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  • Model format for small game

    - by DeadMG
    I'm writing my own small-time game from scratch, and now I'm looking to start creating models. I've been wondering- what is the best model format to use? Given that I will be writing the model loading code myself and using whatever program generates them. Ideally, I'd look for a format that has fairly wide support between modelling programs, so I can pick the one I like most to actually perform the building, and the format itself would be relatively simple to load, rather than having all of the latest features.

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  • Backbone.js Model validation fails to prevent Model from saving

    - by Benjen
    I have defined a validate method for a Backbone.js Model. The problem is that even if validation fails (i.e. the Model.validate method returns a value) the post/put request is still sent to the server. This contradicts what is explained in the Backbone.js documentation. I cannot understand what I am doing wrong. The following is the Model definition: /** * Model - Contact */ var Contact = Backbone.Model.extend({ urlRoot: '/contacts.json', idAttribute: '_id', defaults: function() { return { surname: '', given_name: '', org: '', phone: new Array(), email: new Array(), address: new Array({ street: '', district: '', city: '', country: '', postcode: '' }) }; } validate: function(attributes) { if (typeof attributes.validationDisabled === 'undefined') { var errors = new Array(); // Validate surname. if (_.isEmpty(attributes.surname) === true) { errors.push({ type: 'form', attribute: 'surname', message: 'Please enter a surname.' }); } // Validate emails. if (_.isEmpty(attributes.email) === false) { var emailRegex = /^[a-z0-9._%+-]+@[a-z0-9.-]+\.[a-z]{2,6}$/i; // Stores indexes of email values which fail validation. var emailIndex = new Array(); _.each(attributes.email, function(email, index) { if (emailRegex.test(email.value) === false) { emailIndex.push(index); } }); // Create error message. if (emailIndex.length > 0) { errors.push({ type: 'form', attribute: 'email', index: emailIndex, message: 'Please enter valid email address.' }); } } if (errors.length > 0) { console.log('Form validation failed.'); return errors; } } } }); Here is the View which calls the Model.save() method (see: method saveContact() below). Note that other methods belonging to this View have not been included below for reasons of brevity. /** * View - Edit contact form */ var EditContactFormView = Backbone.View.extend({ initialize: function() { _.bindAll(this, 'createDialog', 'formError', 'render', 'saveContact', 'updateContact'); // Add templates. this._editFormTemplate = _.template($('#edit-contact-form-tpl').html()); this._emailFieldTemplate = _.template($('#email-field-tpl').html()); this._phoneFieldTemplate = _.template($('#phone-field-tpl').html()); // Get URI of current page. this.currentPageUri = this.options.currentPageUri; // Create array to hold references to all subviews. this.subViews = new Array(); // Set options for new or existing contact. this.model = this.options.model; // Bind with Model validation error event. this.model.on('error', this.formError); this.render(); } /** * Deals with form validation errors */ formError: function(model, error) { console.log(error); }, saveContact: function(event) { var self = this; // Prevent submit event trigger from firing. event.preventDefault(); // Trigger form submit event. eventAggregator.trigger('submit:contactEditForm'); // Update model with form values. this.updateContact(); // Enable validation for Model. Done by unsetting validationDisabled // attribute. This setting was formerly applied to prevent validation // on Model.fetch() events. See this.model.validate(). this.model.unset('validationDisabled'); // Save contact to database. this.model.save(this.model.attributes, { success: function(model, response) { if (typeof response.flash !== 'undefined') { Messenger.trigger('new:messages', response.flash); } }, error: function(model, response) { console.log(response); throw error = new Error('Error occured while trying to save contact.'); } }, { wait: true }); }, /** * Extract form values and update Contact. */ updateContact: function() { this.model.set('surname', this.$('#surname-field').val()); this.model.set('given_name', this.$('#given-name-field').val()); this.model.set('org', this.$('#org-field').val()); // Extract address form values. var address = new Array({ street: this.$('input[name="street"]').val(), district: this.$('input[name="district"]').val(), city: this.$('input[name="city"]').val(), country: this.$('input[name="country"]').val(), postcode: this.$('input[name="postcode"]').val() }); this.model.set('address', address); } });

