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  • MVC (model-view-controller) - can it be explained in simple terms?

    - by DVK
    I need to explain to a not-very-technical manager the MVC (model-view-controller) concept and ran into trouble. The problem is that the explanation needs to be on a "your grandma will get it" level - e.g. even the fairly straightforward explanation offered on MVC Wiki page didn't work, at least with my commentary. Does anyone have a reference to a good MVC explanation in simple terms? It would ideally be done with non-techie metaphor examples (e.g. similar to "Decorator pattern is like glasses") - one reason I failed was that all MVC examples I could come up with were development related. I once saw a list of pattern explanations but to the best of my memory MVC was not on it. Thanks!

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  • What is the state of model driven development in 2012?

    - by eriktheblond
    I haven't heard a lot of talk lately on model driven development, but some of my company's customers are using it. I know briefly what it is, but after trying to refresh my memory using Google I found that most of the information is from 2006-2007. Was it something that never really took off? More worryingly is the reason why the customers are asking: They want IEC 61508 complience. Is this actually a "not-so-good" idea that will live on simply because it is prescribed by a standard? I have too little experience to say if MDD is good idea or not (I'm guessing the right answer starts with "It depends"...), but the reasons for using it, that is standard complience, seems just wrong.

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  • CakePHP: How can I disable auto-increment on Model.id?

    - by tomws
    CakePHP 1.3.0, mysqli I have a model, Manifest, whose ID should be the unique number from a printed form. However, with Manifest.id set as the primary key, CakePHP is helping me by setting up auto-increment on the field. Is there a way to flag the field via schema.php and/or elsewhere to disable auto-increment? I need just a plain, old primary key without it. The only other solution I can imagine is adding on a separate manifest number field and changing foreign keys in a half dozen other tables. A bit wasteful and not as intuitive.

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  • What are the differences between MVP, Presentation Model, MVVM and MVC?

    - by Nicholas
    I have a pretty good idea how each of these patterns work some of the minor differences between them, but are they really all that different from each other? It seems to me that the Presenter, Presentation Model, ViewModel and Controller are essentially the same concept. Why couldn't I classify all of these concepts as controllers? I feel like it might simplify the entire idea a great deal. Can anyone give a clear description of their differences? I want to clarify that I do understand how the patterns work, and have implemented most of them in one technology or another. What I am really looking for is someone's experience with one of these patterns, and why they would not consider their ViewModel a controller for instance.

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  • Where does the data model go in a Prism app?

    - by HawkeyeJoeS
    I'm having trouble where to put our data model in our Prism app. Most, if not all or our data will be coming from web services and the web services are unique for each module. Unfortunately, there will be objects that need to be shared (such as a person/user object). I'm really torn about whether to add these services directly to the module, so that each is truly independent, or create a separate project to house the web service proxies and business entities. The modules are being built by different teams, but will all live in the same solution (and source control, of course).

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  • Add fields to Django ModelForm that aren't in the model

    - by Cyclic
    I have a model that looks like: class MySchedule(models.Model): start_datetime=models.DateTimeField() name=models.CharField('Name',max_length=75) With it comes its ModelForm: class MyScheduleForm(forms.ModelForm): startdate=forms.DateField() starthour=forms.ChoiceField(choices=((6,"6am"),(7,"7am"),(8,"8am"),(9,"9am"),(10,"10am"),(11,"11am"), (12,"noon"),(13,"1pm"),(14,"2pm"),(15,"3pm"),(16,"4pm"),(17,"5pm"), (18,"6pm" startminute=forms.ChoiceField(choices=((0,":00"),(15,":15"),(30,":30"),(45,":45")))),(19,"7pm"),(20,"8pm"),(21,"9pm"),(22,"10pm"),(23,"11pm"))) class Meta: model=MySchedule def clean(self): starttime=time(int(self.cleaned_data.get('starthour')),int(self.cleaned_data.get('startminute'))) return self.cleaned_data try: self.instance.start_datetime=datetime.combine(self.cleaned_data.get("startdate"),starttime) except TypeError: raise forms.ValidationError("There's a problem with your start or end date") Basically, I'm trying to break the DateTime field in the model into 3 more easily usable form fields -- a date picker, an hour dropdown, and a minute dropdown. Then, once I've gotten the three inputs, I reassemble them into a DateTime and save it to the model. A few questions: 1) Is this totally the wrong way to go about doing it? I don't want to create fields in the model for hours, minutes, etc, since that's all basically just intermediary data, so I'd like a way to break the DateTime field into sub-fields. 2) The difficulty I'm running into is when the startdate field is blank -- it seems like it never gets checked for non-blankness, and just ends up throwing up a TypeError later when the program expects a date and gets None. Where does Django check for blank inputs, and raise the error that eventually goes back to the form? Is this my responsibility? If so, how do I do it, since it doesn't evaluate clean_startdate() since startdate isn't in the model. 3) Is there some better way to do this with inheritance? Perhaps inherit the MyScheduleForm in BetterScheduleForm and add the fields there? How would I do this? (I've been playing around with it for over an hours and can't seem to get it) Thanks! [Edit:] Left off the return self.cleaned_data -- lost it in the copy/paste originally

