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  • Getting list of states/events from a model that AASM's

    - by Jason Nerer
    Hi, I successfully integrated the most recent AASM gem into an application, using it for the creation of a wizard. In my case I have a model order class Order < ActiveRecord::Base belongs_to :user has_one :billing_plan, :dependent => :destroy named_scope :with_user, ..... <snip> include AASM aasm_column :aasm_state aasm_initial_state :unauthenticated_user aasm_state :unauthenticated_user, :after_exit => [:set_state_completed] aasm_state : <snip> <and following the event definitions> end Now I would like to give an administrator the possibility to create his own graphs through the AASM states. Therefore I created two additional models called OrderFlow and Transition where there order_flow has many transitions and order belongs_to order_flow. No problem so far. Now I would like to give my admin the possibility to dynamically add existing transitions / events to an order_flow graph. The problem now is, that I do not find any possibility to get a list of all events / transitions out of my order model. aasm_states_for_select seems to be the correct candidate, but I cannot call it on my order model. Can anyone help? Thx in advance. J.

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  • Right way to return proxy model instance from a base model instance in Django ?

    - by sotangochips
    Say I have models: class Animal(models.Model): type = models.CharField(max_length=255) class Dog(Animal): def make_sound(self): print "Woof!" class Meta: proxy = True class Cat(Animal): def make_sound(self): print "Meow!" class Meta: proxy = True Let's say I want to do: animals = Animal.objects.all() for animal in animals: animal.make_sound() I want to get back a series of Woofs and Meows. Clearly, I could just define a make_sound in the original model that forks based on animal_type, but then every time I add a new animal type (imagine they're in different apps), I'd have to go in and edit that make_sound function. I'd rather just define proxy models and have them define the behavior themselves. From what I can tell, there's no way of returning mixed Cat or Dog instances, but I figured maybe I could define a "get_proxy_model" method on the main class that returns a cat or a dog model. Surely you could do this, and pass something like the primary key and then just do Cat.objects.get(pk = passed_in_primary_key). But that'd mean doing an extra query for data you already have which seems redundant. Is there any way to turn an animal into a cat or a dog instance in an efficient way? What's the right way to do what I want to achieve?

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  • Google App Engine django model form does not pick up BlobProperty

    - by Wes
    I have the following model: class Image(db.Model): auction = db.ReferenceProperty(Auction) image = db.BlobProperty() thumb = db.BlobProperty() caption = db.StringProperty() item_to_tag = db.StringProperty() And the following form: class ImageForm(djangoforms.ModelForm): class Meta: model = Image When I call ImageForm(), only the non-Blob fields are created, like this: <tr><th><label for="id_auction">Auction:</label></th><td><select name="auction" id="id_auction"> <option value="" selected="selected">---------</option> <option value="ahRoYXJ0bWFuYXVjdGlvbmVlcmluZ3INCxIHQXVjdGlvbhgKDA">2010-06-19 11:00:00</option> </select></td></tr> <tr><th><label for="id_caption">Caption:</label></th><td><input type="text" name="caption" id="id_caption" /></td></tr> <tr><th><label for="id_item_to_tag">Item to tag:</label></th><td><input type="text" name="item_to_tag" id="id_item_to_tag" /></td></tr> I want the Blob fields to be included in the form as well (as file inputs). What am I doing wrong?

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  • design an extendable database model

    - by wishi_
    Hi! Currently I'm doing a project whose specifications are unclear - well who doesn't. I wonder what's the best development strategy to design a DB, that's going to be extended sooner or later with additional tables and relations. I want to include "changeability". My main concern is that I want to apply design patterns (it's a university project) and I want to separate the constant factors from those, that change by choosing appropriate design patterns - in my case MVC and a set of sub-patterns at model level. When it comes to the DB however, I may have to resdesign my model in my MVC approach, because my domain model at a later stage my require a different set of classes representing the DB tables. I use Hibernate as an abstraction layer between DB and application. Would you start with a very minimal DB, just a few tables and relations? And what if I want an efficient DB, too? I wonder what strategies are applied in the real world. Stakeholder analysis for example isn't a sufficient planing solution when it comes to changing requirements. I think - at a DB level - my design pattern ends. So there's breach whose impact I'd like to minimize with a smart strategy.

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  • Model class for NSDictionary information with Lazy Loading

    - by samfu_1
    My application utilizes approx. 50+ .plists that are used as NSDictionaries. Several of my view controllers need access to the properties of the dictionaries, so instead of writing duplicate code to retrieve the .plist, convert the values to a dictionary, etc, each time I need the info, I thought a model class to hold the data and supply information would be appropriate. The application isn't very large, but it does handle a good deal of data. I'm not as skilled in writing model classes that conform to the MVC paradigm, and I'm looking for some strategies for this implementation that also supports lazy loading.. This model class should serve to supply data to any view controller that needs it and perform operations on the data (such as adding entries to dictionaries) when requested by the controller functions currently planned: returning the count on any dictionary adding one or more dictionaries together Currently, I have this method for supporting the count lookup for any dictionary. Would this be an example of lazy loading? -(NSInteger)countForDictionary: (NSString *)nameOfDictionary { NSBundle *bundle = [NSBundle mainBundle]; NSString *plistPath = [bundle pathForResource: nameOfDictionary ofType: @"plist"]; //load plist into dictionary NSMutableDictionary *dictionary = [[NSMutableDictionary alloc] initWithContentsOfFile: plistPath]; NSInteger count = [dictionary count] [dictionary release]; [return count] }

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  • CoreData is saving model without the save: method being called

