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  • Design question?

    - by Mohamed
    I am building music app, where user can do several tasks including but not limited to listening song, like song, recommend song to a friend and extra. currently I have this model: class Activity(models.Model): activity = models.TextField() user = models.ForeignKey(User) date = models.DateTimeField(auto_now=True) so far I thought about two solutions. 1. saving a string to database. e.g "you listened song xyz" 2. create a dictionary about the activity and save to the database using pickle or json. e.g. dict_ = {"activity_type":"listening", "song":song_obj} I am leaning to the second implementation, but not quite sure. so what do you think about those two methods? do you know better way to achieve the goal?

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  • MVC 3 Nested EditorFor Templates

    - by Gordon Hickley
    I am working with MVC 3, Razor views and EditorFor templates. I have three simple nested models:- public class BillingMatrixViewModel { public ICollection<BillingRateRowViewModel> BillingRateRows { get; set; } public BillingMatrixViewModel() { BillingRateRows = new Collection<BillingRateRowViewModel>(); } } public class BillingRateRowViewModel { public ICollection<BillingRate> BillingRates { get; set; } public BillingRateRowViewModel() { BillingRates = new Collection<BillingRate>(); } } public class BillingRate { public int Id { get; set; } public int Rate { get; set; } } The BillingMatrixViewModel has a view:- @using System.Collections @using WIP_Data_Migration.Models.ViewModels @model WIP_Data_Migration.Models.ViewModels.BillingMatrixViewModel <table class="matrix" id="matrix"> <tbody> <tr> @Html.EditorFor(model => Model.BillingRateRows, "BillingRateRow") </tr> </tbody> </table> The BillingRateRow has an Editor Template called BillingRateRow:- @using System.Collections @model IEnumerable<WIP_Data_Migration.Models.ViewModels.BillingRateRowViewModel> @foreach (var item in Model) { <tr> <td> @item.BillingRates.First().LabourClass.Name </td> @Html.EditorFor(m => item.BillingRates) </tr> } The BillingRate has an Editor Template:- @model WIP_Data_Migration.Models.BillingRate <td> @Html.TextBoxFor(model => model.Rate, new {style = "width: 20px"}) </td> The markup produced for each input is:- <input name="BillingMatrix.BillingRateRows.item.BillingRates[0].Rate" id="BillingMatrix_BillingRateRows_item_BillingRates_0__Rate" style="width: 20px;" type="text" value="0"/> Notice the name and ID attributes the BillingRate indexes are handled nicely but the BillingRateRows has no index instead '.item.'. From my reasearch this is because the context has been pulled out due to the foreach loop, the loop shouldn't be necessary. I want to achieve:- <input name="BillingMatrix.BillingRateRows[0].BillingRates[0].Rate" id="BillingMatrix_BillingRateRows_0_BillingRates_0__Rate" style="width: 20px;" type="text" value="0"/> If I change the BillingRateRow View to:- @model WIP_Data_Migration.Models.ViewModels.BillingRateRowViewModel <tr> @Html.EditorFor(m => Model.BillingRates) </tr> It will throw an InvalidOperationException, 'model item passed into the dictionary is of type System.Collections.ObjectModel.Collection [BillingRateRowViewModel] but this dictionary required a type of BillingRateRowViewModel. Can anyone shed any light on this?

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  • Getting a random element in Django

    - by Sarah
    I just finished the Django tutorial and started work on my own project, however, I seem to have missed something completely. I wanted to get a random slogan from this model: from django.db import models class Slogan(models.Model): slogan = models.CharField(max_length=200) And return it in this view: from django.http import HttpResponse from swarm.sloganrotator.models import Slogan def index(request): return HttpResponse(Slogan.objects.order_by('?')[:1]) However, the view just returns 'Slogan object'. Then I thought, maybe I can access the slogan string itself by simply appending .slogan to the slice, but that gives me an error indicating that the object I have is actually a QuerySet and has no attribute slogan. I've obviously misunderstood something about Django here, but it just doesn't fall into place for me. Any help?