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  • Custom DateTime model binder in Asp.net MVC

    - by Robert Koritnik
    I would like to write my own model binder for DateTime type. First of all I'd like to write a new attribute that I can attach to my model property like: [DateTimeFormat("d.M.yyyy")] public DateTime Birth { get; set,} This is the easy part. But the binder part is a bit more difficult. I would like to add a new model binder for type DateTime. I can either implement IModelBinder interface and write my own BindModel() method inherit from DefaultModelBinder and override BindModel() method My model has a property as seen above (Birth). So when the model tries to bind request data to this property, my model binder's BindModel(controllerContext, bindingContext) gets invoked. Everything ok, but. How do I get property attributes from controller/bindingContext, to parse my date correctly? How can I get to the PropertyDesciptor of property Birth? Edit Because of separation of concerns my model class is defined in an assembly that doesn't (and shouldn't) reference System.Web.MVC assembly. Setting custom binding (similar to Scott Hanselman's example) attributes is a no-go here.

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  • Explaining the forecasts from an ARIMA model

    - by Samik R.
    I am trying to explain to myself the forecasting result from applying an ARIMA model to a time-series dataset. The data is from the M1-Competition, the series is MNB65. For quick reference, I have a google doc spreadsheet with the data. I am trying to fit the data to an ARIMA(1,0,0) model and get the forecasts. I am using R. Here are some output snippets: > arima(x, order = c(1,0,0)) Series: x ARIMA(1,0,0) with non-zero mean Call: arima(x = x, order = c(1, 0, 0)) Coefficients: ar1 intercept 0.9421 12260.298 s.e. 0.0474 202.717 > predict(arima(x, order = c(1,0,0)), n.ahead=12) $pred Time Series: Start = 53 End = 64 Frequency = 1 [1] 11757.39 11786.50 11813.92 11839.75 11864.09 11887.02 11908.62 11928.97 11948.15 11966.21 11983.23 11999.27 I have a few questions: (1) How do I explain that although the dataset shows a clear downward trend, the forecast from this model trends upward. This also happens for ARIMA(2,0,0), which is the best ARIMA fit for the data using auto.arima (forecast package) and for an ARIMA(1,0,1) model. (2) The intercept value for the ARIMA(1,0,0) model is 12260.298. Shouldn't the intercept satisfy the equation: C = mean * (1 - sum(AR coeffs)), in which case, the value should be 715.52. I must be missing something basic here. (3) This is clearly a series with non-stationary mean. Why is an AR(2) model still selected as the best model by auto.arima? Could there be an intuitive explanation? Thanks.

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  • Pass ng-model and place-holder value into directive

    - by Zen
    I have a segment of code needs to be reuse a lot, there for I want to just create a directive for it. <div class="btn-group"> <div class="input-group"> <div class="has-feedback"> <input type="text" class="form-control" placeholder="BLAH BLAH" ng-model="model"> <span class="times form-control-feedback" ng-click="model=''" ng-show="model.length > 0"></span> </div> </div> </div> I want to use this code as template in directive. Create a directive used as follow: <div search-Field ng-model="model" placeholder="STRING"></div> to replace to old html, ng-model and placeholder will be as variables. angular.module('searchField', []) .directive('searchField', [function () { return { scope: { placeholder: '@', ngModel: '=' }, templateUrl: 'Partials/_SearchInputGroup.html' } }]); Is it the way of doing it?