    - by chris
    I have a list of items with a plus button in the navigation bar that opens up a modal window containing a table of the models attributes, that displays a form when the table items are clicked (pretty standard form style). For some reason if I click the plus button to open the form to create a new model, then immediately click the done button, the person model is saved. The action linked to the done button does nothing but call on a delegate method notifying the personListViewController to close the window. The apple docs do state that the model is not saved after calling the insertNewObjectForEntityName: ... Simply creating a managed object does not cause it to be saved to a persistent store. The managed object context acts as a scratchpad. I am at a lost to why this is happening, but every time I click the done button I have a new blank item in the original tableView. I am using SDK v3.1.3 // PersonListViewController - open modal window - (void)addPerson { // Load the new form PersonNewViewController *newController = [[PersonNewViewController alloc] init]; newController.modalFormDelegate = self; [self presentModalViewController:newController animated:YES]; [newController release]; } // PersonFormViewController - (void)viewDidLoad { [super viewDidLoad]; if ( person == nil ) { MyAppDelegate *appDelegate = [[UIApplication sharedApplication] delegate]; self.person = [NSEntityDescription insertNewObjectForEntityForName:@"Person" inManagedObjectContext:appDelegate.managedObjectContext]; } ... UIBarButtonItem *doneButton = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemDone target:self action:@selector(done)]; self.navigationItem.rightBarButtonItem = doneButton; [doneButton release]; } - (IBAction) done { [self.modalFormDelegate didCancel]; } // delegate method in the original listViewController - (void) didCancel { [self dismissModalViewControllerAnimated:YES]; }

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  • CakePHP: Need help using saveField to update a fields in a belongsTo model

    - by afrisch
    I am trying to update a password into two different models/tables in CakePHP. I can update it fine in the parent model, but not the second model. Models: Users (hasOne GameProfile) PK=id Gameprofiles (belongsTo User) FK=user_id Here is a stripped down version of my function in the Users_controller.php: function updatepass() { if (!empty($this->data)) { $this->User->id = $this->Auth->user('id'); $this->User->saveField('sha1password', $this->Auth->password($this->data['User']['newpass'])); $this->User->Gameprofile->saveField('plainpassword', $this->data['User']['newpass']); } } When I execute the function, the users table is updated fine. But the gameprofile table is not updated, rather Cake does an insert. SQL Query Log: 1195 Query UPDATE `users` SET `sha1password` = 'e9443e9f5e1a07832aad1b2f84de1a666daf89b5' WHERE `users`.`id` = 30 1195 Query INSERT INTO `gameprofiles` (`plainpassword`) VALUES ('abc') Is there a way to get CakePHP to do an update using saveField on a model with a belongsTo attribute? I've tried various ways to refer to user_id before executing the second saveField, but just can't seem to find the winning combination. Any help is greatly appreciated!

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  • [Ruby on Rails] complex model relationship

    - by siulamvictor
    I am not sure am I doing these correct. I have 3 models, Account, User, and Event. Account contains a group of Users. Each User have its own username and password for login, but they can access the same Account data under the same Account. Events is create by a User, which other Users in the same Account can also read or edit it. I created the following migrations and models. User migration class CreateUsers < ActiveRecord::Migration def self.up create_table :users do |t| t.integer :account_id t.string :username t.string :password t.timestamps end end def self.down drop_table :users end end Account migration class CreateAccounts < ActiveRecord::Migration def self.up create_table :accounts do |t| t.string :name t.timestamps end end def self.down drop_table :accounts end end Event migration class CreateEvents < ActiveRecord::Migration def self.up create_table :events do |t| t.integer :account_id t.integer :user_id t.string :name t.string :location t.timestamps end end def self.down drop_table :events end end Account model class Account < ActiveRecord::Base has_many :users has_many :events end User model class User < ActiveRecord::Base belongs_to :account end Event model class Event < ActiveRecord::Base belongs_to :account belongs_to :user end so.... Is this setting correct? Every time when a user create a new account, the system will as for the user information, i.e. username and password. How can I add them into correct tables? How can I add a new event? I am sorry for such a long question. I am not very understand the rails way in handling such data structure. Thank you guys for answering me. :)

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  • Reordering fields in Django model

    - by Alex Lebedev
    I want to add few fields to every model in my django application. This time it's created_at, updated_at and notes. Duplicating code for every of 20+ models seems dumb. So, I decided to use abstract base class which would add these fields. The problem is that fields inherited from abstract base class come first in the field list in admin. Declaring field order for every ModelAdmin class is not an option, it's even more duplicate code than with manual field declaration. In my final solution, I modified model constructor to reorder fields in _meta before creating new instance: class MyModel(models.Model): # Service fields notes = my_fields.NotesField() created_at = models.DateTimeField(auto_now_add=True) updated_at = models.DateTimeField(auto_now=True) class Meta: abstract = True last_fields = ("notes", "created_at", "updated_at") def __init__(self, *args, **kwargs): new_order = [f.name for f in self._meta.fields] for field in self.last_fields: new_order.remove(field) new_order.append(field) self._meta._field_name_cache.sort(key=lambda x: new_order.index(x.name)) super(TwangooModel, self).__init__(*args, **kwargs) class ModelA(MyModel): field1 = models.CharField() field2 = models.CharField() #etc ... It works as intended, but I'm wondering, is there a better way to acheive my goal?