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  • Ruby on Rails Join Table Associations

    - by Eef
    Hey, I have a Ruby on Rails application setup like so: User Model has_and_belongs_to_many :roles Role Model has_many :transactions has_and_belongs_to_many :users Transaction Model belongs_to :role This means that a join table is used called roles_users and it also means that a user can only see the transactions that have been assigned to them through roles, usage example: user = User.find(1) transactions = user.roles.first.transactions This will return the transactions which are associated with the first role assigned to the user. If a user has 2 roles assigned to them, at the moment to get the transactions associated with the second role I would do: transactions = user.roles.last.transactions I am basically trying to figure out a way to setup an association so I can grab the user's transactions via something like this based on the roles defined in the association between the user and roles: user = User.find(1) transactions = user.transactions I am not sure if this is possible? I hope you understand what I am trying to do.

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  • CIC 2010 - Ghost Stories and Model Based Design

    - by warren.baird
    I was lucky enough to attend the collaboration and interoperability congress recently. The location was very beautiful and interesting, it was held in the mountains about two hours outside Denver, at the Stanley hotel, famous both for inspiring Steven King's novel "The Shining" and for attracting a lot of attention from the "Ghost Hunters" TV show. My visit was prosaic - I didn't get to experience the ghosts the locals promised - but interesting, with some very informative sessions. I noticed one main theme - a lot of people were talking about Model Based Design (MBD), which is moving design and manufacturing away from 2d drawings and towards 3d models. 2d has some pretty deep roots in industrial manufacturing and there have been a lot of challenges encountered in making the leap to 3d. One of the challenges discussed in several sessions was how to get model information out to the non-engineers in the company, which is a topic near and dear to my heart. In the 2D space, people without access to CAD software (for example, people assembling a product on the shop floor) can be given printouts of the design - it's not particularly efficient, and it definitely isn't very green, but it tends to work. There's no direct equivalent in the 3D space. One of the ways that AutoVue is used in industrial manufacturing is to provide non-CAD users with an easy to use, interactive 3D view of their products - in some cases it's directly used by people on the shop floor, but in cases where paper is really ingrained in the process, AutoVue can be used by a technical publications person to create illustrative 2D views that can be printed that show all of the details necessary to complete the work. Are you making the move to model based design? Is AutoVue helping you with your challenges? Let us know in the comments below.

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  • Sample domain model for online store

    - by Carel
    We are a group of 4 software development students currently studying at the Cape Peninsula University of Technology. Currently, we are tasked with developing a web application that functions as a online store. We decided to do the back-end in Java while making use of Google Guice for persistence(which is mostly irrelevant for my question). The general idea so far to use PHP to create the website. We decided that we would like to try, after handing in the project, and register a business to actually implement the website. The problem we have been experiencing is with the domain model. These are mostly small issues, however they are starting to impact the schedule of our project. Since we are all young IT students, we have virtually no experience in the business world. As such, we spend quite a significant amount of time planning the domain model in the first place. Now, some of the issues we're picking up is say the reference between the Customer entity and the order entity. Currently, we don't have the customer id in the order entity and we have a list of order entities in the customer entity. Lately, I have wondered if the persistence mechanism will put the client id physically in the order table, even if it's not in the entity? So, I started wondering, if you load a customer object, it will search the entire order table for orders with the customer's id. Now, say you have 10 000 customers and 500 000 orders, won't this take an extremely long time? There are also some business processes that I'm not completely clear on. Finally, my question is: does anyone know of a sample domain model out there that is similar to what we're trying to achieve that will be safe to look at as a reference? I don't want to be accused of stealing anybody's intellectual property, especially since we might implement this as a business.