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  • How does Backbone.js connect View to Model

    - by William Sham
    I am trying to learn backbone.js through the following example. Then I got stuck at the point ItemView = Backbone.View.extend why you can use this.model.get? I thought this is referring to the instance of ItemView that would be created. Then why would ItemView has a model property at all?!! (function($){ var Item = Backbone.Model.extend({ defaults: { part1: 'hello', part2: 'world' } }); var List = Backbone.Collection.extend({ model: Item }); var ItemView = Backbone.View.extend({ tagName: 'li', initialize: function(){ _.bindAll(this, 'render'); }, render: function(){ $(this.el).html('<span>'+this.model.get('part1')+' '+this.model.get('part2')+'</span>'); return this; } }); var ListView = Backbone.View.extend({ el: $('body'), events: { 'click button#add': 'addItem' }, initialize: function(){ _.bindAll(this, 'render', 'addItem', 'appendItem'); this.collection = new List(); this.collection.bind('add', this.appendItem); this.counter = 0; this.render(); }, render: function(){ $(this.el).append("<button id='add'>Add list item</button>"); $(this.el).append("<ul></ul>"); _(this.collection.models).each(function(item){ appendItem(item); }, this); }, addItem: function(){ this.counter++; var item = new Item(); item.set({ part2: item.get('part2') + this.counter }); this.collection.add(item); }, appendItem: function(item){ var itemView = new ItemView({ model: item }); $('ul', this.el).append(itemView.render().el); } }); var listView = new ListView(); })(jQuery);

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  • Domain Models (PHP)

    - by Calum Bulmer
    I have been programming in PHP for several years and have, in the past, adopted methods of my own to handle data within my applications. I have built my own MVC, in the past, and have a reasonable understanding of OOP within php but I know my implementation needs some serious work. In the past I have used an is-a relationship between a model and a database table. I now know after doing some research that this is not really the best way forward. As far as I understand it I should create models that don't really care about the underlying database (or whatever storage mechanism is to be used) but only care about their actions and their data. From this I have established that I can create models of lets say for example a Person an this person object could have some Children (human children) that are also Person objects held in an array (with addPerson and removePerson methods, accepting a Person object). I could then create a PersonMapper that I could use to get a Person with a specific 'id', or to save a Person. This could then lookup the relationship data in a lookup table and create the associated child objects for the Person that has been requested (if there are any) and likewise save the data in the lookup table on the save command. This is now pushing the limits to my knowledge..... What if I wanted to model a building with different levels and different rooms within those levels? What if I wanted to place some items in those rooms? Would I create a class for building, level, room and item with the following structure. building can have 1 or many level objects held in an array level can have 1 or many room objects held in an array room can have 1 or many item objects held in an array and mappers for each class with higher level mappers using the child mappers to populate the arrays (either on request of the top level object or lazy load on request) This seems to tightly couple the different objects albeit in one direction (ie. a floor does not need to be in a building but a building can have levels) Is this the correct way to go about things? Within the view I am wanting to show a building with an option to select a level and then show the level with an option to select a room etc.. but I may also want to show a tree like structure of items in the building and what level and room they are in. I hope this makes sense. I am just struggling with the concept of nesting objects within each other when the general concept of oop seems to be to separate things. If someone can help it would be really useful. Many thanks

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  • Hadoop, NOSQL, and the Relational Model

