. What I have is a UserMetadata class that has all of the property setters and getters for a user, along with all of the appropriate DataAnnotations and EntLib Validation attributes. There is also a UserEntity class implemented using EF4 POCO Entity Generator templates. The UserEntity depends on UserMetadata, because it has a MetadataTypeAttribute. I also have a UserViewModel class that has the same exact MetadataType attribute. This way, I can apply the same validation rules, via attributes, to both the entity and viewmodel. There are no concrete references to the Repository classes whatsoever. All repositories are injected using Unity. There is also a service layer that gets dependency injection. In the MVC project, service layer implementation classes are injected into the Controller classes (the controller classes only contain service layer interface references). Unity then injects the Repository implementations into the service layer classes (service classes also only contain interface references). I've experimented with the DataAnnotations CustomValidationAttribute in the metadata class. The problem with this is the validation method must be static, and the method cannot instantiate a repository implementation directly. My repository interface is IRepository, and I have only one single repository implementation class defined as EntityRepository for all domain objects. To instantiate a repository explicitly I would need to say new EntityRepository(), which would result in a circular dependency graph: UserMetadata [depends on] DuplicateUserIDValidator [depends on] UserEntity [depends on] UserMetadata. I've also tried creating a custom EntLib Validator along with a custom validation attribute. Here I don't have the same problem with a static method. I think I could get this to work if I could just figure out how to make Unity inject my EntityRepository into the validator class... which I can't. Right now, all of the validation code is in my Metadata class library, since that's where the custom validation attribute would go. Any ideas on how to perform validations that need to check against the current repository state? Can Unity be used to inject a dependency into a lower-layer class library?

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  • Effective Data Validation

    - by John Conde
    What's an effective way to handle data validation, say, from a form submission? Originally I had a bunch of if statements that checked each value and collected invalid values in an array for later retrieval (and listing). // Store errors here $errors = array(); // Hypothetical check if a string is alphanumeric if (!preg_match('/^[a-z\d]+$/i', $fieldvalue)) { $errors[$fieldname] = 'Please only use letters and numbers for your street address'; } // etc... What I did next was create a class that handles various data validation scenarios and store the results in an internal array. After data validation was complete I would check to see if any errors occurred and handle accordingly: class Validation { private $errorList = array(); public function isAlphaNumeric($string, $field, $msg = '') { if (!preg_match('/^[a-z\d]+$/i', $string)) { $this->errorList[$field] = $msg; } } // more methods here public function creditCard($cardNumber, $field, $msg = '') { // Validate credit card number } // more methods here public function hasErrors() { return count($this->errorList); } } /* Client code */ $validate = new Validation(); $validate->isAlphaNumeric($fieldvalue1, $fieldname1, 'Please only use letters and numbers for your street address'); $validate->creditCard($fieldvalue2, $fieldname2, 'Please enter a valid credit card number'); if ($validate->hasErrors()) { // Handle as appropriate } Naturally it didn't take long before this class became bloated with the virtually unlimited types of data to be validated. What I'm doing now is using decorators to separate the different types of data into their own classes and call them only when needed leaving generic validations (i.e. isAlphaNumeric()) in the base class: class Validation { private $errorList = array(); public function isAlphaNumeric($string, $field, $msg = '') { if (!preg_match('/^[a-z\d]+$/i', $string)) { $this->errorList[$field] = $msg; } } // more generic methods here public function setError($field, $msg = '') { $this->errorList[$field] = $msg; } public function hasErrors() { return count($this->errorList); } } class ValidationCreditCard { protected $validate; public function __construct(Validation $validate) { $this->validate = $validate; } public function creditCard($cardNumber, $field, $msg = '') { // Do validation // ... // if there is an error $this->validate->setError($field, $msg); } // more methods here } /* Client code */ $validate = new Validation(); $validate->isAlphaNumeric($fieldvalue, $fieldname, 'Please only use letters and numbers for your street address'); $validateCC = new ValidationCreditCard($validate); $validateCC->creditCard($fieldvalue2, $fieldname2, 'Please enter a valid credit card number'); if ($validate->hasErrors()) { // Handle as appropriate } Am I on the right track? Or did I just complicate data validation more then I needed to?