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  • Sorting related objects in the Django Admin form interface

    - by Carver
    I am looking to sort the related objects that show up when editing an object using the admin form. So for example, I would like to take the following object: class Person(models.Model): first_name = models.CharField( ... ) last_name = models.CharField( ... ) hero = models.ForeignKey( 'self', null=True, blank=True ) and edit the first name, last name and hero using the admin interface. I want to sort the objects as they show up in the drop down by last name, first name (ascending). How do I do that? Context I'm using Django v1.1. I started by looking for help in the django admin docs, but didn't find the solution As you can see in the example, the foreign key is pointing to itself, but I expect it would be the same as pointing to a different model object. Bonus points for being able to filter the related objects, too (eg~ only allow selecting a hero with the same first name)

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  • Django admin - remove field if editing an object

    - by John McCollum
    I have a model which is accessible through the Django admin area, something like the following: # model class Foo(models.Model): field_a = models.CharField(max_length=100) field_b = models.CharField(max_length=100) # admin.py class FooAdmin(admin.ModelAdmin): pass Let's say that I want to show field_a and field_b if the user is adding an object, but only field_a if the user is editing an object. Is there a simple way to do this, perhaps using the fields attribute? If if comes to it, I could hack a JavaScript solution, but it doesn't feel right to do that at all!

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  • Need help optimizing this Django aggregate query

    - by Chris Lawlor
    I have the following model class Plugin(models.Model): name = models.CharField(max_length=50) # more fields which represents a plugin that can be downloaded from my site. To track downloads, I have class Download(models.Model): plugin = models.ForiegnKey(Plugin) timestamp = models.DateTimeField(auto_now=True) So to build a view showing plugins sorted by downloads, I have the following query: # pbd is plugins by download - commented here to prevent scrolling pbd = Plugin.objects.annotate(dl_total=Count('download')).order_by('-dl_total') Which works, but is very slow. With only 1,000 plugins, the avg. response is 3.6 - 3.9 seconds (devserver with local PostgreSQL db), where a similar view with a much simpler query (sorting by plugin release date) takes 160 ms or so. I'm looking for suggestions on how to optimize this query. I'd really prefer that the query return Plugin objects (as opposed to using values) since I'm sharing the same template for the other views (Plugins by rating, Plugins by release date, etc.), so the template is expecting Plugin objects - plus I'm not sure how I would get things like the absolute_url without a reference to the plugin object. Or, is my whole approach doomed to failure? Is there a better way to track downloads? I ultimately want to provide users some nice download statistics for the plugins they've uploaded - like downloads per day/week/month. Will I have to calculate and cache Downloads at some point? EDIT: In my test dataset, there are somewhere between 10-20 Download instances per Plugin - in production I expect this number would be much higher for many of the plugins.

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  • Django - Expression based model constraints

    - by rtmie
    Is it possible to set an expression based constraint on a django model object, e.g. If I want to impose a constraint where an owner can have only one widget of a given type that is not in an expired state, but can have as many others as long as they are expired. Obviously I can do this by overriding the save method, but I am wondering if it can be done by setting constraints, e.g. some derivative of the unique_together constraint WIDGET_STATE_CHOICES = ( ('NEW', 'NEW'), ('ACTIVE', 'ACTIVE'), ('EXPIRED', 'EXPIRED') ) class MyWidget(models.Model): owner = models.CharField(max_length=64) widget_type = models.CharField(max_length = 10) widget_state = models.CharField(max_length = 10, choices = WIDGET_STATE_CHOICES) #I'd like to be able to do something like class Meta: unique_together = (("owner","widget_type","widget_state" != 'EXPIRED')

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  • filter queryset based on list, including None

    - by jujule
    Hi all I dont know if its a django bug or a feature but i have a strange ORM behaviour with MySQL. class Status(models.Model): name = models.CharField(max_length = 50) class Article(models.Model) status = models.ForeignKey(status, blank = True, null=True) filters = Q(status__in =[0, 1,2] ) | Q(status=None) items = Article.objects.filter(filters) this returns Article items but some have other status than requested [0,1,2,None] looking at the sql query : SELECT [..] FROM `app_article` LEFT OUTER JOIN `app_status` ON (`app_article`.`status_id` = `app_status`.`id`) WHERE (`app_article`.`status_id` IN (1, 2) OR `app_status`.`id` IS NULL) ORDER BY [...] the OR app_status.id IS NULL part seems to be the cause. if i change it to OR app_article.status_id IS NULL it works correctly. How to deal with this ? Thanx.

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  • best way to create tables with ORM?

    - by ajsie
    assume that i start coding an application from scratch, is the best way to create tables when using an ORM (doctrine), to manually create tables in mysql and then generate models from the tables, or is it the other way around, that is to create the models in php and then generate tables from models? and if i already have a database, will the models created be optimal? cause i have heard some say that its best to create the database from scratch when using ORM, so that the relations are optimized for OOD. share your thoughts!