    - by Phil Factor
    (Guest Editorial for the IT Pro/SysAdmin Newsletter)Whereas Relational Databases fit the world of commerce like a glove, it is useless to pretend that they are a perfect fit for all human endeavours. Although, with SQL Server, we’ve made great strides with indexing text, in processing spatial data and processing markup, there is still a problem in dealing efficiently with large volumes of ephemeral semi-structured data. Key-value stores such as Cassandra, Project Voldemort, and Riak are of great value for ephemeral data, and seem of equal value as a data-feed that provides aggregations to an RDBMS. However, the Document databases such as MongoDB and CouchDB are ideal for semi-structured data for which no fixed schema exists; analytics and logging are obvious examples. NoSQL products, such as MongoDB, tackle the semi-structured data problem with panache. MongoDB is designed with a simple document-oriented data model that scales horizontally across multiple servers. It doesn’t impose a schema, and relies on the application to enforce the data structure. This is another take on the old ‘EAV’ problem (where you don’t know in advance all the attributes of a particular entity) It uses a clever replica set design that allows automatic failover, and uses journaling for data durability. It allows indexing and ad-hoc querying. However, for SQL Server users, the obvious choice for handling semi-structured data is Apache Hadoop. There will soon be an ODBC Driver for Apache Hive .and an Add-in for Excel. Additionally, there are now two Hadoop-based connectors for SQL Server; the Apache Hadoop connector for SQL Server 2008 R2, and the SQL Server Parallel Data Warehouse (PDW) connector. We can connect to Hadoop process the semi-structured data and then store it in SQL Server. For one steeped in the culture of Relational SQL Databases, I might be expected to throw up my hands in the air in a gesture of contempt for a technology that was, judging by the overblown journalism on the subject, about to make my own profession as archaic as the Saggar makers bottom knocker (a potter’s assistant who helped the saggar maker to make the bottom of the saggar by placing clay in a metal hoop and bashing it). However, on the contrary, I find that I'm delighted with the advances made by the NoSQL databases in the past few years. Having the flow of ideas from the NoSQL providers will knock any trace of complacency out of the providers of Relational Databases and inspire them into back-fitting some features, such as horizontal scaling, with sharding and automatic failover into SQL-based RDBMSs. It will do the breed a power of good to benefit from all this lateral thinking.

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  • Should Business Interfaces be part of the Model layer?

    - by Mik378
    In an oriented-services enterprise application, isn't it an antipattern to mix Service APIs (containing interface that external users depends on) with Model objects (entities, custom exceptions objects etc...) ? According to me, Services should only depends on Model layer but never mixed with it. In fact, my colleague told me that it doesn't make sense to separate it since client need both. (model and service interfaces) But I notice that everytime a client asks for some changes, like adding a new method in some interface (means a new service), Model layer has to be also delivered... Thus, client who has not interested by this "addition" is constrained to be concerned by this update of Model... and in a large enterprise application, this kind of delivery is known to be very risked... What is the best practice ? Separate services(only interfaces so) and model objects or mix it ?

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  • Is there a way to customize how the value for a custom Model Field is displayed in a template?

    - by Jordan Reiter
    I am storing dates as an integer field in the format YYYYMMDD, where month or day is optional. I have the following function for formatting the number: def flexibledateformat(value): import datetime, re try: value = str(int(value)) except: return None match = re.match(r'(\d{4})(\d\d)(\d\d)$',str(value)) if match: year_val, month_val, day_val = [int(v) for v in match.groups()] if day_val: return datetime.datetime.strftime(datetime.date(year_val,month_val,day_val),'%b %e, %Y') elif month_val: return datetime.datetime.strftime(datetime.date(year_val,month_val,1),'%B %Y') else: return str(year_val) Which results in the following outputs: >>> flexibledateformat(20100415) 'Apr 15, 2010' >>> flexibledateformat(20100400) 'April 2010' >>> flexibledateformat(20100000) '2010' So I'm wondering if there's a function I can add under the model field class that would automatically call flexibledateformat. So if there's a record r = DataRecord(name='foo',date=20100400) when processed in the form the value would be 20100400 but when output in a template using {{ r.date }} it shows up as "April 2010". Further clarification I do normally use datetime for storing date/time values. In this specific case, I need to record non-specific dates: "x happened in 2009", "y happened sometime in June 1996". The easiest way to do this while still preserving most of the functionality of a date field, including sorting and filtering, is by using an integer in the format of yyyymmdd. That is why I am using an IntegerField instead of a DateTimeField. This is what I would like to happen: I store what I call a "Flexible Date" in a FlexibleDateField as an integer with the format yyyymmdd. I render a form that includes a FlexibleDateField, and the value remains an integer so that functions necessary for validating it and rendering it in widgets work correctly. I call it in a template, as in {{ object.flexibledate }} and it is formatted according to the flexibledateformat rules: 20100416 - April 16, 2010; 20100400 - April 2010; 20100000 - 2010. This also applies when I'm not calling it directly, such as when it's used as a header in admin (http://example.org/admin/app_name/model_name/). I'm not aware if these specific things are possible.