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  • Logical and Physical Modeling for Analytical Applications

    - by Dejan Sarka
    I am proud to announce that my first course for Pluralsight is released. The course title is Logical and Physical Modeling for Analytical Applications. Here is the description of the course. A bad data model leads to an application that does not perform well. Therefore, when developing an application, you should create a good data model from the start. However, even the best logical model can’t help when the physical implementation is bad. It is also important to know how SQL Server stores and accesses data, and how to optimize the data access. Database optimization starts by splitting transactional and analytical applications. In this course, you learn how to support analytical applications with logical design, get understanding of the problems with data access for queries that deal with large amounts of data, and learn about SQL Server optimizations that help solving these problems. Enjoy the course!

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  • Polymorphic associations in CakePHP2

    - by Joseph
    I have 3 models, Page , Course and Content Page and Course contain meta data and Content contains HTML content. Page and Course both hasMany Content Content belongsTo Page and Course To avoid having page_id and course_id fields in Content (because I want this to scale to more than just 2 models) I am looking at using Polymorphic Associations. I started by using the Polymorphic Behavior in the Bakery but it is generating waaay too many SQL queries for my liking and it's also throwing an "Illegal Offset" error which I don't know how to fix (it was written in 2008 and nobody seems to have referred to it recently so perhaps the error is due to it not having been designed for Cake 2?) Anyway, I've found that I can almost do everything I need by hardcoding the associations in the models as such: Page Model CREATE TABLE `pages` ( `id` int(11) NOT NULL AUTO_INCREMENT, `title` varchar(255) COLLATE utf8_unicode_ci NOT NULL, `slug` varchar(255) COLLATE utf8_unicode_ci NOT NULL, `created` datetime NOT NULL, `updated` datetime NOT NULL, PRIMARY KEY (`id`) ) <?php class Page extends AppModel { var $name = 'Page'; var $hasMany = array( 'Content' => array( 'className' => 'Content', 'foreignKey' => 'foreign_id', 'conditions' => array('Content.class' => 'Page'), ) ); } ?> Course Model CREATE TABLE `courses` ( `id` int(11) NOT NULL AUTO_INCREMENT, `title` varchar(255) COLLATE utf8_unicode_ci NOT NULL, `slug` varchar(255) COLLATE utf8_unicode_ci NOT NULL, `created` datetime NOT NULL, `updated` datetime NOT NULL, PRIMARY KEY (`id`) ) <?php class Course extends AppModel { var $name = 'Course'; var $hasMany = array( 'Content' => array( 'className' => 'Content', 'foreignKey' => 'foreign_id', 'conditions' => array('Content.class' => 'Course'), ) ); } ?> Content model CREATE TABLE IF NOT EXISTS `contents` ( `id` int(11) unsigned NOT NULL AUTO_INCREMENT, `class` varchar(30) COLLATE utf8_unicode_ci NOT NULL, `foreign_id` int(11) unsigned NOT NULL, `title` varchar(100) COLLATE utf8_unicode_ci NOT NULL, `content` text COLLATE utf8_unicode_ci NOT NULL, `created` datetime DEFAULT NULL, `modified` datetime DEFAULT NULL, PRIMARY KEY (`id`) ) <?php class Content extends AppModel { var $name = 'Content'; var $belongsTo = array( 'Page' => array( 'foreignKey' => 'foreign_id', 'conditions' => array('Content.class' => 'Page') ), 'Course' => array( 'foreignKey' => 'foreign_id', 'conditions' => array('Content.class' => 'Course') ) ); } ?> The good thing is that $this->Content->find('first') only generates a single SQL query instead of 3 (as was the case with the Polymorphic Behavior) but the problem is that the dataset returned includes both of the belongsTo models, whereas it should only really return the one that exists. Here's how the returned data looks: array( 'Content' => array( 'id' => '1', 'class' => 'Course', 'foreign_id' => '1', 'title' => 'something about this course', 'content' => 'The content here', 'created' => null, 'modified' => null ), 'Page' => array( 'id' => null, 'title' => null, 'slug' => null, 'created' => null, 'updated' => null ), 'Course' => array( 'id' => '1', 'title' => 'Course name', 'slug' => 'name-of-the-course', 'created' => '2012-10-11 00:00:00', 'updated' => '2012-10-11 00:00:00' ) ) I only want it to return one of either Page or Course depending on which one is specified in Content.class UPDATE: Combining the Page and Course models would seem like the obvious solution to this problem but the schemas I have shown above are just shown for the purpose of this question. The actual schemas are actually very different in terms of their fields and the each have a different number of associations with other models too. UPDATE 2 Here is the query that results from running $this->Content->find('first'); : SELECT `Content`.`id`, `Content`.`class`, `Content`.`foreign_id`, `Content`.`title`, `Content`.`slug`, `Content`.`content`, `Content`.`created`, `Content`.`modified`, `Page`.`id`, `Page`.`title`, `Page`.`slug`, `Page`.`created`, `Page`.`updated`, `Course`.`id`, `Course`.`title`, `Course`.`slug`, `Course`.`created`, `Course`.`updated` FROM `cakedb`.`contents` AS `Content` LEFT JOIN `cakedb`.`pages` AS `Page` ON (`Content`.`foreign_id` = `Page`.`id` AND `Content`.`class` = 'Page') LEFT JOIN `cakedb`.`courses` AS `Course` ON (`Content`.`foreign_id` = `Course`.`id` AND `Content`.`class` = 'Course') WHERE 1 = 1 LIMIT 1