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  • Is Form validation and Business validation too much?

    - by Robert Cabri
    I've got this question about form validation and business validation. I see a lot of frameworks that use some sort of form validation library. You submit some values and the library validates the values from the form. If not ok it will show some errors on you screen. If all goes to plan the values will be set into domain objects. Here the values will be or, better said, should validated (again). Most likely the same validation in the validation library. I know 2 PHP frameworks having this kind of construction Zend/Kohana. When I look at programming and some principles like Don't Repeat Yourself (DRY) and single responsibility principle (SRP) this isn't a good way. As you can see it validates twice. Why not create domain objects that do the actual validation. Example: Form with username and email form is submitted. Values of the username field and the email field will be populated in 2 different Domain objects: Username and Email class Username {} class Email {} These objects validate their data and if not valid throw an exception. Do you agree? What do you think about this aproach? Is there a better way to implement validations? I'm confused about a lot of frameworks/developers handling this stuff. Are they all wrong or am I missing a point? Edit: I know there should also be client side kind of validation. This is a different ballgame in my Opinion. If You have some comments on this and a way to deal with this kind of stuff, please provide.

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  • How stable are Single Page Application (SPA) build with Microsoft .Net for enterprise application [on hold]

    - by Husrat Mehmood
    Imagine a situation where you have your data loading to your application via REST Api,you are building a responsive application(ajax request) for an Enterprise. What potential problems might I run into for a single page application(SPA) using Microsoft Asp.Net Web application build using MVC template? Are there advantages to just designing a multi-page application using asp.net mvc 5 remember I am using SPA for an Enterprise Application where there are role based views for the users.?

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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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  • Create combined client side and server side validation in Symfony2

    - by ausi
    I think it would be very useful to create client side form validation up on the symfony2 Form and Validator components. The best way to do this would be to pass the validation constraints to the form view. With that information it would be possible to make a template that renders a form field to something like this: <div> <label for="form_email">E-Mail</label> <input id="form_email" type="text" name="form[email]" value="" data-validation-constraints='["NotBlank":{},"MinLength":{"limit":6}]' /> </div> The JavaScript part then would be to find all <input> elements that have the data-validation-constraints attribute and create the correct validation for them. To pass the validation constraints to the form view i thought the best way would be to create a form type extension. That's the point of my Question: Is this the correct way? And how is this possible? At the Moment my form type extension looks like this: use Symfony\Component\Form\FormInterface; use Symfony\Component\Form\FormView; use Symfony\Component\Form\FormBuilder; class FieldTypeExtension extends \Symfony\Component\Form\AbstractTypeExtension{ public function getExtendedType(){ return 'field'; } public function buildView(FormView $view, FormInterface $form) { // at this point i didn't find a way to get the // validation constraints out of the $form // the `getAllValidationConstraints` here is just an example $view->set('validation_constraints', $form->getAllValidationConstraints()); } } How can i get all validation constraints applied to one form field out of the FormInterface object?

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  • Define "Validation in the Model"

    - by sunwukung
    There have been a couple of discussions regarding the location of user input validation: http://stackoverflow.com/questions/659950/should-validation-be-done-in-form-objects-or-the-model http://stackoverflow.com/questions/134388/where-do-you-do-your-validation-model-controller-or-view These discussions were quite old, so I wanted to ask the question again to see if anyone had any fresh input. If not, I apologise in advance. If you come from the Validation in the Model camp - does Model mean OOP representation of data (i.e. Active Record/Data Mapper) as "Entity" (to borrow the DDD terminology) - in which case you would, I assume, want all Model classes to inherit common validation constraints. Or can these rules simply be part of a Service in the Model - i.e. a Validation service? For example, could you consider Zend_Form and it's validation classes part of the Model? The concept of a Domain Model does not appear to be limited to Entities, and so validation may not necessarily need to be confined to this Entities. It seems that you would require a lot of potentially superfluous handing of values and responses back and forth between forms and "Entities" - and in some instances you may not persist the data recieved from user input, or recieve it from user input at all.

