1366 0 true 2008-09-08T20:58:30+01:00 7211 11 guide-to-active-record-associations 19707 16213 published activerecord 2009-12-15T17:30:57+00:00 35500 Todd Mike Gunderloy Pratik http://rails.lighthouseapp.com/projects/16213/tickets/11 1366 0 false 2008-09-08T20:58:30+01:00 7211 --- {} 11 guide-to-active-record-associations 0 16213 new activerecord associations 2008-09-08T20:58:37+01:00 7211 Mike Gunderloy Mike Gunderloy Pratik http://rails.lighthouseapp.com/projects/16213/tickets/11 1366 0 I've checked in a first cut at this one - doc/guides/activerecord/association_basics.txt. I need to clean up some of the AsciiDoc formatting, but it's to the point where comments are welcome. <div><p>I've checked in a first cut at this one - doc/guides/activerecord/association_basics.txt. I need to clean up some of the AsciiDoc formatting, but it's to the point where comments are welcome.</p></div> false 2008-09-08T20:59:21+01:00 7211 --- {} 11 guide-to-active-record-associations 0 16213 new activerecord associations 2008-09-08T20:59:28+01:00 7211 Mike Gunderloy Mike Gunderloy Pratik http://rails.lighthouseapp.com/projects/16213/tickets/11 1366 0 Note : This had already been approved. <div><p>Note : This had already been approved.</p></div> false 2008-09-09T00:45:12+01:00 7211 --- {} 11 guide-to-active-record-associations 0 16213 new activerecord associations 2008-09-09T00:45:17+01:00 1366 Pratik Mike Gunderloy Pratik http://rails.lighthouseapp.com/projects/16213/tickets/11 1366 0 I just added some images and did some miscellaneous cleanup. Unless there's feedback, I think this one is finished. <div><p>I just added some images and did some miscellaneous cleanup. Unless there's feedback, I think this one is finished.</p></div> false 2008-09-22T16:20:04+01:00 7211 --- :tag: activerecord associations 11 guide-to-active-record-associations 0 16213 new activerecord associations 2008-09-22T16:20:05+01:00 7211 Mike Gunderloy Mike Gunderloy Pratik http://rails.lighthouseapp.com/projects/16213/tickets/11 1366 0 First of all, once again great guide. But since there's no feedback yet, I'll just dump here my rough notes since I probably won't have time to sort it our for a few days. Mostly nitpicking, though. If there's something not clear enough, let me know and I'll try to clarify. Without further ado, here it is: - model names are plural instead of singular at the beginning - has_many :through is missing an "end" at the bottom of both code segments and Patient model picture has indentation bug - code blocks needlessly repeated after the ER diagrams - couldn't understand polymorphic associations. Where are :imageable and ":as => :attachable" on both models coming from. Isn't :as supposed to be different for those two models? What does Rails make out of :imageable and :attachable? - clarify weather belongs_to :order :include => :order is needed in order to eager load the associated Order model or that one is eager loaded by default - fonts for < h5 >< tt > should be made 20% bigger - in 4.2.1 in "Each instance of the order model will have these methods:" "order" should be replace with "supplier" - in 4.2.1 in build and create_association sections there is "and the link through this its foreign key will be set" - in 4.3.1 each line in second code block is wrapped in + signs - in 4.3.1 and 4.4.1 in collection<< there is "_collection<<" where _ is probably not supposed to be there - in 4.3.1 should ":dependent ⇒ :delete_all" be ":dependent ⇒ :delete" instead? :delete_all is not mentioned in :dependent section - in 4.3.1 in collection.create there is "one a new" where "a" needs to be removed - in 4.3.2 there is "This section cover " where "cover" => "covers" - in 4.3.2 :order there is "(in the syntax used by a SQL WHERE clause)". "WHERE" => "ORDER BY" - in 4.3.2 :include in both code blocks "belongs_to :orders". Model should be singular I guess. - in 4.4.1 after the list of 13 methods there is "_collection_singular" where leading _ probably shouldn't be there - in 4.4.1 in first code block there is "class Parts" when it should probably be "class Part" - in 4.4.1 second