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  • General rule - when to use a model (Codeigniter)

    - by pingu
    Hi guys, I was just curious as to what the rule of thumb was for models. Generally, I use them only for situations where I need to add/edit or update database entries for an object. However, I'm building an app at the moment that has a "config" table which holds various data, such as last updated, which will control when certain features in the app should be displayed. In this instance, I will mostly need to retrieve data from the config table. Is it worth putting these config methods in model? I'm interested to hear how more experienced coders approach the MVC methodology in CI - example pseudo methods (e.g., what methods relating to the same object you'd use in the model and the controller) would be most helpful.

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  • Cakephp change model's title without rename model/dbtable

    - by Vincent
    I have a table that store all information about class, but because Class is reserved for class name I had to rename the table from classes to types. But in the view section I need it to be displayed as "Class", including the Paginator links. Anyway to achieve this by adding something in the Type model, without completely customize Paginator and and all view compoenents?

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  • Oracle Communications Data Model

    - by jean-pierre.dijcks
    I've mentioned OCDM in previous posts but found the following (see end of the post) podcast on the topic and figured it is worthwhile to spread the news some more. ORetailDM and OCommunicationsDM are the two data models currently available from Oracle. Both are intended to capture: Business best practices and industry knowledge Pre-built advanced analytics intended to predict future events before they happen (like the Churn model shown below) Oracle technology best practices to ensure optimal performance of the model All of this typically comes with a reduced time to implementation, or as the marketing slogan goes, reduced time to value. Here are the links: Podcast on OCDM OTN pages for OCDM and ORDM

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  • Architecting multi-model multi-DB ASP.NET MVC solution

    - by A. Murray
    I have an ASP.NET MVC 4 solution that I'm putting together, leveraging IoC and the repository pattern using Entity Framework 5. I have a new requirement to be able to pull data from a second database (from another internal application) which I don't have control over. There is no API available unfortunately for the second application and the general pattern at my place of work is to go direct to the database. I want to maintain a consistent approach to modeling the domain and use entity framework to pull the data out, so thus far I have used Entity Framework's database first approach to generate a domain model and database context over the top of this. However, I've become a little stuck on how to include the second domain model in the application. I have a generic repository which I've now moved out to a common DataAccess project, but short of creating two distinct wrappers for the generic repository (so each can identify with a specific database context), I'm struggling to see how I can elegantly include multiple models?