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  • ASP.NET MVC 2 validation using DTOs instead of domain entities

    - by Kevin Pang
    I'm struggling to mesh two best practices together: Using DataAnnotations + ModelBinding for validation in ASP.NET MVC 2 Using DTOs instead of domain entities when passing data via the ViewModel If I want to pass over DTOs instead of domain entities, then leveraging DataAnnotations + ModelBinding for validation would require me to specify validation attributes on my DTO classes. This results in a lot of duplicated work since multiple DTOs may hold overlapping fields with the same validation restrictions. This means that any time I change a validation rule in my domain, I have to go find all DTOs that correspond with that value and update their validation attributes.

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  • WPF Validation with ContentPresenter

    - by Chris
    Hi, I have a WPF user control which needs to validate some fields. It is bound to a class implementing IDataErrorInfo. When I set the user control as the content of my ContentPresenter in another, already open, window, I can see validation occurring, and error messages being returned, however, I don't get any validation adorner - e.g. the default red outline. If I enter the field and leave it (triggering re-validation) the validation adorner appears. Also, if I show the user control in it's own window it shows the validation adorner immediately. (I'm using Caliburn IResults to do this underneath, e.g. Show.Dialog<VM>(); but I suspect this isn't related) Can anyone offer any suggestion why the validation adorners aren't appearing immediately. (I had guessed animation on my ContentPresenter ContentChanged, however, I have removed this and still experience the problem. thanks, Chris

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  • What to choose API based server or Socket based server for data driven application

    - by Imdad
    I am working on a project which has a Desktop Application for MAC/COCOA, a native application for iPhone another native application in iPad. All the application do almost same thing. The applications are data driven applications. Every communication to server is made via a restful API developed in PHP. When a user logs in a lot of data is fetched from server. And to remain in sync with server pooling is done. As there are lot of data to pool it makes application slower and un-reliable. A possible solution that comes into my mind is to use Socket based server. My question is that will it reasonably improve the performance? And which technology (of sockets) will be good as a server side solution for data driven application? I have heard a lot about Node.js. Please give your suggestions.

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  • Is there a way to validates_presence_of only one time? (to skip that validation once the user's been

    - by GoodGets
    So, I'd like for a user to see an error message if he submits a comment and the :name is blank (typical error message, don't need help with that). However, I'd then like to allow the user to skip that validation once he's been notified that "we like all comments to have a name." So, he submits the comment once, sees the notification, then can submit the form again unchanged if he really doesn't want to add a name, and the validates_presences_of :name is skipped. But, I'm not sure how to go about doing this. I thought about checking to see where the request is coming from, but after a create, errors are handed off to the "new" action, which is the same as actual "new" comments. I then thought about checking to see if flash[errors] were present, but that won't work because there are other validations a comment has to pass. Finally, I thought about trying a validates_presences_of :name, :unless = :notified but wasn't sure how to define notified. I honestly hate asking such an open ended question, but wasn't sure where to get started. So, is there a way to just check a certain validation once?

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  • Data validation best practices: how can I better construct user feedback?