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  • Asp.net MVC - Model binding image button

    - by big dave
    I've got a very complex form and i'm using the MVC model binding to capture all the information I've got it set up to capture all the different submissions that can happen as there are about 10 different submit buttons on the form, and there are also 2 image buttons I tried to get a bit clever (or so i thought) with capturing the image button submissions, and have created a child class so that i can capture the x value that's returned public class ImageButtonViewData { public int x { get; set; } public string Value { get; set; } } The parent class looks something like this public class ViewDataObject { public ImageButtonViewData ImageButton { get; set; } public ViewDataObject(){ this.ImageButton = new ImageButton(); } } The html for the image button then looks like <input type="image" id="ViewDataObject_ImageButton" name="ViewDataObject.ImageButton" /> This works fine in all browsers except for Chrome. When i debug it in chrome, the Request.Form object contains the values that i would expect, but after the model binding has occurred, the ImageButton property on the ViewDataObject has been set to null The only difference that i can see between the submission values is that Chrome passes the x as lower case (ViewDataObject.ImageButton.x) and IE passes it as upper case (ViewDataObject.ImageButton.X) but i didn't think that model binding took any notice of casing on property names Does anyone have any ideas ?

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  • WPF binding comboboxes to parent- child model

    - by PaulB
    I've got a model with a few tiers in it - something along the lines of ... Company Employees Phone numbers So I've got a ListBox showing all the companys in the model. Each ListBoxItem then contains two comboboxes ... one for employees, one for phone numbers. I can successfully get the employee combo to bind correctly and show the right people, but I'd like the phone combo to show the numbers for the selected employee. I'm just setting the DataContext of the ListBox to the model above and using the following data template for each item <DataTemplate x:Key="CompanyBody"> <StackPanel Orientation="Horizontal"> <Label Content="{Binding Path=CompanyName}"></Label> <ComboBox Name="EmployeesCombo" ItemsSource="{Binding Path=Company.Employees}"></ComboBox> <!-- What goes here --> <ComboBox DataContext="???" ItemsSource="??" ></ComboBox> </StackPanel> </DataTemplate> I've tried (naively) <ComboBox ItemsSource="{Binding Path=Company.Employees.PhoneNumbers}" ></ComboBox> and <ComboBox DataContext="EmployeesCombo.SelectedValue" ItemsSource="{Binding Path=PhoneNumbers}" ></ComboBox> and all other manner of combinations ...

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  • UpdateModelFromDatabaseException when trying to add a table to Entity Framework model

    - by Agent_9191
    I'm running into a weird issue with Entity Framework in .NET 3.5 SP1 within Visual Studio 2008. I created a database with a few tables in SQL Server and then created the associated .edmx Entity Framework model and had no issues. I then created a new table in the database that has a foreign key to an existing table and needed to be added to the .edmx. So I opened the .edmx in Visual Studio and in the models right-clicked and chose "Update Model From Database...". I saw the new table in the "add" tab, so I checked it and clicked finish. However I get an error message with the following text: --------------------------- Microsoft Visual Studio --------------------------- An exception of type 'Microsoft.Data.Entity.Design.Model.Commands.UpdateModelFromDatabaseException' occurred while attempting to update from the database. The exception message is: 'Cannot update from the database. Cannot resolve the Name Target for ScalarProperty 'ID <==> CustomerID'.'. --------------------------- OK --------------------------- For reference, here's the tables seem to be the most pertinent to the error. CustomerPreferences already exists in the .edmx. Diets is the table that was added afterwards and trying to add to the .edmx. CREATE TABLE [dbo].[CustomerPreferences]( [ID] [uniqueidentifier] NOT NULL, [LastUpdatedTime] [datetime] NOT NULL, [LastUpdatedBy] [uniqueidentifier] NOT NULL, PRIMARY KEY CLUSTERED ( [ID] ASC )WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY] ) ON [PRIMARY] CREATE TABLE [dbo].[Diets]( [ID] [uniqueidentifier] NOT NULL, [CustomerID] [uniqueidentifier] NOT NULL, [Description] [nvarchar](50) NOT NULL, [LastUpdatedTime] [datetime] NOT NULL, [LastUpdatedBy] [uniqueidentifier] NOT NULL, PRIMARY KEY CLUSTERED ( [ID] ASC )WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY] ) ON [PRIMARY] GO ALTER TABLE [dbo].[Diets] WITH CHECK ADD CONSTRAINT [FK_Diets_CustomerPreferences] FOREIGN KEY([CustomerID]) REFERENCES [dbo].[CustomerPreferences] ([ID]) GO ALTER TABLE [dbo].[Diets] CHECK CONSTRAINT [FK_Diets_CustomerPreferences] GO This seems like a fairly common use case, so I'm not sure where I'm going wrong.

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  • Creation of model in core data on the fly

    - by user1740045
    How can we create a model in core data on the fly? I.e getting the schema of database from somewhere and then creating a Core Data Object graph? *QuesTion:* Yes thats fine, agreed with all the advantages. But, can anybody can tell practically, what is the benefit of integrating Core Data into project instead of using SQL directly. 1.No need to write SQL boiler plate code [but need to learn Core Data Model (steep curve)] 2.WE can undo and redo changes [but practically who needs it] 3.we can migrate to another schema [that can be done by SQLite as well jus need to add another field into table] 4.For say aggregation on some field in table,in Core Data we need to loop through Core Data Objects whereas in SQLite we need to first write SQLite Boiler Plate Code and then the basic aggregation SQL query,which is easy to write,only length of code will increase...But in case of Core Data (need to learn a lot). So apart from reducing the length of Code,does it actually adds value to project? or in terms of Memory Efficiency,Performance,etc.. PS: If anybody has actualy worked on Core Data(Model Creation On the Fly) , if possible share and gve pointers..thanks!

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  • How to integrate KVC in MVC?