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  • Trying to Nullify Django model fields with method where model and fields are parameters

    - by Johnny4000
    I'm trying to write a method like the below where a list of fields (a subset of all the fields) is passed in as a parameter and has their column values set to null. I would be happy of I could get a method with just the fields as a parameter like below, but having the model as a parameter would be even better. from my_project.my_app.models import MyModel def nullify_columns (self, null_fields): field_names = MyModel._meta.get_all_field_names() for field in field_names: if field in null_fields: # The below line does not work because I'm not sure how to # dynamically assign the field name. MyModel.objects.all().update( (MyModel.get_field(field).column) = None) Right now I have something like if 'column1' in list_of_fields: MyModel.objects.all().update(column1 = None) if 'column2' in list_of_fields: MyModel.objects.all().update(column2 = None) etc. which is horrible, but works.

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  • How do I setup model associations in an RSpec test?

    - by Eric M.
    I've pastied the specs I've written for the posts/show.html.erb view in an application I'm writing as a means to learn RSpec. I am still learning about mocks and stubbing. This question is specific to the "should list all related comments" spec. What I want is to test that the show view displays a post's comments. But what I'm not sure about is how to setup this test and then have the test iterate through with should contain('xyz') statements. Any hints? Other suggestions are also appreciated! Thanks. ---Edit Some more information. I have a named_scope applied to comments in my view (I know, I did this a bit backwards in this case), so @post.comments.approved_is(true). The code pastied responds with the error "undefined method `approved_is' for #", which makes sense since I told it stub comments and return a comment. I'm still not sure, however, how to chain the stubs so that @post.comments.approved_is(true) will return an array of comments.

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  • Rails Associations Question

    - by Mutuelinvestor
    I'm new to rails and have volunteered to help out the local High School Track team with a simple database that tracks the runners performances. For the moment, I have three models: Runners, Race_Data and Races. I have the following associations. Runners have_many Race_Data Races have_many Race_Data I also want create the association Runners Have_Many Races Through Race_Data, but as my look at the diagram I have drawn, there is already a many to one relationship from Race_data to Races. Does the combination of Runners having many Race_Data and Race_Data having one Race imply a Many_to_Many relationship between Runners and Races?

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  • ActiveRecord Associations Question

    - by Mutuelinvestor
    I'm new to rails and have volunteered to help out the local High School Track team with a simple database that tracks the runners performances. For the moment, I have three models: Runners, Race_Data and Races. I have the following associations. Runners have_many Race_Data Races have_many Race_Data I also want create the association Runners Have_Many Races Through Race_Data, but as my look at the diagram I have drawn, there is already a many to one relationship from Race_data to Races. Does the combination of Runners having many Race_Data and Race_Data having one Race imply a Many_to_Many relationship between Runners and Races?

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  • rails Creating a model instance automatically when another is created

    - by bob
    Hello I have a user model and a ratings model. Whenever a new user is created I want to create a new feedback model with it automatically. Each user model has one feedback model and each feedback model has many ratings. My Classes class User < ActiveRecord::Base end class Feedback < ActiveRecord::Base belongs_to :user has_many :ratings end class Rating < ActiveRecord::Base belongs_to :feedback end My database tables -user doesn't have anything special -feedback has user_id. This user_id should be the same as the user that has just been created. For example, user_id of 1 is created, then a feedback model should be created that belongs to user_id of 1. So the user_id column in the feedback database will also be 1. - Rating has a feedback_id and a user_id the user_id in this case is the id of the person who submitted the rating. I am having it assigned through the build command. I believe my process is correct here. The Goal The goal is to have each user have a feedback table that has many ratings from other users. So if someone goes to the feedback page, they will see all the ratings given and by who. Is there a better way to approach this? How do you create a model of feedback with the same id as the user being created right when a new user is created. The idea is that when a user is created a feedback is created associated with that user so people can then go to http://localhost:3000/users/1/feedback/ and submit new ratings. I'm trying to bypass having a user rate another user with just a ratings model because I'm not sure how to do it.