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  • [Database] How to model this one-to-one relation?

    - by pbean
    I have several entities which respresent different types of users who need to be able to log in to a particular system. Additionally, they have different types of information associated with them. For example: a "general user", which has an e-mail address and "admin user", which has a workstation number (note that this a hypothetical case). Both entities also share common properties like first name, surname, address and telephone number. Finally, they naturally need to have a (unique) user name and a password to log in. In the application, the user just has to fill in his user name and password, and the functionality of the application changes slightly according to the type of the user. You can imagine that the username needs to be unique for this work. How should I model this effectively? I can't just create two tables, because then I can't force a unique constaint on the user name. I also can't put them all in just one table, because they have different types of specific information associated to them. I think I might need 3 seperate tables, one for "users" (with user name and password), one for the "general users" and another one for the "admin users", but how would the relations between these work? Or is there another solution? (By the way, the target DBMS is MySQL, so I don't think generalization is supported in the database system itself).

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  • How to do an additional search on archive in rails if record not found, by extending model?

    - by Nick Gorbikoff
    Hello, I was wondering if somebody knows an elegant solution to the following: Suppose I have a table that holds orders, with a bunch of data. So I'm at 1M records, and searches begin to take time. So I want to speed it up by archiving some data that is more than 3 years old - saving it into a table called orders-archive, and then purging them from the orders table. So if we need to research something or customer wants to pull older information - they still can, but 99% of the lookups are done on the orders no older than a year and a half - so there is no reason to keep looking through older data all the time. These move & purge operations can be then croned to be done on a weekly basis. I already did some tests and I know that I will slash my search times by about 4 times. So far so good, right? However I was thinking about how to implement older archival lookups and the only reasonable thing I can think of is some sort of if-else If not found in orders, do a search in orders-archive. However - I have about 20 tables that I want to archive and god knows how many searches / finds are done through out the code, that I don't want to modify. So I was wondering if there is an elegant rails-way solution to this problem, by extending a model somehow? Has anyone dealt with similar case before? Thank you.

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  • What do you call a generalized (non-GUI-related) "Model-View-Controller" architecture?

    - by dcuccia
    I am currently refactoring code that coordinates multiple hardware components for data acquisition, and feeling a bit like I'm recreating the wheel. In particular, an MVC-like pattern seems to be emerging. Except, this has nothing to do with a GUI and I'm worried that I'm forcing this particular pattern where another might be more appropriate. Here's my scenario: Individual hardware "component" classes obey interface contracts for each hardware type. Previously, component instances were orchestrated by a single monolithic InstrumentController class, which relied heavily on configuration + branching logic for executing a specific acquisition sequence. After an iteration, I have a separate controller for each component, with these controllers all managed by a small InstrumentControllerBase (or its derivatives). The composite system will receive "input" either programmatically or via inter-hardware component triggering - in either case these interactions are routed to, and handled by, the appropriate controller. So, I have something that feels MVC-esque, but I don't know if that's because I'm forcing the point. With little direct MVC experience in application development, it's hard to know if I'm just trying to make my scenario fit MVC, where another pattern might be a good alternative or complimentary. My problem is, search results and wiki documentation of these family of patterns seems to immediately drop me into GUI-specific discussions. I understand "M means Model data and the V means View" - but do you call the superset pattern? Component-Commander-Controller? Whence can I exhume examples exemplary?