    - by Paperflyer
    So I have an MVC-application in Cocoa. There are some custom views, a controller and a model. Of course, the views need to know some stuff, so they get their data from the controller. However, they do not use accessors in the controller, they use KVC with a keypath that calls right through to the model: // In view.m time = [timeSource valueForKeyPath:@"theModel.currentTime"]; // timeSource is a pseudo-delegate of the view that holds the controller This simplifies things a great deal and technically, the views still don't know the model in person (that is, in pointer). But of course, they access it directly. Is that a usual (or at least sensible) usage of KVC and MVC? Or how would you implement this kind of communication?

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  • django 1.1 beta issue

    - by ha22109
    Hello all, I m using django 1.1 beta.I m facing porblem in case of list_editable.First it was throughing exception saying need ordering in case of list_editable" then i added ordering in model but know it is giving me error.The code is working fine with django1.1 final. here is my code model.py class User(models.Model): advertiser = models.ForeignKey(WapUser,primary_key=True) status = models.CharField(max_length=20,choices=ADVERTISER_INVITE_STATUS,default='invited') tos_version = models.CharField(max_length=5) contact_email = models.EmailField(max_length=80) contact_phone = models.CharField(max_length=15) contact_mobile = models.CharField(max_length=15) contact_person = models.CharField(max_length=80) feedback=models.BooleanField(choices=boolean_choices,default=0) def __unicode__(self): return self.user.login class Meta: db_table = u'roi_advertiser_info' managed=False ordering=['feedback',] admin.py class UserAdmin(ReadOnlyAdminFields, admin.ModelAdmin): list_per_page = 15 fields = ['advertiser','contact_email','contact_phone','contact_mobile','contact_person'] list_display = ['advertiser','contact_email','contact_phone','contact_mobile','contact_person','status','feedback'] list_editable=['feedback'] readonly = ('advertiser',) search_fields = ['advertiser__login_id'] radio_fields={'approve_auto': admin.HORIZONTAL} list_filter=['status','feedback'] admin.site.register(User,UserADmin)

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  • Subsonic custom mapping of objects to tables

    - by codekaizen
    Geeting, I'm using Compact Framework 3.5 and have tenatively settled on a custom build of Subsonic 3.0 to do data access. The trouble is that I am used to developing model-first but am also interested in keeping control of my DB schema. Therefore, neither ActiveRecord or Repository appears to meet my needs, and I want to use my existing POCO model and map it to my existing tables. I'm used to doing this via NHibernate and Entity Framework. After some investigation, it appears that I might be able to author a custom QueryMapping to give me the custom mapping I want. Before I start down this path, however, I'd like to see some kind of example of this being done. I can't seem to find any on the web, and wonder if anyone could give input on experience with Subsonic, model-first and a custom Table-per-Type and Table-per-Hierarchy mapping.

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  • list editabale error

    - by ha22109
    Hello all, I m using django 1.1 beta.I m facing porblem in case of list_editable.First it was throughing exception saying need ordering in case of list_editable" then i added ordering in model but know it is giving me error.The code is working fine with django1.1 final. here is my code model.py class User(models.Model): advertiser = models.ForeignKey(WapUser,primary_key=True) status = models.CharField(max_length=20,choices=ADVERTISER_INVITE_STATUS,default='invited') tos_version = models.CharField(max_length=5) contact_email = models.EmailField(max_length=80) contact_phone = models.CharField(max_length=15) contact_mobile = models.CharField(max_length=15) contact_person = models.CharField(max_length=80) feedback=models.BooleanField(choices=boolean_choices,default=0) def __unicode__(self): return self.user.login class Meta: db_table = u'roi_advertiser_info' managed=False ordering=['feedback',] admin.py class UserAdmin(ReadOnlyAdminFields, admin.ModelAdmin): list_per_page = 15 fields = ['advertiser','contact_email','contact_phone','contact_mobile','contact_person'] list_display = ['advertiser','contact_email','contact_phone','contact_mobile','contact_person','status','feedback'] list_editable=['feedback'] readonly = ('advertiser',) search_fields = ['advertiser__login_id'] radio_fields={'approve_auto': admin.HORIZONTAL} list_filter=['status','feedback'] admin.site.register(User,UserADmin)

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  • MVC DateTime binding with incorrect date format

    - by Sam Wessel
    Asp.net-MVC now allows for implicit binding of DateTime objects. I have an action along the lines of public ActionResult DoSomething(DateTime startDate) { ... } This successfully converts a string from an ajax call into a DateTime. However, we use the date format dd/MM/yyyy; MVC is converting to MM/dd/yyyy. For example, submitting a call to the action with a string '09/02/2009' results in a DateTime of '02/09/2009 00:00:00', or September 2nd in our local settings. I don't want to roll my own model binder for the sake of a date format. But it seems needless to have to change the action to accept a string and then use DateTime.Parse if MVC is capable of doing this for me. Is there any way to alter the date format used in the default model binder for DateTime? Shouldn't the default model binder use your localisation settings anyway?

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  • User settings mechanism for Yii

    - by Peterim
    Hi guys! I need some help with user settings mechanism for my Yii-based application. I've created the following db structure to store user settings: table user with the following fields id | username | email | etc. table settingslist (to store a list of all possible settings with descriptions) with the following fields id | code | name | description table settings (to store all user settings) with the following fields id | userid | settingslistcode | value Now I'm stuck with the form which allows user to change his settings. I had to deal before with the regular models (i.e. for posts, comments, etc.) where every new model had only one row in the database (Post model - id | title | body |) with the certain amount of attributes (fields of the table). But now I need to store user settings in 10-15 rows and I don't know how to apply Yii model mechanism to work with this, so I can retrieve those settings in a single form (so user could change his preferences). Any suggestions are greatly appreciated. Thank you!