    - by Cory Larson
    Data validation, whether it be domain object, form, or any other type of input validation, could theoretically be part of any development effort, no matter its size or complexity. I sometimes find myself writing informational or error messages that might seem harsh or demanding to unsuspecting users, and frankly I feel like there must be a better way to describe the validation problem to the user. I know that this topic is subjective and argumentative. I've migrated this question from StackOverflow where I originally asked it with little response. Basically, I'm looking for good resources on data validation and user feedback that results from it at a theoretical level. Topics and questions I'm interested in are: Content Should I be describing what the user did correctly or incorrectly, or simply what was expected? How much detail can the user read before they get annoyed? (e.g. Is "Username cannot exceed 20 characters." enough, or should it be described more fully, such as "The username cannot be empty, and must be at least 6 characters but cannot exceed 30 characters."?) Grammar How do I decide between phrases like "must not," "may not," or "cannot"? Delivery This can depend on the project, but how should the information be delivered to the user? Should it be obtrusive (e.g. JavaScript alerts) or friendly? Should they be displayed prominently? Immediately (i.e. without confirmation steps, etc.)? Logging Do you bother logging validation errors? Internationalization Some cultures prefer or better understand directness over subtlety and vice-versa (e.g. "Don't do that!" vs. "Please check what you've done."). How do I cater to the majority of users? I may edit this list as I think more about the topic, but I'm genuinely interested in proper user feedback techniques. I'm looking for things like research results, poll results, etc. I've developed and refined my own techniques over the years that users seem to be okay with, but I work in an environment where the users prefer to adapt to what you give them over speaking up about things they don't like. I'm interested in hearing your experiences in addition to any resources to which you may be able to point me.

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  • Data validation best practices: how can I better construct user feedback?

    - by Cory Larson
    Data validation, whether it be domain object, form, or any other type of input validation, could theoretically be part of any development effort, no matter its size or complexity. I sometimes find myself writing informational or error messages that might seem harsh or demanding to unsuspecting users, and frankly I feel like there must be a better way to describe the validation problem to the user. I know that this topic is subjective and argumentative. StackOverflow might not be the proper channel for diving into this subject, but like I've mentioned, we all run into this at some point or another. There are so many StackExchange sites now; if there is a better one, feel free to share! Basically, I'm looking for good resources on data validation and user feedback that results from it at a theoretical level. Topics and questions I'm interested in are: Content Should I be describing what the user did correctly or incorrectly, or simply what was expected? How much detail can the user read before they get annoyed? (e.g. Is "Username cannot exceed 20 characters." enough, or should it be described more fully, such as "The username cannot be empty, and must be at least 6 characters but cannot exceed 30 characters."?) Grammar How do I decide between phrases like "must not," "may not," or "cannot"? Delivery This can depend on the project, but how should the information be delivered to the user? Should it be obtrusive (e.g. JavaScript alerts) or friendly? Should they be displayed prominently? Immediately (i.e. without confirmation steps, etc.)? Logging Do you bother logging validation errors? Internationalization Some cultures prefer or better understand directness over subtlety and vice-versa (e.g. "Don't do that!" vs. "Please check what you've done."). How do I cater to the majority of users? I may edit this list as I think more about the topic, but I'm genuinely interest in proper user feedback techniques. I'm looking for things like research results, poll results, etc. I've developed and refined my own techniques over the years that users seem to be okay with, but I work in an environment where the users prefer to adapt to what you give them over speaking up about things they don't like. I'm interested in hearing your experiences in addition to any resources to which you may be able to point me.

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  • Domain Validation in a CQRS architecture