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  • integrating tinymce with asp .net MVC 4.0

    - by user1865670
    using ASP .NET MVC 4.0 , VS2012. In one of my page, I tried to integrate a WYSIWYG editor "TinyMCE". To integrate, I followed the following URL : .tugberkugurlu.com My view page is like : @model AboutModels @using FileUploadDemo.Models <script src="https://ajax.googleapis.com/ajax/libs/jquery/1.7.2/jquery.js"></script> <script src="https://ajax.googleapis.com/ajax/libs/jquery/1.7.2/jquery.min.js"></script> <script src="Scripts/tinymce/jquery.tinymce.js" type="text/javascript"></script> @{ ViewBag.Title = "About"; } @using (Html.BeginForm()) { @Html.ValidationSummary(true) <fieldset> <legend>About</legend> <div class="editor-label"> @Html.LabelFor(model => model.Title) </div> <div class="editor-field"> @Html.EditorFor(model => model.Title) @Html.ValidationMessageFor(model => model.Title) </div> <div class="editor-label"> @Html.LabelFor(model => model.PostedOn) </div> <div class="editor-field"> @Html.EditorFor(model => model.PostedOn) @Html.ValidationMessageFor(model => model.PostedOn) </div> <div class="editor-label"> @Html.LabelFor(model => model.Tags) </div> <div class="editor-field"> @Html.EditorFor(model => model.Tags) @Html.ValidationMessageFor(model => model.Tags) </div> <div class="editor-label"> @Html.LabelFor(model => model.Content) </div> <div class="editor-field"> @Html.EditorFor(model => model.Content) @Html.ValidationMessageFor(model => model.Content) </div> <p> <input type="submit" value="Create" /> </p> <p> Posted Content : @ViewBag.HtmlContent </p> </fieldset> } Here my Model is like : public class AboutModels { public string Title { get; set; } public DateTime PostedOn { get; set; } public string Tags { get; set; } [UIHint("tinymce_jquery_full"), AllowHtml] public string Content { get; set; } } My about page loads with all features. "@html.EditorFor(model=>model.content)" also loads fine. but no "WYSIWYG" pane(i donno what it is called, the pane is used to edit my text written in the textarea(HTml.editorFor())) is loaded. In the runtime, Exception is thrown in jquery.tinymce.js file. Error Message : `Unhandled exception at line 86, column 11 in http://localhost:1706/Home/About 0x800a01b6 - Microsoft JScript runtime error: Object doesn't support this property or method` And give me two options, Continue or Break . If i continue, the page loads with features as i mentioned earlier. If i Break, then it stays in the jquery.tinymce.js file with a yellow text-background. I have no experience with Javascript/jquery. And new in ASP .NET MVC 4.0, actually this is my first try of web application in .net. I updated jquery from nuGet. What could be the possible ways to solve it?

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  • Example of an ASP.NET MVC post model?

    - by Anthony Potts
    I was watching the HaHaa presentation on ASP.NET MVC from MIX and they mentioned using a Post Model where I guess they were saying you could use a model that was ONLY for posting. I have tried looking for examples for this. Am I not understanding what they are saying? Does anyone have an example of how this might work in a strongly typed view where the view model and post model are not of the same type?

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  • Django User model, adding function

    - by Hellnar
    Hello, I want to add a new function to the default User model of Django for retrieveing a related list of Model type. Such Foo model: class Foo(models.Model): owner = models.ForeignKey(User, related_name="owner") likes = models.ForeignKey(User, related_name="likes") ........ #at some view user = request.user foos= user.get_related_foo_models() Hwo can this be achieved ?

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  • Options for keeping models and the UI in sync (in a desktop application context)

    - by Benju
    In my experience I have only had 2 patterns work for large-scale desktop application development when trying to keep the model and UI in sync. 1-An eventbus approach via a shared eventbus command objects are fired (ie:UserDemographicsUpdatedEvent) and have various parts of the UI update if they are bound to the same user object updated in this event. 2-Attempt to bind the UI directly to the model adding listeners to the model itself as needed. I find this approach rather clunky as it pollutes the domain model. Does anybody have other suggestions? In a web application with something like JSP binding to the model is easy as you ussually only care about the state of the model at the time your request comes in, not so in a desktop type application. Any ideas?