code block has excess plus signs - in 4.4.1 collection.delete: "join table+" - in 4.4.1 collection.clear: does it set associated model's foreign key to NULL? I only had time to read up to section 4.4.2 so polymorphic associations my be explained better later in the guide. <div><p>First of all, once again great guide. But since there's no feedback yet, I'll just dump here my rough notes since I probably won't have time to sort it our for a few days. Mostly nitpicking, though. If there's something not clear enough, let me know and I'll try to clarify. Without further ado, here it is:</p> <ul> <li>model names are plural instead of singular at the beginning</li> <li>has_many :through is missing an "end" at the bottom of both code segments and Patient model picture has indentation bug</li> <li>code blocks needlessly repeated after the ER diagrams</li> <li>couldn't understand polymorphic associations. Where are :imageable and ":as =&gt; :attachable" on both models coming from. Isn't :as supposed to be different for those two models? What does Rails make out of :imageable and :attachable?</li> <li>clarify weather belongs_to :order :include =&gt; :order is needed in order to eager load the associated Order model or that one is eager loaded by default</li> <li>fonts for &lt; h5 &gt;&lt; tt &gt; should be made 20% bigger</li> <li>in 4.2.1 in "Each instance of the order model will have these methods:" "order" should be replace with "supplier"</li> <li>in 4.2.1 in build and create_association sections there is "and the link through this its foreign key will be set"</li> <li>in 4.3.1 each line in second code block is wrapped in + signs</li> <li>in 4.3.1 and 4.4.1 in collection&lt;&lt; there is "_collection&lt;&lt;" where _ is probably not supposed to be there</li> <li>in 4.3.1 should ":dependent &#8658; :delete_all" be ":dependent &#8658; :delete" instead? :delete_all is not mentioned in :dependent section</li> <li>in 4.3.1 in collection.create there is "one a new" where "a" needs to be removed</li> <li>in 4.3.2 there is "This section cover " where "cover" =&gt; "covers"</li> <li>in 4.3.2 :order there is "(in the syntax used by a SQL WHERE clause)". "WHERE" =&gt; "ORDER BY"</li> <li>in 4.3.2 :include in both code blocks "belongs_to :orders". Model should be singular I guess.</li> <li>in 4.4.1 after the list of 13 methods there is "_collection_singular" where leading _ probably shouldn't be there</li> <li>in 4.4.1 in first code block there is "class Parts" when it should probably be "class Part"</li> <li>in 4.4.1 second code block has excess plus signs</li> <li>in 4.4.1 collection.delete: "join table+"</li> <li>in 4.4.1 collection.clear: does it set associated model's foreign key to NULL?</li> </ul> <p>I only had time to read up to section 4.4.2 so polymorphic associations my be explained better later in the guide.</p></div> false 2008-09-24T22:11:14+01:00 7211 --- {} 11 guide-to-active-record-associations 0 16213 new activerecord associations 2008-09-24T22:11:15+01:00 718 Nemanja Mike Gunderloy Pratik http://rails.lighthouseapp.com/projects/16213/tickets/11 1366 0 Excellent feedback! Thanks. It helps *immensely* to have someone else doing a tech edit. I'll start tidying these things up. <div><p>Excellent feedback! Thanks. It helps <em>immensely</em> to have someone else doing a tech edit.</p> <p>I'll start tidying these things up.</p></div> false 2008-09-24T22:17:52+01:00 7211 --- {} 11 guide-to-active-record-associations 0 16213 new activerecord associations 2008-09-24T22:17:56+01:00 7211 Mike Gunderloy Mike Gunderloy Pratik http://rails.lighthouseapp.com/projects/16213/tickets/11 1366 0 I've made most of these changes. Exceptions: * I'm leaving the code snippets in the ER diagrams, even though they're redundant with the text, because I want the diagrams to be reusable separately. * Changing fonts in the stylesheet should be left to the overall designer. <div><p>I've made most of these changes. Exceptions:</p> <ul> <li>I'm leaving the code snippets in the ER diagrams, even though they're redundant with the text, because I want the diagrams to be reusable separately.