    - by Jupaol
    Basically I want to know if there is a better way to validate my domain entities. This is how I am planning to do it but I would like your opinion The first approach I considered was: class Customer : EntityBase<Customer> { public void ChangeEmail(string email) { if(string.IsNullOrWhitespace(email)) throw new DomainException(“...”); if(!email.IsEmail()) throw new DomainException(); if(email.Contains(“@mailinator.com”)) throw new DomainException(); } } I actually do not like this validation because even when I am encapsulating the validation logic in the correct entity, this is violating the Open/Close principle (Open for extension but Close for modification) and I have found that violating this principle, code maintenance becomes a real pain when the application grows up in complexity. Why? Because domain rules change more often than we would like to admit, and if the rules are hidden and embedded in an entity like this, they are hard to test, hard to read, hard to maintain but the real reason why I do not like this approach is: if the validation rules change, I have to come and edit my domain entity. This has been a really simple example but in RL the validation could be more complex So following the philosophy of Udi Dahan, making roles explicit, and the recommendation from Eric Evans in the blue book, the next try was to implement the specification pattern, something like this class EmailDomainIsAllowedSpecification : IDomainSpecification<Customer> { private INotAllowedEmailDomainsResolver invalidEmailDomainsResolver; public bool IsSatisfiedBy(Customer customer) { return !this.invalidEmailDomainsResolver.GetInvalidEmailDomains().Contains(customer.Email); } } But then I realize that in order to follow this approach I had to mutate my entities first in order to pass the value being valdiated, in this case the email, but mutating them would cause my domain events being fired which I wouldn’t like to happen until the new email is valid So after considering these approaches, I came out with this one, since I am going to implement a CQRS architecture: class EmailDomainIsAllowedValidator : IDomainInvariantValidator<Customer, ChangeEmailCommand> { public void IsValid(Customer entity, ChangeEmailCommand command) { if(!command.Email.HasValidDomain()) throw new DomainException(“...”); } } Well that’s the main idea, the entity is passed to the validator in case we need some value from the entity to perform the validation, the command contains the data coming from the user and since the validators are considered injectable objects they could have external dependencies injected if the validation requires it. Now the dilemma, I am happy with a design like this because my validation is encapsulated in individual objects which brings many advantages: easy unit test, easy to maintain, domain invariants are explicitly expressed using the Ubiquitous Language, easy to extend, validation logic is centralized and validators can be used together to enforce complex domain rules. And even when I know I am placing the validation of my entities outside of them (You could argue a code smell - Anemic Domain) but I think the trade-off is acceptable But there is one thing that I have not figured out how to implement it in a clean way. How should I use this components... Since they will be injected, they won’t fit naturally inside my domain entities, so basically I see two options: Pass the validators to each method of my entity Validate my objects externally (from the command handler) I am not happy with the option 1 so I would explain how I would do it with the option 2 class ChangeEmailCommandHandler : ICommandHandler<ChangeEmailCommand> { public void Execute(ChangeEmailCommand command) { private IEnumerable<IDomainInvariantValidator> validators; // here I would get the validators required for this command injected, and in here I would validate them, something like this using (var t = this.unitOfWork.BeginTransaction()) { var customer = this.unitOfWork.Get<Customer>(command.CustomerId); this.validators.ForEach(x =. x.IsValid(customer, command)); // here I know the command is valid // the call to ChangeEmail will fire domain events as needed customer.ChangeEmail(command.Email); t.Commit(); } } } Well this is it. Can you give me your thoughts about this or share your experiences with Domain entities validation EDIT I think it is not clear from my question, but the real problem is: Hiding the domain rules has serious implications in the future maintainability of the application, and also domain rules change often during the life-cycle of the app. Hence implementing them with this in mind would let us extend them easily. Now imagine in the future a rules engine is implemented, if the rules are encapsulated outside of the domain entities, this change would be easier to implement

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  • Application that will install application

    - by user23950
    I'm thinking of a software that comes with pc decrapifier. Which can do the exact opposite of what pc decrapifier can do. Install a number of applications in one click. Is there an application like that?Not a web app please, I already know of that but I forgot the name, so if you know that please comment.

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  • asp.net mvc client side validation; manually calling validation via javascript for ajax posts

    - by Jopache
    Under the built in client side validation (Microsoft mvc validation in mvc 2) using data annotations, when you try to submit a form and the fields are invalid, you will get the red validation summary next to the fields and the form will not post. However, I am using jquery form plugin to intercept the submit action on that form and doing the post via ajax. This is causing it to ignore validation; the red text shows up; but the form posts anyways. Is there an easy way to manually call the validation via javascript when I'm submitting the form? I am still kind of a javascript n00b. I tried googling it with no results and looking through the js source code makes my head hurt trying to figure it out. Or would you all recommend that I look in to some other validation framework? I liked the idea of jquery validate; but would like to define my validation requirements only in my viewmodel. Any experiences with xval or anything of the sort?

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  • Chossing an application server for an web application development

    - by harigm
    My manager has asked me to suggest an application server for the web application development work, What are the factors that needs to be considered before we select any application server for web application development in Java J2ee development? If I select one now and IN future, if I want to change to some other application server, Is if that minimum effort to change?

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