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  • inheritance from the django user model results in error when changing password

    - by Jerome
    I inherited form the django user model like so: from django.db import models from django.contrib.auth.models import User, UserManager from django.utils.translation import ugettext_lazy as _ class NewUserModel(User): custom_field_1 = models.CharField(_('custom field 1'), max_length=250, null=True, blank=True) custom_field_2 = models.CharField(_('custom field 2'), max_length=250, null=True, blank=True) objects = UserManager() When i go to the admin and add an entry into this model, it saves fine, but below the "Password" field where it has this text "Use '[algo]$[salt]$[hexdigest]' or use the change password form.", if i click on the "change password form' link, it produces this error Truncated incorrect DOUBLE value: '7/password' What can i do to fix this?

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  • How can I use edit_in_place in the show of a different model in Rails?

    - by Angela
    I have a model Campaign and the campaign/show goes through a loop of the Emails. Campaign has_many Emails. <h2>Emails to Send Today</h2> <% for email in @campaign.emails %> <p><strong>Email: </strong><%= link_to email.title, email_path(email) %> sent after <%= distance_of_time_in_words(email.days.days) %></p> <% end %> I would like to be able to edit in place the subject and/or the email.days value from the Campaign/show page. How do I do that? (Added complexity, these are clickable links).

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  • How do I do a has_many through association on a has_many through association in rails?

    - by Angela
    Warning: I may have the wrong 'problem statement' but here it goes: A Campaign has many Contacts. A Campaign has many Emails. Therefore, a Contact has many Emails through a Campaign. And an Email can have many Contacts through a Campaign. Each Contact-Email pair has its own unique Status (status1, status2, etc). Each Status (for a Contact-Email pair) will have its own User. I do not know how to model Status, or User. Currently the immediate challenge is Status. (see diagram below)

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  • [Django] One single page to create a Parent object and its associated child objects

    - by ahmoo
    Hi all, This is my very first post on this awesome site, from which I have been finding answers to a handful of challenging questions. Kudos to the community! I am new to the Django world, so am hoping to find help from some Django experts here. Thanks in advance. Item model: class Item(models.Model): name = models.CharField(max_length=50) ItemImage model: class ItemImage(models.Model): image = models.ImageField(upload_to=get_unique_filename) item = models.ForeignKey(Item, related_name='images') As you can tell from the model definitions above, every Item object can have many ItemImage objects. My requirements are as followings: A single web page that allows users to create a new Item while uploading the images associated with the Item. The Item and the ItemImages objects should be created in the database all together, when the "Save" button on the page is clicked. I have created a variable in a custom config file, called NUMBER_OF_IMAGES_PER_ITEM. It is based on this variable that the system generates the number of image fields per item. Questions: What should the forms and the template be like? Can ModelForm be used to achieve the requirements? For the view function, what do I need to watch out other than making sure to save Item before ItemImage objects?

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  • reverse many to many fields in Django + count them

    - by cleliodpaula
    I'm trying to figure out how to solve this class Item(models.Model): type = models.ForeignKey(Type) name = models.CharField(max_lenght = 10) ... class List(models.Model): items = models.ManyToManyField(Item) ... I want to count how many an Item appears in another Lists, and show on template. view def items_by_list(request, id_): list = List.objects.get(id = id_) qr = list.items.all() #NOT TESTED num = [] i = 0 for item in qr: num[i] = List.objects.filter(items__id = item__id ).count() #FINISH NOT TESTED c = {} c.update(csrf(request)) c = {'request':request, 'list' : qr, 'num' : num} return render_to_response('items_by_list.html', c, context_instance=RequestContext(request)) template {% for dia in list %} <div class="span4" > <div> <h6 style="color: #9937d8">{{item.type.description}}</h6> <small style="color: #b2e300">{{ item.name }}</small> <small style="color: #b2e300">{{COUNT HOW MANY TIMES THE ITEM APPEAR ON OTHER LISTS}}</small> </div> {% endfor %} This seems to be easy, but I could not implement yet. If anyone has some glue to me, please help me. Thanks in advance.