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  • Rendering HTML in rails without actually displaying it

    - by Kevin Whitaker
    Hello all, My current project requires me to assemble a .zip file containing HTML and text-only templates for a user to download, for importing into an email marketing program. I've inherited this project, and currently the code uses a "fake" model (that is a model that does not directly correlate to a database table), in which it stores the entire template in a string, using dynamic variables to populate certain areas. The "fake" model then has a method for creating a zip file. It seems to me that there has to be a better way to do this. I was wondering if there was a way to move the template into a .erb/haml file, and then write a method that would populate the file in preparation for being zipped up? Basically, is there a way to render an HTML and text file, without actually having to display them? Thanks for any help.

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  • MVVM in Task-It

    As I'm gearing up to write a post about dynamic XAP loading with MEF, I'd like to first talk a bit about MVVM, the Model-View-ViewModel pattern, as I will be leveraging this pattern in my future posts. Download Source Code Why MVVM? Your first question may be, "why do I need this pattern? I've been using a code-behind approach for years and it works fine." Well, you really don't have to make the switch to MVVM, but let me first explain some of the benefits I see for doing so. MVVM Benefits Testability - This is the one you'll probably hear the most about when it comes to MVVM. Moving most of the code from your code-behind to a separate view model class means you can now write unit tests against the view model without any knowledge of a view (UserControl). Multiple UIs - Let's just say that you've created a killer app, it's running in the browser, and maybe you've even made it run out-of-browser. Now what if your boss comes to you and says, "I heard about this new Windows Phone 7 device that is coming out later this year. Can you start porting the app to that device?". Well, now you have to create a new UI (UserControls, etc.) because you have a lot less screen real estate to work with. So what do you do, copy all of your existing UserControls, paste them, rename them, and then start changing the code? Hmm, that doesn't sound so good. But wait, if most of the code that makes your browser-based app tick lives in view model classes, now you can create new view (UserControls) for Windows Phone 7 that reference the same view model classes as your browser-based app. Page state - In Silverlight you're at some point going to be faced with the same issue you dealt with for years in ASP.NET, maintaining page state. Let's say a user hits your Products page, does some stuff (filters record, etc.), then leaves the page and comes back later. It would be best if the Products page was in the same state as when they left it right? Well, if you've thrown away your view (UserControl or Page) and moved off to another part of the UI, when you come back to Products you're probably going to re-instantiate your view...which will put it right back in the state it was when it started. Hmm, not good. Well, with a little help from MEF you can store the state in your view model class, MEF will keep that view model instance hanging around in memory, and then you simply rebind your view to the view model class. I made that sound easy, but it's actually a bit of work to properly store and restore the state. At least it can be done though, which will make your users a lot happier! I'll talk more about this in an upcoming blog post. No event handlers? Another nice thing about MVVM is that you can bind your UserControls to the view model, which may eliminate the need for event handlers in your code-behind. So instead of having a Click handler on a Button (or RadMenuItem), for example, you can now bind your control's Command property to a DelegateCommand in your view model (I'll talk more about Commands in an upcoming post). Instead of having a SelectionChanged event handler on your RadGridView you can now bind its SelectedItem property to a property in your view model, and each time the user clicks a row, the view model property's setter will be called. Now through the magic of binding we can eliminate the need for traditional code-behind based event handlers on our user interface controls, and the best thing is that the view model knows about everything that's going on...which means we can test things without a user interface. The brains of the operation So what we're seeing here is that the view is now just a dumb layer that binds to the view model, and that the view model is in control of just about everything, like what happens when a RadGridView row is selected, or when a RadComboBoxItem is selected, or when a RadMenuItem is clicked. It is also responsible for loading data when the page is hit, as well as kicking off data inserts, updates and deletions. Once again, all of this stuff can be tested without the need for a user interface. If the test works, then it'll work regardless of whether the user is hitting the browser-based version of your app, or the Windows Phone 7 version. Nice! The database Before running the code for this app you will need to create the database. First, create a database called MVVMProject in SQL Server, then run MVVMProject.sql in the MVVMProject/Database directory of your downloaded .zip file. This should give you a Task table with 3 records in it. When you fire up the solution you will also need to update the connection string in web.config to point to your database instead of IBM12\SQLSERVER2008. The code One note about this code is that it runs against the latest Silverlight 4 RC and WCF RIA Services code. Please see my first blog post about updating to the RC bits. Beta to RC - Part 1 At the top of this post is a link to a sample project that demonstrates a sample application with a Tasks page that uses the MVVM pattern. This is a simplified version of how I have implemented the Tasks page in the Task-It application. Youll notice that Tasks.xaml has very little code to it. Just a TextBlock that displays the page title and a ContentControl. <StackPanel>     <TextBlock Text="Tasks" Style="{StaticResource PageTitleStyle}"/>     <Rectangle Style="{StaticResource StandardSpacerStyle}"/>     <ContentControl x:Name="ContentControl1"/> </StackPanel> In List.xaml we have a RadGridView. Notice that the ItemsSource is bound to a property in the view model class call Tasks, SelectedItem is bound to a property in the view model called SelectedItem, and IsBusy is bound to a property in the view model called IsLoading. <Grid>     <telerikGridView:RadGridView ItemsSource="{Binding Tasks}" SelectedItem="{Binding