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  • C#: Inheritance, Overriding, and Hiding

    - by Rosarch
    I'm having difficulty with an architectural decision for my C# XNA game. The basic entity in the world, such as a tree, zombie, or the player, is represented as a GameObject. Each GameObject is composed of at least a GameObjectController, GameObjectModel, and GameObjectView. These three are enough for simple entities, like inanimate trees or rocks. However, as I try to keep the functionality as factored out as possible, the inheritance begins to feel unwieldy. Syntactically, I'm not even sure how best to accomplish my goals. Here is the GameObjectController: public class GameObjectController { protected GameObjectModel model; protected GameObjectView view; public GameObjectController(GameObjectManager gameObjectManager) { this.gameObjectManager = gameObjectManager; model = new GameObjectModel(this); view = new GameObjectView(this); } public GameObjectManager GameObjectManager { get { return gameObjectManager; } } public virtual GameObjectView View { get { return view; } } public virtual GameObjectModel Model { get { return model; } } public virtual void Update(long tick) { } } I want to specify that each subclass of GameObjectController will have accessible at least a GameObjectView and GameObjectModel. If subclasses are fine using those classes, but perhaps are overriding for a more sophisticated Update() method, I don't want them to have to duplicate the code to produce those dependencies. So, the GameObjectController constructor sets those objects up. However, some objects do want to override the model and view. This is where the trouble comes in. Some objects need to fight, so they are CombatantGameObjects: public class CombatantGameObject : GameObjectController { protected new readonly CombatantGameModel model; public new virtual CombatantGameModel Model { get { return model; } } protected readonly CombatEngine combatEngine; public CombatantGameObject(GameObjectManager gameObjectManager, CombatEngine combatEngine) : base(gameObjectManager) { model = new CombatantGameModel(this); this.combatEngine = combatEngine; } public override void Update(long tick) { if (model.Health <= 0) { gameObjectManager.RemoveFromWorld(this); } base.Update(tick); } } Still pretty simple. Is my use of new to hide instance variables correct? Note that I'm assigning CombatantObjectController.model here, even though GameObjectController.Model was already set. And, combatants don't need any special view functionality, so they leave GameObjectController.View alone. Then I get down to the PlayerController, at which a bug is found. public class PlayerController : CombatantGameObject { private readonly IInputReader inputReader; private new readonly PlayerModel model; public new PlayerModel Model { get { return model; } } private float lastInventoryIndexAt; private float lastThrowAt; public PlayerController(GameObjectManager gameObjectManager, IInputReader inputReader, CombatEngine combatEngine) : base(gameObjectManager, combatEngine) { this.inputReader = inputReader; model = new PlayerModel(this); Model.Health = Constants.PLAYER_HEALTH; } public override void Update(long tick) { if (Model.Health <= 0) { gameObjectManager.RemoveFromWorld(this); for (int i = 0; i < 10; i++) { Debug.WriteLine("YOU DEAD SON!!!"); } return; } UpdateFromInput(tick); // .... } } The first time that this line is executed, I get a null reference exception: model.Body.ApplyImpulse(movementImpulse, model.Position); model.Position looks at model.Body, which is null. This is a function that initializes GameObjects before they are deployed into the world: public void Initialize(GameObjectController controller, IDictionary<string, string> data, WorldState worldState) { controller.View.read(data); controller.View.createSpriteAnimations(data, _assets); controller.Model.read(data); SetUpPhysics(controller, worldState, controller.Model.BoundingCircleRadius, Single.Parse(data["x"]), Single.Parse(data["y"]), bool.Parse(data["isBullet"])); } Every object is passed as a GameObjectController. Does that mean that if the object is really a PlayerController, controller.Model will refer to the base's GameObjectModel and not the PlayerController's overriden PlayerObjectModel? In response to rh: This means that now for a PlayerModel p, p.Model is not equivalent to ((CombatantGameObject)p).Model, and also not equivalent to ((GameObjectController)p).Model. That is exactly what I do not want. I want: PlayerController p; p.Model == ((CombatantGameObject)p).Model p.Model == ((GameObjectController)p).Model How can I do this? override?