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  • Filtering across two ManyToMany fields

    - by KVISH
    I have a User model and an Event model. I have the following for both: class Event(models.Model): ... timestamp = models.DateTimeField() organization_map = models.ManyToManyField(Organization) class User(AuthUser): ... subscribed_orgs = models.ManyToManyField('Organization') I want to find all events that were created in a certain timeframe and find the users who are subscribed to those organizations. I know how to write SQL for this (it's very easy), but whats the pythonic way of doing this using Django ORM? I'm trying as per below: orgs = Organization.objects.all() events = Event.objects.filter(timestamp__gt=min_time) # Min time is the time I want to start from events = events.filter(organization_map__in=orgs) But from there, how do I map to users who have that organization as a subscription? I'm trying to map it like so: users = User.objects.filter(subscribed_orgs__in=...

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  • Clarifying... So Background Jobs don't Tie Up Application Resources (in Rails)?

    - by viatropos
    I'm trying to get a better grasp of the inner workings of background jobs and how they improve performance. I understand that the goal is to have the application return a response to the user as fast as it can, so you don't want to, say, parse a huge feed that would take 10 seconds because it would prevent the application from being able to process any other requests. So it's recommended to put any operations that take more than say 500ms to execute, into a queued background job. What I don't understand is, doesn't that just delay the same problem? I know the user who invoked that background job will get an immediate response, but what if another user comes right when that background job starts (and it takes 10 seconds to finish), wont that user have to wait? Or is the main issue that, requests are the only thing that can happen one-at-a-time, while on the other hand a request can start while one+ background jobs are in the middle of running? Is that correct?

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  • How to exclude an array of ids from query in Rails (using ActiveRecord)?

    - by CuriousYogurt
    I would like to perform an ActiveRecord query that returns all records except those records that have certain ids. The ids I would like excluded are stored in an array. So: ids_to_exclude = [1,2,3] array_without_excluded_ids = Item. ??? I'm not sure how to complete the second line. Background: What I've already tried: I'm not sure background is necessary, but I've already tried various combinations of .find and .where. For example: array_without_excluded_ids = Item.find(:all, :conditions => { "id not IN (?)", ids_to_exclude }) array_without_excluded_ids = Item.where( "items.id not IN ?", ids_to_exclude) These fail. This tip might be on the right track, but I have not succeeded in adapting it. Any help would be greatly appreciated.

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  • Memcache on ubuntu server lucid and ruby 1.9.1