SelectedItem, Mode=TwoWay}"                                  IsBusy="{Binding IsLoading}" AutoGenerateColumns="False" IsReadOnly="True" RowIndicatorVisibility="Collapsed"                IsFilteringAllowed="False" ShowGroupPanel="False">         <telerikGridView:RadGridView.Columns>             <telerikGridView:GridViewDataColumn Header="Name" DataMemberBinding="{Binding Name}" Width="3*"/>             <telerikGridView:GridViewDataColumn Header="Due" DataMemberBinding="{Binding DueDate}" DataFormatString="{}{0:d}" Width="*"/>         </telerikGridView:RadGridView.Columns>     </telerikGridView:RadGridView> </Grid> In Details.xaml we have a Save button that is bound to a property called SaveCommand in our view model. We also have a simple form (Im using a couple of controls here from Silverlight.FX for the form layout, FormPanel and Label simply because they make for a clean XAML layout). Notice that the FormPanel is also bound to the SelectedItem in the view model (the same one that the RadGridView is). The two form controls, the TextBox and RadDatePicker) are bound to the SelectedItem's Name and DueDate properties. These are properties of the Task object that WCF RIA Services creates. <StackPanel>     <Button Content="Save" Command="{Binding SaveCommand}" HorizontalAlignment="Left"/>     <Rectangle Style="{StaticResource StandardSpacerStyle}"/>     <fxui:FormPanel DataContext="{Binding SelectedItem}" Style="{StaticResource FormContainerStyle}">         <fxui:Label Text="Name:"/>         <TextBox Text="{Binding Name, Mode=TwoWay}"/>         <fxui:Label Text="Due:"/>         <telerikInput:RadDatePicker SelectedDate="{Binding DueDate, Mode=TwoWay}"/>     </fxui:FormPanel> </StackPanel> In the code-behind of the Tasks control, Tasks.xaml.cs, I created an instance of the view model class (TasksViewModel) in the constructor and set it as the DataContext for the control. The Tasks page will load one of two child UserControls depending on whether you are viewing the list of tasks (List.xaml) or the form for editing a task (Details.xaml). // Set the DataContext to an instance of the view model class var viewModel = new TasksViewModel(); DataContext = viewModel;   // Child user controls (inherit DataContext from this user control) List = new List(); // RadGridView Details = new Details(); // Form When the page first loads, the List is loaded into the ContentControl. // Show the RadGridView first ContentControl1.Content = List; In the code-behind we also listen for a couple of the view models events. The ItemSelected event will be fired when the user clicks on a record in the RadGridView in the List control. The SaveCompleted event will be fired when the user clicks Save in the Details control (the form). Here the view model is in control, and is letting the view know when something needs to change. // Listeners for the view model's events viewModel.ItemSelected += OnItemSelected; viewModel.SaveCompleted += OnSaveCompleted; The event handlers toggle the view between the RadGridView (List) and the form (Details). void OnItemSelected(object sender, RoutedEventArgs e) {     // Show the form     ContentControl1.Content = Details; }   void OnSaveCompleted(object sender, RoutedEventArgs e) {     // Show the RadGridView     ContentControl1.Content = List; } In TasksViewModel, we instantiate a DataContext object and a SaveCommand in the constructor. DataContext is a WCF RIA Services object that well use to retrieve the list of Tasks and to save any changes to a task. Ill talk more about this and Commands in future post, but for now think of the SaveCommand as an event handler that is called when the Save button in the form is clicked. DataContext = new DataContext(); SaveCommand = new DelegateCommand(OnSave); When the TasksViewModel constructor is called we also make a call to LoadTasks. This sets IsLoading to true (which causes the RadGridViews busy indicator to appear) and retrieves the records via WCF RIA Services.         public LoadOperation<Task> LoadTasks()         {             // Show the loading message             IsLoading = true;             // Get the data via WCF RIA Services. When the call has returned, called OnTasksLoaded.             return DataContext.Load(DataContext.GetTasksQuery(), OnTasksLoaded, false);         } When the data is returned, OnTasksLoaded is called. This sets IsLoading to false (which hides the RadGridViews busy indicator), and fires property changed notifications to the UI to let it know that the IsLoading and Tasks properties have changed. This property changed notification basically tells the UI to rebind. void OnTasksLoaded(LoadOperation<Task> lo) {     // Hide the loading message     IsLoading = false;       // Notify the UI that Tasks and IsLoading properties have changed     this.OnPropertyChanged(p => p.Tasks);     this.OnPropertyChanged(p => p.IsLoading); } Next lets look at the view models SelectedItem property. This is the one thats bound to both the RadGridView and the form. When the user clicks a record in the RadGridView its setter gets called (set a breakpoint and see what I mean). The other code in the setter lets the UI know that the SelectedItem has changed (so the form displays the correct data), and fires the event that notifies the UI that a selection has occurred (which tells the UI to switch from List to Details). public Task SelectedItem {     get { return _selectedItem; }     set     {         _selectedItem = value;           // Let the UI know that the SelectedItem has changed (forces it to re-bind)         this.OnPropertyChanged(p => p.SelectedItem);         // Notify the UI, so it can switch to the Details (form) page         NotifyItemSelected();     } } One last thing, saving the data. When the Save button in the form is clicked it fires the SaveCommand, which calls the OnSave method in the view model (once again, set a breakpoint to see it in action). public void OnSave() {     // Save the changes via WCF RIA Services. When the save is complete, call OnSaveCompleted.     DataContext.SubmitChanges(OnSaveCompleted, null); } In OnSave, we tell WCF RIA Services to submit any changes, which there will be if you changed either the Name or the Due Date in the form. When the save is completed, it calls OnSaveCompleted. This method fires a notification back to the UI that the save is completed, which causes the RadGridView (List) to show again. public virtual void OnSaveCompleted(SubmitOperation so) {     // Clear the item that is selected in the grid (in case we want to select it again)     SelectedItem = null;     // Notify the UI, so it can switch back to the List (RadGridView) page     NotifySaveCompleted(); } Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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  • Model M Keyboard inputs incorrect characters after logging in to Fedora