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  • Replace textfields with dropdown select fields

    - by 47
    I have three model classes that look as below: class Model(models.Model): model = models.CharField(max_length=20, blank=False) manufacturer = models.ForeignKey(Manufacturer) date_added = models.DateField(default=datetime.today) def __unicode__(self): name = ''+str(self.manufacturer)+" "+str(self.model) return name class Series(models.Model): series = models.CharField(max_length=20, blank=True, null=True) model = models.ForeignKey(Model) date_added = models.DateField(default=datetime.today) def __unicode__(self): name = str(self.model)+" "+str(self.series) return name class Manufacturer(models.Model): MANUFACTURER_POPULARITY_CHOICES = ( ('1', 'Primary'), ('2', 'Secondary'), ('3', 'Tertiary'), ) manufacturer = models.CharField(max_length=15, blank=False) date_added = models.DateField(default=datetime.today) manufacturer_popularity = models.CharField(max_length=1, choices=MANUFACTURER_POPULARITY_CHOICES) def __unicode__(self): return self.manufacturer I want to have the fields for model series and manufacturer represented as dropdowns instead of text fields. I have customized the model forms as below: class SeriesForm(ModelForm): series = forms.ModelChoiceField(queryset=Series.objects.all()) class Meta: model = Series exclude = ('model', 'date_added',) class ModelForm(ModelForm): model = forms.ModelChoiceField(queryset=Model.objects.all()) class Meta: model = Model exclude = ('manufacturer', 'date_added',) class ManufacturerForm(ModelForm): manufacturer = forms.ModelChoiceField(queryset=Manufacturer.objects.all()) class Meta: model = Manufacturer exclude = ('date_added',) However, the dropdowns are populated with the unicode in the respective class...how can I further customize this to get the end result I want? Also, how can I populate the forms with the correct data for editing? Currently only SeriesForm is populated. The starting point of all this is from another class whose declaration is as below: class CommonVehicle(models.Model): year = models.ForeignKey(Year) series = models.ForeignKey(Series) .... def __unicode__(self): name = ''+str(self.year)+" "+str(self.series) return name

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  • Event sourcing: Write event before or after updating the model

    - by Magnus
    I'm reasoning about event sourcing and often I arrive at a chicken and egg problem. Would be grateful for some hints on how to reason around this. If I execute all I/O-bound processing async (ie writing to the event log) then how do I handle, or sometimes even detect, failures? I'm using Akka Actors so processing is sequential for each event/message. I do not have any database at this time, instead I would persist all the events in an event log and then keep an aggregated state of all the events in a model stored in memory. Queries are all against this model, you can consider it to be a cache. Example Creating a new user: Validate that the user does not exist in model Persist event to journal Update model (in memory) If step 3 breaks I still have persisted my event so I can replay it at a later date. If step 2 breaks I can handle that as well gracefully. This is fine, but since step 2 is I/O-bound I figured that I should do I/O in a separate actor to free up the first actor for queries: Updating a user while allowing queries (A0 = Front end/GUI actor, A1 = Processor Actor, A2 = IO-actor, E = event bus). (A0-E-A1) Event is published to update user 'U1'. Validate that the user 'U1' exists in model (A1-A2) Persist event to journal (separate actor) (A0-E-A1-A0) Query for user 'U1' profile (A2-A1) Event is now persisted continue to update model (A0-E-A1-A0) Query for user 'U1' profile (now returns fresh data) This is appealing since queries can be processed while I/O-is churning along at it's own pace. But now I can cause myself all kinds of problems where I could have two incompatible commands (delete and then update) be persisted to the event log and crash on me when replayed up at a later date, since I do the validation before persisting the event and then update the model. My aim is to have a simple reasoning around my model (since Actor processes messages sequentially single threaded) but not be waiting for I/O-bound updates when Querying. I get the feeling I'm modeling a database which in itself is might be a problem. If things are unclear please write a comment.

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  • backbone model validation error

    - by koko
    I got a validation based on backbone fundamentals by addyosmani, but when i try it on my view i can't get the error that the model generated.TIA model.js validate: function(attrs) { var errors = this.errors = {}; if (!attrs.box) errors.box= 'box value is required'; //console.log(errors.box); if (!_.isEmpty(errors)) return errors; } view.js validate: function(model) { console.log("error text--" + model.errors[this.input] || ''); },

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