</li> <li>Changing fonts in the stylesheet should be left to the overall designer.</li> </ul></div> false 2008-09-26T10:36:34+01:00 7211 --- {} 11 guide-to-active-record-associations 0 16213 new activerecord associations 2008-09-26T10:36:36+01:00 7211 Mike Gunderloy Mike Gunderloy Pratik http://rails.lighthouseapp.com/projects/16213/tickets/11 1366 0 true 2008-09-30T00:08:36+01:00 7211 --- :state: new 11 guide-to-active-record-associations 0 16213 resolved activerecord associations 2008-09-30T00:08:37+01:00 1366 Pratik Mike Gunderloy Pratik http://rails.lighthouseapp.com/projects/16213/tickets/11 1366 0 I'm new to rails, but is this a possible error?: The syntax recommended through out the guide for the :class_name option makes use of a symbol to refer to actual class name: @@@ belongs_to :customer, :class_name => :user @@@ Using this syntax caused me to get "can't convert Symbol into String" errors. The following definition worked though! @@@ belongs_to :customer, :class_name => "User" @@@ <div><p>I'm new to rails, but is this a possible error?:</p> <p>The syntax recommended through out the guide for the :class_name option makes use of a symbol to refer to actual class name:</p> <pre><code> belongs_to :customer, :class_name =&gt; :user </code></pre> <p>Using this syntax caused me to get "can't convert Symbol into String" errors.</p> <p>The following definition worked though!</p> <pre><code> belongs_to :customer, :class_name =&gt; &quot;User&quot; </code></pre></div> true 2008-10-09T19:22:41+01:00 7211 --- {} 11 guide-to-active-record-associations 0 16213 resolved activerecord associations 2008-10-09T19:22:46+01:00 33930 LK Mike Gunderloy Pratik http://rails.lighthouseapp.com/projects/16213/tickets/11 1366 0 You are absolutely right, and I am absolutely embarrassed. Thanks for pointing that out! <div><p>You are absolutely right, and I am absolutely embarrassed. Thanks for pointing that out!</p></div> true 2008-10-11T23:56:05+01:00 7211 --- {} 11 guide-to-active-record-associations 0 16213 resolved activerecord associations 2008-10-11T23:56:09+01:00 7211 Mike Gunderloy Mike Gunderloy Pratik http://rails.lighthouseapp.com/projects/16213/tickets/11 1366 0 In 2.10 (Self Joins), the last line should be: `@employee.manager` instead of `@employee.managers` (because `belongs_to` is a one-to-one association) <div><p>In 2.10 (Self Joins), the last line should be: <code>@employee.manager</code> instead of <code>@employee.managers</code></p> <p>(because <code>belongs_to</code> is a one-to-one association)</p></div> true 2008-10-28T10:12:16+00:00 7211 --- {} 11 guide-to-active-record-associations 0 16213 resolved activerecord associations 2008-10-28T10:12:19+00:00 10258 Dov Murik Mike Gunderloy Pratik http://rails.lighthouseapp.com/projects/16213/tickets/11 1366 0 Thanks, fixed. Y'all should feel free to send patches for tiny little typoes :) <div><p>Thanks, fixed.</p> <p>Y'all should feel free to send patches for tiny little typoes :)</p></div> true 2008-10-28T11:16:54+00:00 7211 --- {} 11 guide-to-active-record-associations 0 16213 resolved activerecord associations 2008-10-28T11:16:57+00:00 7211 Mike Gunderloy Mike Gunderloy Pratik http://rails.lighthouseapp.com/projects/16213/tickets/11 1366 0 Section 2.10 (Self Joins) is unclear to me. I'm not sure if this is an error or not. Should it read ':class_name => "Employee"'? If it is correct as it stands, then what does the User class look like? What is the relationship between them? class Employee < ActiveRecord::Base has_many :subordinates, :class_name => "User", :foreign_key => "manager_id" belongs_to :manager, :class_name => "User" end Some more explanation seems desireable. <div><p>Section 2.10 (Self Joins) is unclear to me. I'm not sure if this is an error or not. Should it read ':class_name =&gt; "Employee"'? If it is correct as it stands, then what does the User class look like? What is the relationship between them?</p> <p>class Employee &lt; ActiveRecord::Base has_many :subordinates, :class_name =&gt; "User", :foreign_key =&gt; "manager_id" belongs_to :manager, :class_name =&gt; "User" end</p> <p>Some more explanation seems desireable.