    - by mickburkejnr
    I recently bought a 24 year old IBM Model M keyboard. From what I gather, it'd been left on a shelf for the last 5 years, so you can imagine the amount of dust dirt and crap that was on it. Before cleaning it, I plugged it in to my laptop (running Fedora 17) using a PS/2 to USB adapter. What I found was, while it still works, the keys I press don't correspond to what is displayed on the screen. So for example, when I type S on the keyboard, I get ß display on the screen instead. At the time, I put this down to the adapter not working properly. Since then, I stripped the keys off the keyboard and cleaned the whole thing. It looks like it's just come out of a box! I then plugged it in to my computer (also running Fedora 17) via a standard PS/2 plug. The computer loaded up to the login screen, and I typed in my password. Pressed enter, and I logged straight in to my machine. At this point, I opened up a text editor and started typing some stuff. To my horror, the keystrokes I was entering weren't coming up as intended. What came up instead were characters that would map to the pressed key but only under a different keyboard language setting. I opened up a program to see what keyboard language had been selected, and the correct one for the keyboard was selected (which is UK in my case). I opened up a window that would show what characters mapped to what keys, and I pressed every single key on the keyboard, and every corresponding block representing each key lit up. I went back to the text editor to try again, but I was still getting these random characters. Whats more is that the backspace key would not work, although in the other utility it would flash when pressed. What I know is that at the login screen the keyboard must have entered the correct characters, otherwise I wouldn't have been able to log in. Further more, keys that don't respond while using a text editor as sending signals to the computer, as illustrated in that keyboard utility. The question is why random characters are displayed when they really shouldn't be? Would this be a hardware fault or a software issue?

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  • WPF DataContext does not refresh the DataGrid using MVVM model

    - by vikram bhatia
    Project Overview I have a view which binds to a viewmodel containing 2 ObserverableCollection. The viewmodel constructor populates the first ObserverableCollection and the view datacontext is collected to bind to it through a public property called Sites. Later the 2ed ObserverableCollection is populated in the LoadOrders method and the public property LoadFraudResults is updated for binding it with datacontext. I am using WCF to pull the data from the database and its getting pulled very nicely. VIEWMODEL SOURCE class ManageFraudOrderViewModel:ViewModelBase { #region Fields private readonly ICollectionView collectionViewSites; private readonly ICollectionView collectionView; private ObservableCollection<GeneralAdminService.Website> _sites; private ObservableCollection<FraudService.OrderQueue> _LoadFraudResults; #endregion #region Properties public ObservableCollection<GeneralAdminService.Website> Sites { get { return this._sites; } } public ObservableCollection<FraudService.OrderQueue> LoadFraudResults { get { return this._LoadFraudResults;} } #endregion public ManageFraudOrderViewModel() { //Get values from wfc service model GeneralAdminService.GeneralAdminServiceClient generalAdminServiceClient = new GeneralAdminServiceClient(); GeneralAdminService.Website[] websites = generalAdminServiceClient.GetWebsites(); //Get values from wfc service model if (websites.Length > 0) { _sites = new ObservableCollection<Wqn.Administration.UI.GeneralAdminService.Website>(); foreach (GeneralAdminService.Website website in websites) { _sites.Add((Wqn.Administration.UI.GeneralAdminService.Website)website); } this.collectionViewSites= CollectionViewSource.GetDefaultView(this._sites); } generalAdminServiceClient.Close(); } public void LoadOrders(Wqn.Administration.UI.FraudService.Website website) { //Get values from wfc service model FraudServiceClient fraudServiceClient = new FraudServiceClient(); FraudService.OrderQueue[] OrderQueue = fraudServiceClient.GetFraudOrders(website); //Get values from wfc service model if (OrderQueue.Length > 0) { _LoadFraudResults = new ObservableCollection<Wqn.Administration.UI.FraudService.OrderQueue>(); foreach (FraudService.OrderQueue orderQueue in OrderQueue) { _LoadFraudResults.Add(orderQueue); } } this.collectionViewSites= CollectionViewSource.GetDefaultView(this._LoadFraudResults); fraudServiceClient.Close(); } } VIEW SOURCE public partial class OrderQueueControl : UserControl { private ManageFraudOrderViewModel manageFraudOrderViewModel ; private OrderQueue orderQueue; private ButtonAction ButtonAction; private DispatcherTimer dispatcherTimer; public OrderQueueControl() { LoadOrderQueueForm(); } #region LoadOrderQueueForm private void LoadOrderQueueForm() { //for binding the first observablecollection manageFraudOrderViewModel = new ManageFraudOrderViewModel(); this.DataContext = manageFraudOrderViewModel; } #endregion private void cmbWebsite_SelectionChanged(object sender, SelectionChangedEventArgs e) { BindItemsSource(); } #region BindItemsSource private void BindItemsSource() { using (OverrideCursor cursor = new OverrideCursor(Cursors.Wait)) { if (!string.IsNullOrEmpty(Convert.ToString(cmbWebsite.SelectedItem))) { Wqn.Administration.UI.FraudService.Website website = (Wqn.Administration.UI.FraudService.Website)Enum.Parse(typeof(Wqn.Administration.UI.FraudService.Website),cmbWebsite.SelectedItem.ToString()); //for binding the second observablecollection******* manageFraudOrderViewModel.LoadOrders(website); this.DataContext = manageFraudOrderViewModel; //for binding the second observablecollection******* } } } #endregion } XAML ComboBox x:Name="cmbWebsite" ItemsSource="{Binding Sites}" Margin="5" Width="100" Height="25" SelectionChanged="cmbWebsite_SelectionChanged" DataGrid ItemsSource ={Binding Path = LoadFraudResults} PROBLEM AREA: When I call the LoadOrderQueueForm to bind the first observablecollection and later BindItemsSource to bind 2ed observable collection, everything works fine and no problem for the first time binding. But, when I call BindItemsSource again to repopulate the obseravablecollection based on changed selected combo value via cmbWebsite_SelectionChanged, the observalblecollection gets populated with new value and LoadFraudResults property in viewmodule is populated with new values; but when i call the datacontext to rebind the datagrid,the datagrid does not reflect the changed values. In other words the datagrid doesnot get changed when the datacontext is called the 2ed time in BindItemsSource method of the view. manageFraudOrderViewModel.LoadOrders(website); this.DataContext = manageFraudOrderViewModel; manageFraudOrderViewModel values are correct but the datagrid is not relected with changed values. Please help as I am stuck with this thing for past 2 days and the deadline is approaching near. Thanks in advance