    - by Thiago
    Hi there, I'm trying to set up a memcache server on the above setup. I'm getting the following error: /var/lib/gems/1.9.1/gems/activesupport-2.3.8/lib/active_support/dependencies.rb:443:in `load_missing_constant': uninitialized constant MemCache (NameError) from /var/lib/gems/1.9.1/gems/activesupport-2.3.8/lib/active_support/dependencies.rb:80:in `const_missing_with_dependencies' from /var/lib/gems/1.9.1/gems/activesupport-2.3.8/lib/active_support/dependencies.rb:92:in `const_missing' from /root/voicegateway/vendor/plugins/workling/lib/workling/clients/memcache_queue_client.rb:18:in `<class:MemcacheQueueClient>' from /root/voicegateway/vendor/plugins/workling/lib/workling/clients/memcache_queue_client.rb:14:in `<module:Clients>' from /root/voicegateway/vendor/plugins/workling/lib/workling/clients/memcache_queue_client.rb:13:in `<module:Workling>' from /root/voicegateway/vendor/plugins/workling/lib/workling/clients/memcache_queue_client.rb:12:in `<top (required)>' from /var/lib/gems/1.9.1/gems/activesupport-2.3.8/lib/active_support/dependencies.rb:156:in `require' from /var/lib/gems/1.9.1/gems/activesupport-2.3.8/lib/active_support/dependencies.rb:156:in `block in require' from /var/lib/gems/1.9.1/gems/activesupport-2.3.8/lib/active_support/dependencies.rb:521:in `new_constants_in' from /var/lib/gems/1.9.1/gems/activesupport-2.3.8/lib/active_support/dependencies.rb:156:in `require' from /root/voicegateway/vendor/plugins/workling/lib/workling/remote/runners/client_runner.rb:2:in `<top (required)>' from /var/lib/gems/1.9.1/gems/activesupport-2.3.8/lib/active_support/dependencies.rb:156:in `require' from /var/lib/gems/1.9.1/gems/activesupport-2.3.8/lib/active_support/dependencies.rb:156:in `block in require' from /var/lib/gems/1.9.1/gems/activesupport-2.3.8/lib/active_support/dependencies.rb:521:in `new_constants_in' from /var/lib/gems/1.9.1/gems/activesupport-2.3.8/lib/active_support/dependencies.rb:156:in `require' from /root/voicegateway/vendor/plugins/workling/lib/workling/remote/runners/starling_runner.rb:1:in `<top (required)>' from /var/lib/gems/1.9.1/gems/activesupport-2.3.8/lib/active_support/dependencies.rb:156:in `require' from /var/lib/gems/1.9.1/gems/activesupport-2.3.8/lib/active_support/dependencies.rb:156:in `block in require' from /var/lib/gems/1.9.1/gems/activesupport-2.3.8/lib/active_support/dependencies.rb:521:in `new_constants_in' from /var/lib/gems/1.9.1/gems/activesupport-2.3.8/lib/active_support/dependencies.rb:156:in `require' from /root/voicegateway/vendor/plugins/workling/lib/workling/remote.rb:3:in `<top (required)>' from /var/lib/gems/1.9.1/gems/activesupport-2.3.8/lib/active_support/dependencies.rb:380:in `load' from /var/lib/gems/1.9.1/gems/activesupport-2.3.8/lib/active_support/dependencies.rb:380:in `block in load_file' from /var/lib/gems/1.9.1/gems/activesupport-2.3.8/lib/active_support/dependencies.rb:521:in `new_constants_in' from /var/lib/gems/1.9.1/gems/activesupport-2.3.8/lib/active_support/dependencies.rb:379:in `load_file' from /var/lib/gems/1.9.1/gems/activesupport-2.3.8/lib/active_support/dependencies.rb:259:in `require_or_load' from /var/lib/gems/1.9.1/gems/activesupport-2.3.8/lib/active_support/dependencies.rb:425:in `load_missing_constant' from /var/lib/gems/1.9.1/gems/activesupport-2.3.8/lib/active_support/dependencies.rb:80:in `const_missing_with_dependencies' from /root/voicegateway/config/environments/development.rb:20:in `block in load_environment' from /var/lib/gems/1.9.1/gems/rails-2.3.8/lib/initializer.rb:386:in `eval' from /var/lib/gems/1.9.1/gems/rails-2.3.8/lib/initializer.rb:386:in `block in load_environment' from /var/lib/gems/1.9.1/gems/activesupport-2.3.8/lib/active_support/core_ext/kernel/reporting.rb:11:in `silence_warnings' from /var/lib/gems/1.9.1/gems/rails-2.3.8/lib/initializer.rb:379:in `load_environment' from /var/lib/gems/1.9.1/gems/rails-2.3.8/lib/initializer.rb:137:in `process' from /var/lib/gems/1.9.1/gems/rails-2.3.8/lib/initializer.rb:113:in `run' from /root/voicegateway/config/environment.rb:9:in `<top (required)>' from /var/lib/gems/1.9.1/gems/activesupport-2.3.8/lib/active_support/dependencies.rb:156:in `require' from /var/lib/gems/1.9.1/gems/activesupport-2.3.8/lib/active_support/dependencies.rb:156:in `block in require' from /var/lib/gems/1.9.1/gems/activesupport-2.3.8/lib/active_support/dependencies.rb:521:in `new_constants_in' from /var/lib/gems/1.9.1/gems/activesupport-2.3.8/lib/active_support/dependencies.rb:156:in `require' from /var/lib/gems/1.9.1/gems/rails-2.3.8/lib/commands/server.rb:84:in `<top (required)>' from ./server:3:in `require' from ./server:3:in `<main>' But memcache-client 1.8.3 is on the gem list. What's the problem?

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  • Dependency injection with n-tier Entity Framework solution

