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  • Rails 3 find all associated records has_many :through

    - by Sergey
    I would like to list all posts that are connected with some specific category. I have: class Post < ActiveRecord::Base has_many :category_posts has_many :categories, :through => :category_posts end class Category < ActiveRecord::Base has_many :category_posts has_many :posts, :through => :category_posts end class CategoryPost < ActiveRecord::Base belongs_to :category belongs_to :post end And I wanna do something like this Post.where(["category.id = ?", params[:category_id]]) It indeed is very simple task, but I don't know what I should be looking for (keywords). It's the same problem like this, but in rails.

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  • Django design question: extending User to make users that can't log in

    - by jobrahms
    The site I'm working on involves teachers creating student objects. The teacher can choose to make it possible for a student to log into the site (to check calendars, etc) OR the teacher can choose to use the student object only for record keeping and not allow the student to log in. In the student creation form, if the teacher supplies a username and a password, it should create an object of the first kind - one that can log in, i.e. a regular User object. If the teacher does not supply a username/password, it should create the second type. The other requirement is that the teacher should be able to go in later and change a non-logging-in student to the other kind. What's the best way to design for this scenario? Subclass User and make username and password not required? What else would this affect?

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  • Cakephp, an elegant solution to quantities?

    - by Smickie
    Hi, I have a shopping cart system in Cakephp, this table has all your usual maguffins: user_ids, product_ids, option_lists ect. It also has quantity. I currently have some awful nested loops to check if the record is the same as any in there, if so add one to the quantity. If not add a new cart item. This loop has to check associated list items and product options, so it goes quite deep. What I'm wondering is if there is a more elegant way of checking to see if two cart items in a database are similar (everything except for quantity). Cheers!

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  • How to display a tree of objects in a JTree?

    - by paul
    Imagine a collection of objects such as World, Country, Region and City. World contains a list of Country objects, Country contains a list of Region objects etc. I would like to represent this structure in a JTree and be able to add, remove and move objects around the tree. Can I easily create a TableModel from this structure? World would be the root object and I would need to perform some object-specific rendering. Any one know of an appropriate tutorial?

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  • DB Architecture : Linking to intersection or to main tables?

    - by Jean-Nicolas
    Hi, I'm creating fantasy football system on my website but i'm very confuse about how I should link some of my table. Tables The main table is Pool which have all the info about the ruling of the fantasy draft. A standard table User, which contains the usual stuff. Intersection table called pools_users which contains id,pool_id,user_id because a user could be in more than one pool, and a pool contains more than 1 user. The problem Table Selections = that's the table that is causing problem. That's the selection that the user choose for his pool. This is related to the Player table but thats not relevant for this problem. Should I link this table to the table Pools_users or should I link it with both main table Pool and User. This table contains id,pool_id,user_id,player_id,... What is the best way link my tables? When I want to retrieve my data, I normally want the information to be divided BY users. "This user have those selections, this one those selections, etc).

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  • How To Collapse Just One Field in Django Admin?

    - by Apreche
    The django admin allows you to specify fieldsets. You properly structure a tuple that groups different fields together. You can also specify classes for certain groups of fields. One of those classes is collapse, which will hide the field under a collapsable area. This is good for hiding rarely used or advanced fields to keep the UI clean. However, I have a situation where I want to hide just one lonesome field on many different apps. This will be a lot of typing to create a full fieldset specification in every admin.py file just to put one field into the collapsed area. It also creates a difficult maintenance situation because I will have to edit the fieldset every time I edit the associated model. I can easily exclude the field entirely using the exclude option. I want something similar for collapse. Is this possible?

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  • Ruby on Rails : How can i display data for the current view from a different table

    - by krishkule
    This might be a easy-to-answer question, but its a pain in the bum for me.... So... I have two tables - Chords - |id|chord|name|rating|artist_id| Artists - |id|artist| (the relations : chords : belongs_to :artist artists : has_many :chords ) And in the index page for "chords" i want to display chord,name,rating from Chords table AND artist from the Artists table this is the code for the chrod's index.html.erb : <table border="1"> <%@chords.each do |chord|%> <tr> <td><%=chord.artist.artist%></td> <td><%= link_to chord.name, chord %></td> <td><%=chord.rating%></td> <td><%= chord.created_at %></td> </tr> <%end%> </table> The error message is : undefined method `artist' for nil:NilClass Actually, at first it worked, but when i started to create the "new.html.erb" page and the create,new controllers, it stopped working - thats why this is so confusing for me! I will be glad to hear any critique and suggestions! Thank you

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  • How do I implement a DataGrid with an MVVM approach.