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  • How to avoid multiple, unused has_many associations when using multiple models for the same entity (

    - by mikep
    Hello, I'm looking for a nice, Ruby/Rails-esque solution for something. I'm trying to split up some data using multiple tables, rather than just using one gigantic table. My reasoning is pretty much to try and avoid the performance drop that would come with having a big table. So, rather than have one table called books, I have multiple tables: books1, books2, books3, etc. (I know that I could use a partition, but, for now, I've decided to go the 'multiple tables' route.) Each user has their books placed into a specific table. The actual book table is chosen when the user is created, and all of their books go into the same table. The goal is to try and keep each table pretty much even -- but that's a different issue. One thing I don't particularly want to have is a bunch of unused associations in the User class. Right now, it looks like I'd have to do the following: class User < ActiveRecord::Base has_many :books1, :books2, :books3, :books4, :books5 end class Books1 < ActiveRecord::Base belongs_to :user end class Books2 < ActiveRecord::Base belongs_to :user end First off, for each specific user, only one of the book tables would be usable/applicable, since all of a user's books are stored in the same table. So, only one of the associations would be in use at any time and any other has_many :bookX association that was loaded would be a waste. I don't really know Ruby/Rails does internally with all of those has_many associations though, so maybe it's not so bad. But right now I'm thinking that it's really wasteful, and that there may just be a better, more efficient way of doing this. Is there's some sort of special Ruby/Rails methodology that could be applied here to avoid having to have all of those has_many associations? Also, does anyone have any advice on how to abstract the fact that there's multiple book tables behind a single books model/class?

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  • Including associations optimization in Rails

    - by Vitaly
    Hey, I'm looking for help with Ruby optimization regarding loading of associations on demand. This is simplified example. I have 3 models: Post, Comment, User. References are: Post has many comments and Comment has reference to User (:author). Now when I go to the post page, I expect to see post body + all comments (and their respective authors names). This requires following 2 queries: select * from Post -- to get post data (1 row) select * from Comment inner join User -- to get comment + usernames (N rows) In the code I have: Post.find(params[:id], :include => { :comments => [:author] } But it doesn't work as expected: as I see in the back end, there're still N+1 hits (some of them are cached though). How can I optimize that?

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  • Rails Polymorphic Association with multiple associations on the same model

    - by Matt Rogish
    My question is essentially the same as this one: http://stackoverflow.com/questions/1168047/polymorphic-association-with-multiple-associations-on-the-same-model However, the proposed/accepted solution does not work, as illustrated by a commenter later. I have a Photo class that is used all over my app. A post can have a single photo. However, I want to re-use the polymorphic relationship to add a secondary photo. Before: class Photo belongs_to :attachable, :polymorphic => true end class Post has_one :photo, :as => :attachable, :dependent => :destroy end Desired: class Photo belongs_to :attachable, :polymorphic => true end class Post has_one :photo, :as => :attachable, :dependent => :destroy has_one :secondary_photo, :as => :attachable, :dependent => :destroy end However, this fails as it cannot find the class "SecondaryPhoto". Based on what I could tell from that other thread, I'd want to do: has_one :secondary_photo, :as => :attachable, :class_name => "Photo", :dependent => :destroy Except calling Post#secondary_photo simply returns the same photo that is attached via the Photo association, e.g. Post#photo === Post#secondary_photo. Looking at the SQL, it does WHERE type = "Photo" instead of, say, "SecondaryPhoto" as I'd like... Thoughts? Thanks!