    - by Matthew
    I am currently designing an n-tier solution which is using Entity Framework 5 (.net 4) as its data access strategy, but am concerned about how to incorporate dependency injection to make it testable / flexible. My current solution layout is as follows (my solution is called Alcatraz): Alcatraz.WebUI: An asp.net webform project, the front end user interface, references projects Alcatraz.Business and Alcatraz.Data.Models. Alcatraz.Business: A class library project, contains the business logic, references projects Alcatraz.Data.Access, Alcatraz.Data.Models Alcatraz.Data.Access: A class library project, houses AlcatrazModel.edmx and AlcatrazEntities DbContext, references projects Alcatraz.Data.Models. Alcatraz.Data.Models: A class library project, contains POCOs for the Alcatraz model, no references. My vision for how this solution would work is the web-ui would instantiate a repository within the business library, this repository would have a dependency (through the constructor) of a connection string (not an AlcatrazEntities instance). The web-ui would know the database connection strings, but not that it was an entity framework connection string. In the Business project: public class InmateRepository : IInmateRepository { private string _connectionString; public InmateRepository(string connectionString) { if (connectionString == null) { throw new ArgumentNullException("connectionString"); } EntityConnectionStringBuilder connectionBuilder = new EntityConnectionStringBuilder(); connectionBuilder.Metadata = "res://*/AlcatrazModel.csdl|res://*/AlcatrazModel.ssdl|res://*/AlcatrazModel.msl"; connectionBuilder.Provider = "System.Data.SqlClient"; connectionBuilder.ProviderConnectionString = connectionString; _connectionString = connectionBuilder.ToString(); } public IQueryable<Inmate> GetAllInmates() { AlcatrazEntities ents = new AlcatrazEntities(_connectionString); return ents.Inmates; } } In the Web UI: IInmateRepository inmateRepo = new InmateRepository(@"data source=MATTHEW-PC\SQLEXPRESS;initial catalog=Alcatraz;integrated security=True;"); List<Inmate> deathRowInmates = inmateRepo.GetAllInmates().Where(i => i.OnDeathRow).ToList(); I have a few related questions about this design. 1) Does this design even make sense in terms of Entity Frameworks capabilities? I heard that Entity framework uses the Unit-of-work pattern already, am I just adding another layer of abstract unnecessarily? 2) I don't want my web-ui to directly communicate with Entity Framework (or even reference it for that matter), I want all database access to go through the business layer as in the future I will have multiple projects using the same business layer (web service, windows application, etc.) and I want to have it easy to maintain / update by having the business logic in one central area. Is this an appropriate way to achieve this? 3) Should the Business layer even contain repositories, or should that be contained within the Access layer? If where they are is alright, is passing a connection string a good dependency to assume? Thanks for taking the time to read!

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  • Tips on ensuring Model Quality

    - by [email protected]
    Given enough data that represents well the domain and models that reflect exactly the decision being optimized, models usually provide good predictions that ensure lift. Nevertheless, sometimes the modeling situation is less than ideal. In this blog entry we explore the problems found in a few such situations and how to avoid them.1 - The Model does not reflect the problem you are trying to solveFor example, you may be trying to solve the problem: "What product should I recommend to this customer" but your model learns on the problem: "Given that a customer has acquired our products, what is the likelihood for each product". In this case the model you built may be too far of a proxy for the problem you are really trying to solve. What you could do in this case is try to build a model based on the result from recommendations of products to customers. If there is not enough data from actual recommendations, you could use a hybrid approach in which you would use the [bad] proxy model until the recommendation model converges.2 - Data is not predictive enoughIf the inputs are not correlated with the output then the models may be unable to provide good predictions. For example, if the input is the phase of the moon and the weather and the output is what car did the customer buy, there may be no correlations found. In this case you should see a low quality model.The solution in this case is to include more relevant inputs.3 - Not enough cases seenIf the data learned does not include enough cases, at least 200 positive examples for each output, then the quality of recommendations may be low. The obvious solution is to include more data records. If this is not possible, then it may be possible to build a model based on the characteristics of the output choices rather than the choices themselves. For example, instead of using products as output, use the product category, price and brand name, and then combine these models.4 - Output leaking into input giving the false impression of good quality modelsIf the input data in the training includes values that have changed or are available only because the output happened, then you will find some strong correlations between the input and the output, but these strong correlations do not reflect the data that you will have available at decision (prediction) time. For example, if you are building a model to predict whether a web site visitor will succeed in registering, and the input includes the variable DaysSinceRegistration, and you learn when this variable has already been set, you will probably see a big correlation between having a Zero (or one) in this variable and the fact that registration was successful.The solution is to remove these variables from the input or make sure they reflect the value as of the time of decision and not after the result is known. 

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  • Which web framework to use under Backbonejs?