    - by Fred
    Hi, I'd like to implement a sort of Addressbook/Contactbook using a Datagrid (or a List) and the MVVM pattern. Something like in Outlook/Thunderbird, where you've a list of your contacts displayed with a 2-3 main fields (name surname for example), and when you double-click a contact, then you get a new modal box that displays all the details of this specific contact. Since a couple of weeks/months, I'm reading a lot of stuff about MVVM pattern on the net, but somehow, I get confused. Until now, I could find any sample like this. (perhaps, I searched wrong?) How could I organize such an application? Thx in advance for your help.

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  • How the swing's BoxModel works ?

    - by sasquatch90
    Let's say I would like to create a simple calculator. It consists of 3 fields. Text field to show result, field with checkboxes to select system and field with numbers. What kind of component should I use for each element ? How can I position elements in my window ? How can I position elements inside component (ie checkboxes) ? This is what I'm trying to achieve. http://img28.imageshack.us/img28/7691/lab8c.jpg

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  • How best to implement support for multiple devices in a web application.

    - by Kabeer
    Hello. My client would like a business application to support 'every possible device'. The application in question is essentially a web application and 'every possible device', I believe encompasses mobile phones, netbooks, ipad, other browser supporting devices, etc. The application is somewhat complex w.r.t. the data it captures and other functions it performs (reporting). If I continue to honor increasing complexity in the application, I guess there are more chances of it not working on other devices. I'd like to know how web applications support multiple devices conventionally? Are there multiple versions of presentation layer (like many times I find m.website.com dedicated for mobile devices)? Further, if my application is to take advantage of Java Script, RIA (Flash, SilverLight) then what are the consequences and workarounds? Mine is a .Net based application and the stack also contains Ext JS Java Script library. While I would like to use it for sure, considering that I would be doing a lot of work in Java Script rather than HTML, this could be a problem. The answer to the above could be descriptive. If there is something already prescribed out there, please share the link(s). Thanks.

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  • How can CopyOnWriteArrayList be thread-safe?

    - by Shooshpanchick
    I've taken a look into OpenJDK's sources of CopyOnWriteArrayList and it seems that all write operations are protected by the same lock and read operations are not protected at all. As I understand, under JMM all accesses to a variable (both read and write) should be protected by lock or reordering effects may occur. For example, set(int, E) method contains these lines (under lock): /* 1 */ int len = elements.length; /* 2 */ Object[] newElements = Arrays.copyOf(elements, len); /* 3 */ newElements[index] = element; /* 4 */ setArray(newElements); The get(int) method, on the other hand, only does return get(getArray(), index);. In my understanding of JMM, this means that get may observe the array in an inconsistent state if statements 1-4 are reordered like 1-2(new)-4-2(copyOf)-3. Do I understand JMM incorrectly or is there any other explanations on why CopyOnWriteArrayList is thread-safe?

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  • C# Interface Method calls from a controller

    - by ArjaaAine
    I was just working on some application architecture and this may sound like a stupid question but please explain to me how the following works: Interface: public interface IMatterDAL { IEnumerable<Matter> GetMattersByCode(string input); IEnumerable<Matter> GetMattersBySearch(string input); } Class: public class MatterDAL : IMatterDAL { private readonly Database _db; public MatterDAL(Database db) { _db = db; LoadAll(); //Private Method } public virtual IEnumerable<Matter> GetMattersBySearch(string input) { //CODE return result; } public virtual IEnumerable<Matter> GetMattersByCode(string input) { //CODE return results; } Controller: public class MatterController : ApiController { private readonly IMatterDAL _publishedData; public MatterController(IMatterDAL publishedData) { _publishedData = publishedData; } [ValidateInput(false)] public JsonResult SearchByCode(string id) { var searchText = id; //better name for this var results = _publishedData.GetMattersBySearch(searchText).Select( matter => new { MatterCode = matter.Code, MatterName = matter.Name, matter.ClientCode, matter.ClientName }); return Json(results); } This works, when I call my controller method from jquery and step into it, the call to the _publishedData method, goes into the class MatterDAL. I want to know how does my controller know to go to the MatterDAL implementation of the Interface IMatterDAL. What if I have another class called MatterDAL2 which is based on the interface. How will my controller know then to call the right method? I am sorry if this is a stupid question, this is baffling me.

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  • What are the names of network interfaces on the Motorola CLIQ XT?