</p></div> true 2008-11-10T00:54:33+00:00 7211 --- {} 11 guide-to-active-record-associations 0 16213 resolved activerecord associations 2008-11-10T00:54:37+00:00 28039 Brandon Zylstra Mike Gunderloy Pratik http://rails.lighthouseapp.com/projects/16213/tickets/11 1366 0 Another great guide. one error I found when talking about :offset ... "For example, if you set :offset ⇒ 11, it will skip the first 10 records." That is technically true, but to be more precise, the first 11 records are skipped because :offset => 0 skips 0 records, :offset => 1 skips 1 records, etc. <div><p>Another great guide. one error I found when talking about :offset ...</p> <p>"For example, if you set :offset &#8658; 11, it will skip the first 10 records."</p> <p>That is technically true, but to be more precise, the first 11 records are skipped because :offset =&gt; 0 skips 0 records, :offset =&gt; 1 skips 1 records, etc.</p></div> true 2008-11-18T15:28:37+00:00 7211 --- {} 11 guide-to-active-record-associations 0 16213 resolved activerecord associations 2008-11-18T15:28:43+00:00 38006 Anna Lissa Cruz Mike Gunderloy Pratik http://rails.lighthouseapp.com/projects/16213/tickets/11 1366 0 Thanks for the corrections. New draft uploading. <div><p>Thanks for the corrections. New draft uploading.</p></div> true 2008-11-18T16:43:15+00:00 7211 --- {} 11 guide-to-active-record-associations 0 16213 resolved activerecord associations 2008-11-18T16:43:17+00:00 7211 Mike Gunderloy Mike Gunderloy Pratik http://rails.lighthouseapp.com/projects/16213/tickets/11 1366 0 looks like methods confused with parameters: class CreateOrders < ActiveRecord::Migration def self.up create_table :orders do |t| t.order_date :datetime t.order_number :string t.customer_id :integer end end <div><p>looks like methods confused with parameters:</p> <p>class CreateOrders &lt; ActiveRecord::Migration def self.up</p> <pre> <code>create_table :orders do |t| t.order_date :datetime t.order_number :string t.customer_id :integer end </code> </pre> <p>end</p></div> true 2008-11-27T15:28:08+00:00 7211 --- :tag: activerecord associations 11 guide-to-active-record-associations 0 16213 resolved activerecord 2008-11-27T15:28:14+00:00 39101 dmitry zhelnin Mike Gunderloy Pratik http://rails.lighthouseapp.com/projects/16213/tickets/11 1366 0 Ugh, that was stupid, wasn't it? FIxed. <div><p>Ugh, that was stupid, wasn't it? FIxed.</p></div> true 2008-11-30T13:03:05+00:00 7211 --- {} 11 guide-to-active-record-associations 0 16213 resolved activerecord 2008-11-30T13:03:09+00:00 7211 Mike Gunderloy Mike Gunderloy Pratik http://rails.lighthouseapp.com/projects/16213/tickets/11 1366 0 it would be nice if there were some examples for the more complex options, eg finder_sql. there are already a few examples for these things in the normal rails API docs, but they are a bit light on the explanations i was hoping to find here. o/wise, this is a great little guide for the simple stuff. <div><p>it would be nice if there were some examples for the more complex options, eg finder_sql. there are already a few examples for these things in the normal rails API docs, but they are a bit light on the explanations i was hoping to find here. o/wise, this is a great little guide for the simple stuff.</p></div> true 2008-12-02T21:16:51+00:00 7211 --- {} 11 guide-to-active-record-associations 0 16213 resolved activerecord 2008-12-02T21:16:54+00:00 39590 charlesdeb Mike Gunderloy Pratik http://rails.lighthouseapp.com/projects/16213/tickets/11 1366 0 In the first section, "Why Associations?", the last example implies that the customers orders will be destroyed when the customer is. The problem is the orders association has not been declared as dependent. While the dependent option is explain further down, having users assume it is default behavior seems bad. <div><p>In the first section, "Why Associations?", the last example implies that the customers orders will be destroyed when the customer is. The problem is the orders association has not been declared as dependent. While the dependent option is explain further down, having users assume it is default behavior seems bad.