    - by egidra
    For a previous project, I was using Backbonejs alongside Django, but I found out that I didn't use many features from Django. So, I am looking for a lighter framework to use underneath a Backbonejs web app. I never used Django built in templates. When I did, it was to set up the initial index page, but that's all. I did use the user management system that Django provided. I used the models.py, but never views.py. I used urls.py to set up which template the user would hit upon visiting the site. I noticed that the two features that I used most from Django was South and Tastypie, and they aren't even included with Django. Particularly, django-tastypie made it easy for me to link up my frontend models to my backend models. It made it easy to JSONify my front end models and send them to Tastypie. Although, I found myself overriding a lot of tastypie's methods for GET, PUT, POST requests, so it became useless. South made it easy to migrate new changes to the database. Although, I had so much trouble with South. Is there a framework with an easier way of handling database modifications than using South? When using South with multiple people, we had the worse time keeping our databases synced. When someone added a new table and pushed their migration to git, the other two people would spend days trying to use South's automatic migration, but it never worked. I liked how Rails had a manual way of migrating databases. Even though I used Tastypie and South a lot, I found myself not actually liking them because I ended up overriding most Tastypie methods for each Resource, and I also had the worst trouble migrating new tables and columns with South. So, I would like a framework that makes that process easier. Part of my problem was that they are too "magical". Which framework should I use? Nodejs or a lighter Python framework? Which works best with my above criteria?

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  • Given the presentation model pattern, is the view, presentation model, or model responsible for adding child views to an existing view at runtime?

    - by Ryan Taylor
    I am building a Flex 4 based application using the presentation model design pattern. This application will have several different components to it as shown in the image below. The MainView and DashboardView will always be visible and they each have corresponding presentation models and models as necessary. These views are easily created by declaring their MXML in the application root. <s:HGroup width="100%" height="100%"> <MainView width="75% height="100%"/> <DashboardView width="25%" height="100%"/> </s:HGroup> There will also be many WidgetViewN views that can be added to the DashboardView by the user at runtime through a simple drop down list. This will need to be accomplished via ActionScript. The drop down list should always show what WidgetViewN has already been added to the DashboardView. Therefore some state about which WidgetViewN's have been created needs to be stored. Since the list of available WidgetViewN and which ones are added to the DashboardView also need to be accessible from other components in the system I think this needs to be stored in a Model object. My understanding of the presentation model design pattern is that the view is very lean. It contains as close to zero logic as is practical. The view communicates/binds to the presentation model which contains all the necessary view logic. The presentation model is effectively an abstract representation of the view which supports low coupling and eases testability. The presentation model may have one or more models injected in in order to display the necessary information. The models themselves contain no view logic whatsoever. So I have a several questions around this design. Who should be responsible for creating the WidgetViewN components and adding these to the DashboardView? Is this the responsibility of the DashboardView, DashboardPresentationModel, DashboardModel or something else entirely? It seems like the DashboardPresentationModel would be responsible for creating/adding/removing any child views from it's display but how do you do this without passing in the DashboardView to the DashboardPresentationModel? The list of available and visible WidgetViewN components needs to be accessible to a few other components as well. Is it okay for a reference to a WidgetViewN to be stored/referenced in a model? Are there any good examples of the presentation model pattern online in Flex that also include creating child views at runtime?

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  • SQL Developer Data Modeler v3.3 Early Adopter: Link Model Objects Across Designs

    - by thatjeffsmith
    The third post in our “What’s New in SQL Developer Data Modeler v3.3” series, SQL Developer Data Modeler now allows you to link objects across models. If you need to catch up on the earlier posts, here are the first two: New and Improved Search Collaborative Design via Excel Today’s post is a very simple and straightforward discussion on how to share objects across models and designs. In previous releases you could easily copy and paste objects between models and designs. Simply select your object, right-click and select ‘Copy’ Once copied, paste it into your other designs and then make changes as required. Once you paste the object, it is no longer associated with the source it was copied from. You are free to make any changes you want in the new location without affecting the source material. And it works the other way as well – make any changes to the source material and the new object is also unaffected. However. What if you want to LINK a model object instead of COPYING it? In version 3.3, you can now do this. Simply drag and drop the object instead of copy and pasting it. Select the object, in this case a relational model table, and drag it to your other model. It’s as simple as it sounds, here’s a little animated GIF to show you what I’m talking about. Drag and drop between models/designs to LINK an object Notes The ‘linked’ object cannot be modified from the destination space Updating the source object will propagate the changes forward to wherever it’s been linked You can drag a linked object to another design, so dragging from A - B and then from B - C will work Linked objects are annotated in the model with a ‘Chain’ bitmap, see below This object has been linked from another design/model and cannot be modified. A very simple feature, but I like the flexibility here. Copy and paste = new independent object. Drag and drop = linked object.

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