    - by RS
    The network interfaces on Android interfaces are listed as directories in the file system in /sys/class/net/. For most Android devices the network interface for gprs traffic is called rmnet0 and for Wi-Fi it's usually eth0 or tiwlan0. I suspect that the cell interface for the Motorola CLIQ XT is rmnet0, but I would like to have this confirmed + know the name of the Wi-Fi interface. Also it would be good to know the device id for this model. This is the value available as android.os.Build.DEVICE in the Java SDK. (E.g. T-Mobile G1 uses dream, Samsung Galaxy uses GT-I7500, and Motorolda Droid uses sholes.)

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  • ado.net data entity problem

    - by ognjenb
    I have this error Cannot implicitly convert type 'System.Linq.IQueryable' to 'Mvc.Models.engineer'. An explicit conversion exists (are you missing a cast?) after write this code engineer Ing = new engineer(); Ing = from j in testPersons.ibekoengineer select j.Name; What is wrong?

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  • How do I insert data into a object relational table with multiple ref in the schema.

    - by Yiling
    I have a table with a schema of Table(number, ref, ref, varchar2, varchar2,...). How would I insert a row of data into this table? When I do: "insert into table values (1, select ref(p), ref(d), '239 F.3d 1343', '35 USC § 283', ... from plaintiff p, defendant d where p.name='name1' and d.name='name2');" I get a "missing expression" error. If I do: "insert into table 1, select ref(p), ref(d), ... from plaintiff p, defendant where p.name=...;" I get a "missing keyword VALUES" error.

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  • Improve SQL strategy - denormalize in object-children-images case

    - by fesja
    Hi, I have a Tour object which has many Place objects. For the list of tours, I want to show some info of the tour, the number of places of the tour, and three Place's images. Right one my SQL queries are (i'm using Doctrine with Symfony on MySQL) get Tour get Tour 1 places get Tour 2 places get Tour 3 places ... get Tour n places If I have a three Tour list, it's not so bad; but I'm sure it can get bad if I do a 10-20 tour-list. So, thinking on how to improve the queries I've thought of several measures: Having a place count cache Storing the urls of three images on a new tour field. The problem with 2. is that if I change the image, I have to check all the tours to update that image for another one. What solution do you think is best to scale the system in a near future? Any other suggestion. thanks!

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  • Is there an ORM with APIs to be used programatically?

    - by Kabeer
    Hello. Neither did not get any response for my previous question, nor enough views :) So here I am now framing my query afresh. Is there any ORM that offers APIs to be used programatically? In my situation, a user will be helped through a wizard to define some entities. Thereafter those entites will be created in a database in form of tables (there will of course be some improvization). I need an ORM that offers APIs for modeling and creating entities during application runtime and not just during design time. Mine is a .Net application, therefore I was looking at Entity Framework. However, to me it looked tied to Visual Studio (I may be wrong also as I am new to it). Any recommendations? Or alternative point of view?

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  • MVC Design Pattern to Combine Multiple Models for use

    - by roverred
    In my design, I have multiple models and each model has a controller. I need to use all the models to process some operation. Most examples I see are pretty simple with 1 view, 1 controller, and 1 model. How would you get all these models together? Only ways I can think of are 1) Have a top-level controller which has a reference to every controller. Those controllers will have a getter/setter function for their model. Does this violate MVC because every controller should have a model? 2) Have an Intermediate class to combine every model into a one model. Then you create a controller for that new super model. Do you know of any better ideas? Thanks.

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  • Tool to maintain a Data Mapping between two systems

    - by ktaylorjohn
    We have XML interfaces between multiple systems. An Enterprise Domain Model is missing in the overall architecture, hence the terms Product/Customer/User means different things to different systems. We currently use excel sheets to map the elements in incoming XML to what the actual Field means within our system. Additionally, it contains the values of Mandatory/Optional and length of each field. We call this the Data Dictionary. Any changes to the XML go through rounds of deliberation and updates to Word and Excel documents. Is there a better way to do this? Any tool/GUI based approach which all systems and owners can view?

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  • What is the effect of creating unit tests during development on time to develop as well as time spent in maintenance activities?

    - by jgauffin
    I'm a consultant and I am going to introduce unit tests to all developers at my client site. My goal is to ensure that all new applications should have unit tests for all classes created. The client has a problem with high maintenance costs from fixing bugs in their existing applications. Their applications have a life span from between 5-15 years in which they continuously add new features. I'm quite confident that they will benefit greatly from starting with unit tests. I'm interested in the effect of unit tests on the time and cost of development: How much time will writing unit tests as part of the development process add? How much time will be saved in maintenance activities (testing and debugging) by having good unit tests?

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