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  • XForms and multiple inputs for same model tag

    - by iHeartGreek
    Hi! I apologize ahead of time if I am not asking this properly.. it is hard to put into words what I am asking.. I have XForms model such as: <file> <criteria> <criterion></criterion> </criteria> </file> I want to have multiple input text boxes that create a new criterion tag. user interface such as: <xf:input ref="/file/criteria/criterion" model="select_data"> <xf:label>Select</xf:label> </xf:input> <xf:input ref="/file/criteria/criterion" model="select_data"> <xf:label>Select</xf:label> </xf:input> <xf:input ref="/file/criteria/criterion" model="select_data"> <xf:label>Select</xf:label> </xf:input> And I would like the XML output to look like this (once user has entered in info): <file> <criteria> <criterion>AAA</criterion> <criterion>BBB</criterion> <criterion>CCC</criterion> </criteria> </file> The way I have it doesn't work, as it sees the 3 input fields to be referring all to the same criterion tag. How do I differentiate? Thanks! I hope that made some sense! BEGIN FIRST EDIT Thanks for the responses for the basic text box! However, I now need to do this with a listbox. But for the life of me, I can't figure out how. I read somewhere to use with the xforms:select and deselect events.. but I didn't know where to place them, and the places I tried gave me very weird behaviour. I am currently implementing the following: <xf:select ref="instance('criteria_data')/criteria/criterion" selection="" appearance="compact" > <xf:label>Choose criteria</xf:label> <xf:itemset nodeset="instance('criteria_choices')/choice"> <xf:label ref="@label"></xf:label> <xf:value ref="."></xf:value> </xf:itemset> </xf:select> However when multiple choices are submitted, all selection values are inserted into the same node, separated by spaces. For example: If AAA and BBB and FFF were selected from listbox, it would result in the following XML: <criterion>AAA BBB FFF</criterion> How do I change my code to have each selection be in a separate node? i.e. I want it to look like this: <criterion>AAA</criterion> <criterion>BBB</criterion> <criterion>FFF</criterion> Thanks! END FIRST EDIT BEGIN SECOND EDIT: For the listboxes (ie xf:select appearance="compact") I ended up allowing the spaces to occur in the same node and then just transformed that xml using xsl to generate a properly formatted new xml doc (with separate individual nodes). Unfortunately, I did not find a less cumbersome solution by inserting them originally into separate nodes. The selected answer works very well for text boxes however, hence why I selected it as the answer. END SECOND EDIT

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  • Why is String Templating Better Than String Concatenation from an Engineering Perspective?

    - by stephen
    I once read (I think it was in "Programming Pearls") that one should use templates instead of building the string through the use of concatenation. For example, consider the template below (using C# razor library) <in a properties file> Browser Capabilities Type = @Model.Type Name = @Model.Browser Version = @Model.Version Supports Frames = @Model.Frames Supports Tables = @Model.Tables Supports Cookies = @Model.Cookies Supports VBScript = @Model.VBScript Supports Java Applets = @Model.JavaApplets Supports ActiveX Controls = @Model.ActiveXControls and later, in a separate code file private void Button1_Click(object sender, System.EventArgs e) { BrowserInfoTemplate = Properties.Resources.browserInfoTemplate; // see above string browserInfo = RazorEngine.Razor.Parse(BrowserInfoTemplate, browser); ... } From a software engineering perspective, how is this better than an equivalent string concatentation, like below: private void Button1_Click(object sender, System.EventArgs e) { System.Web.HttpBrowserCapabilities browser = Request.Browser; string s = "Browser Capabilities\n" + "Type = " + browser.Type + "\n" + "Name = " + browser.Browser + "\n" + "Version = " + browser.Version + "\n" + "Supports Frames = " + browser.Frames + "\n" + "Supports Tables = " + browser.Tables + "\n" + "Supports Cookies = " + browser.Cookies + "\n" + "Supports VBScript = " + browser.VBScript + "\n" + "Supports JavaScript = " + browser.EcmaScriptVersion.ToString() + "\n" + "Supports Java Applets = " + browser.JavaApplets + "\n" + "Supports ActiveX Controls = " + browser.ActiveXControls + "\n" ... }

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