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  • Passing two variables to separate table...associations problem

    - by bgadoci
    I have developed an application and I seem to be having some problems with my associations. I have the following: class User < ActiveRecord::Base acts_as_authentic has_many :questions, :dependent => :destroy has_many :sites , :dependent => :destroy end Questions class Question < ActiveRecord::Base has_many :sites, :dependent => :destroy has_many :notes, :through => :sites belongs_to :user end Sites (think of this as answers to questions) class Site < ActiveRecord::Base acts_as_voteable :vote_counter => true belongs_to :question belongs_to :user has_many :notes, :dependent => :destroy has_many :likes, :dependent => :destroy has_attached_file :photo, :styles => { :small => "250x250>" } validates_presence_of :name, :description end When a Site (answer) is created I am successfully passing the question_id to the Sites table but I can't figure out how to also pass the user_id. Here is my SitesController#create def create @question = Question.find(params[:question_id]) @site = @question.sites.create!(params[:site]) respond_to do |format| format.html { redirect_to(@question) } format.js end end

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  • Ruby on Rails ActiveRecord/Include/Associations can't get my query to work

    - by Cypher
    I just started learning Rails and I'm just trying to set up query via associations. All the queries I try to write seem to be doing bizzare things and end up trying to query two tables parsed together with an '_' as one table. I have no clue why this would ever happen My tables are as follows: schools: id name variables: id name type var_entries: id variable_id entry school_entries: id school_id var_entry_id my rails association tables are $local = { :adapter => "mysql", :host => "localhost", :port => "3306".to_i, :database => "spy_2", :username =>"root", :password => "vertrigo" } class School < ActiveRecord::Base establish_connection $local has_many :school_entries has_many :var_entries, :through => school_entries end class Variable < ActiveRecord::Base establish_connection $local has_many :var_entries has_many :school_entries, :through => :var_entries end class VarEntry < ActiveRecord::Base establish_connection $local has_many_and_belongs_to :school_entries belongs_to :variables end class SchoolEntry < ActiveRecord::Base establish_connection $local belongs_to :school has_many :var_entries end I want to do this sql query: SELECT school_id, variable_id,rank FROM school_entries, variables, var_entries, schools WHERE var_entries.variable_id = variables.id AND school_entries.var_entry_id = var_entries.id AND schools.id = school_entries.school_id AND variables.type = 'number'; and put it into Rails notation: here is one of my many failed attempts schools = VarEntry.all(:include => [:school_entries, :variables], :conditions => "variables.type = 'number'") the error: 'const_missing': uninitialized constant VarEntry::Variables (NameError) if i remove variables schools = VarEntry.all(:include => [:school_entries, :variables], :conditions => "type = 'number'") the error is: Mysql::Error: Unkown column 'type' in 'where clause': SELECT * FROM 'var_entries' WHERE (type=number) (ActiveRecord::StatementInvalid) Can anyone tell me where I'm going horribly wrong?

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  • Rails preventing duplicates in polymorphic has_many :through associations

    - by seaneshbaugh
    Is there an easy or at least elegant way to prevent duplicate entries in polymorphic has_many through associations? I've got two models, stories and links that can be tagged. I'm making a conscious decision to not use a plugin here. I want to actually understand everything that's going on and not be dependent on someone else's code that I don't fully grasp. To see what my question is getting at, if I run the following in the console (assuming the story and tag objects exist in the database already) s = Story.find_by_id(1) t = Tag.find_by_id(1) s.tags << t s.tags << t My taggings join table will have two entries added to it, each with the same exact data (tag_id = 1, taggable_id = 1, taggable_type = "Story"). That just doesn't seem very proper to me. So in an attempt to prevent this from happening I added the following to my Tagging model: before_validation :validate_uniqueness def validate_uniqueness taggings = Tagging.find(:all, :conditions => { :tag_id => self.tag_id, :taggable_id => self.taggable_id, :taggable_type => self.taggable_type }) if !taggings.empty? return false end return true end And it works almost as intended, but if I attempt to add a duplicate tag to a story or link I get an ActiveRecord::RecordInvalid: Validation failed exception. It seems that when you add an association to a list it calls the save! (rather than save sans !) method which raises exceptions if something goes wrong rather than just returning false. That isn't quite what I want to happen. I suppose I can surround any attempts to add new tags with a try/catch but that goes against the idea that you shouldn't expect your exceptions and this is something I fully expect to happen. Is there a better way of doing this that won't raise exceptions when all I want to do is just silently not save the object to the database because a duplicate exists?

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