</p></div> true 2009-02-04T18:03:42+00:00 7211 --- {} 11 guide-to-active-record-associations 0 16213 resolved activerecord 2009-02-04T18:03:44+00:00 17315 Tristan Dunn Mike Gunderloy Pratik http://rails.lighthouseapp.com/projects/16213/tickets/11 1366 0 In the third code block: @@@ @orders = Order.find_by_customer_id(@customer.id) @@@ is misleading. It should be @@@ find_all_by_customer_id @@@, otherwise the each loop makes no sense. <div><p>In the third code block:</p> <p>@@@ @orders = Order.find_by_customer_id(@customer.id) @@@</p> <p>is misleading. It should be @@@ find_all_by_customer_id @@@, otherwise the each loop makes no sense.</p></div> true 2009-04-11T16:04:35+01:00 7211 --- :state: resolved 11 guide-to-active-record-associations 0 16213 activerecord 2009-04-11T16:04:39+01:00 29693 Kai Krakow Mike Gunderloy Pratik http://rails.lighthouseapp.com/projects/16213/tickets/11 1366 0 true 2009-04-11T16:09:40+01:00 7211 --- :state: 11 guide-to-active-record-associations 0 16213 published activerecord 2009-04-11T16:09:44+01:00 1366 Pratik Mike Gunderloy Pratik http://rails.lighthouseapp.com/projects/16213/tickets/11 0 In the sections 4.3.1 and 4.4.1 is the following code: collection.exist?(…) which I guess it should be collection.exists?(…) instead off. I have tested in 2.2.x and 2.3.x <div><p>In the sections 4.3.1 and 4.4.1 is the following code:</p> <p>collection.exist?(&#8230;)</p> <p>which I guess it should be collection.exists?(&#8230;) instead off. I have tested in 2.2.x and 2.3.x</p></div> true 2009-05-21T11:50:27+01:00 7211 --- :assigned_user: 1366 11 guide-to-active-record-associations 0 16213 published activerecord 2009-05-21T11:50:31+01:00 53443 Peter Zlatnar Mike Gunderloy http://rails.lighthouseapp.com/projects/16213/tickets/11 1366 0 Thanks Peter, fixed in http://github.com/lifo/docrails/commit/402f08f1efe5dbfbf1cdd4db8b7c6c4bc91574a6 <div><p>Thanks Peter, fixed in <a href= "http://github.com/lifo/docrails/commit/402f08f1efe5dbfbf1cdd4db8b7c6c4bc91574a6"> http://github.com/lifo/docrails/commit/402f08f1efe5dbfbf1cdd4db8b7c...</a></p></div> true 2009-05-23T22:57:10+01:00 7211 --- :assigned_user: 11 guide-to-active-record-associations 0 16213 published activerecord 2009-05-23T22:57:13+01:00 11378 Xavier Noria Mike Gunderloy Pratik http://rails.lighthouseapp.com/projects/16213/tickets/11 1366 0 Kai: fixed in http://github.com/lifo/docrails/commit/39ad75bda2e140008024543692e0c7019a5a4632 Thank you! <div><p>Kai: fixed in <a href= "http://github.com/lifo/docrails/commit/39ad75bda2e140008024543692e0c7019a5a4632"> http://github.com/lifo/docrails/commit/39ad75bda2e140008024543692e0...</a></p> <p>Thank you!</p></div> true 2009-05-23T23:06:27+01:00 7211 --- {} 11 guide-to-active-record-associations 0 16213 published activerecord 2009-05-23T23:06:29+01:00 11378 Xavier Noria Mike Gunderloy Pratik http://rails.lighthouseapp.com/projects/16213/tickets/11 1366 0 This is a nice guide but I still am having trouble understanding why associations are used and why some don't appear to work. For example, the following ruby code works but does not work in an actual rails application. It would help me to understand this better is I understood why something like this is not possible. Is there a reason why I need to always use an extra table for a has_many_and_belongs_to relationship? When I try this in Rails, its willing to do a part of this (e.g, e.department) but not the last '.customers' part? I could of course just to x = e.department and then do x.customers (which does work in Rails) but why do I need to do this in two steps instead of one? I can see that for large datasets why the additional table would help but if the dataset is small why do you need the extra table/steps? SAMPLE CODE require 'rubygems';require 'active_record'; require 'mysql'; ActiveRecord::Base.establish_connection(:adapter => 'mysql', :database => "idea", :username => "myname", :password => 'mypswd') class Employee < ActiveRecord::Base belongs_to :department end class Department < ActiveRecord::Base has_many :departments has_many :comments end class Customers < ActiveRecord::Base belongs_to :department end e = Employee.find(1) #to find the number of customers associated with a particular employee within a department p e.department.customers.size <div><p>This is a nice guide but I still am having trouble understanding why associations are used<br> and why some don't appear to work. For example, the following ruby code works but does not work in an actual rails application. It would help me to understand this better is I understood why something like this is not possible. Is there a reason why I need to always use an extra table for a has_many_and_belongs_to relationship? When I try this in Rails, its willing to do a part of this (e.g, e.department) but not the last '.customers' part? I could of course just to x = e.department and then do x.customers (which does<br> work in Rails) but why do I need to do this in two steps instead of one? I can see that for large datasets why the additional table would help but if the dataset is small why do you need the extra table/steps?</p> <p>SAMPLE CODE<br> require 'rubygems';require 'active_record'; require 'mysql'; ActiveRecord::Base.establish_connection(:adapter =&gt; 'mysql', :database =&gt; "idea", :username =&gt; "myname", :password =&gt; 'mypswd')</p> <p>class Employee &lt; ActiveRecord::Base<br></p> <pre> <code> belongs_to :department</code> </pre> <p>end<br> class Department &lt; ActiveRecord::Base<br></p> <pre> <code> has_many :departments has_many :comments</code> </pre> <p>end<br> class Customers &lt; ActiveRecord::Base<br></p> <pre> <code> belongs_to :department</code> </pre> <p>end<br> e = Employee.find(1)<br></p> <h1>to find the number of customers associated with a particular employee</h1> <p>within a department<br> p e.department.customers.size</p></div> true 2009-12-15T00:24:44+00:00 7211 --- {} 11 guide-to-active-record-associations 0 16213 published activerecord 2009-12-15T00:24:47+00:00 35500 Todd Mike Gunderloy Pratik http://rails.lighthouseapp.com/projects/16213/tickets/11 1366 0 woops, I made a couple of typos. The models should be class Employee < ActiveRecord::Base belongs_to :department end class Department < ActiveRecord::Base has_many :departments has_many :customers end class Customer < ActiveRecord::Base belongs_to :department end <div><p>woops, I made a couple of typos. The models should be</p> <p>class Employee &lt; ActiveRecord::Base<br></p> <pre> <code> belongs_to :department</code> </pre> <p>end<br> class Department &lt; ActiveRecord::Base<br></p> <pre> <code> has_many :departments has_many :customers</code> </pre> <p>end<br> class Customer &lt; ActiveRecord::Base<br></p> <pre> <code> belongs_to :department</code> </pre> <p>end</p></div> true 2009-12-15T06:46:03+00:00 7211 --- {} 11 guide-to-active-record-associations 0 16213 published activerecord 2009-12-15T06:46:06+00:00 35500 Todd Mike Gunderloy Pratik http://rails.lighthouseapp.com/projects/16213/tickets/11 1366 0 I figured out why is doesn't work and to my great shame, I'd actually read this article http://blog.hasmanythrough.com/2008/2/27/count-length-size In rails, you need to use .count and not .size for this to work because the first collection has already been loaded and therefore you are asking for the length and not the count! The length == 0 and so no records are returned. <div><p>I figured out why is doesn't work and to my great shame, I'd actually<br> read this article <a href= "http://blog.hasmanythrough.com/2008/2/27/count-length-size">http://blog.hasmanythrough.com/2008/2/27/count-length-size</a></p> <p>In rails, you need to use .count and not .size for this to work<br> because the first collection has already been loaded and therefore you<br> are asking for the length and not the count! The length == 0 and so<br> no records are returned.</p></div> true 2009-12-15T17:30:54+00:00 7211 --- {} 11 guide-to-active-record-associations 0 16213 published activerecord 2009-12-15T17:30:57+00:00 35500 Todd Mike Gunderloy Pratik http://rails.lighthouseapp.com/projects/16213/tickets/11