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• When is Googling it wrong?

  - by Drahcir

  I've been going through Stack Overflow for quite a bit now and noticed certain people (usually experienced programmers) frown upon Googling (researching) certain problems. Since I myself tend to use Google quite a bit to solve certain programming related issues I found certain comments rather demoralising. Now some of you may have come here trigger happy to delete this post but I needed some clarification. I usually Google things that usually syntax related that I would have never figured out on my own. For example I once wondered how to access the properties of a class that I didn't have a direct relationship to. So after a bit of research I discovered reflection and got what I wanted. Now in another scenario is learning a new language, in my case Silverlight were it differs in certain aspects of .NET compared to say ASP.NET. A few weeks ago I had no idea how to load another Silverlight page (usercontrol) and had to Google my way to the solution which I found wasn't as simple as I had imagined. In scenario three is were I myself frown up, that is just stealing a huge chunk of code to avoid doing the work yourself, for example paging a HTML table using JavaScript, where one just copies and pastes the JavasSript code without as much as trying to understand how it works. I do admit I have done this once or twice before for trivial tasks that had very little time limit and weren't all that important but most of the time still have to throw away what I found because it took too much time to adapt it and get what I wanted out of it. In the last scenario, I sometimes have a piece of code that I would be really unhappy about, as in I find it sloppy or too overcomplicated and try to look on the Internet to see other ways to tackle the same problem, let's say filtering through a table. With the knowledge I acquire I learned new coding practices that help me work more efficiently like "Do not repeat yourself" and such. Now in your opinion when do you find it wrong to use Google (or any other researching tool) to find a solution to your problem?

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• SQLAlchemy, one to many vs many to one

  - by sadvaw

  Dear Everyone, I have the following data: CREATE TABLE `groups` ( `bookID` INT NOT NULL, `groupID` INT NOT NULL, PRIMARY KEY(`bookID`), KEY( `groupID`) ); and a book table which basically has books( bookID, name, ... ), but WITHOUT groupID. There is no way for me to determine what the groupID is at the time of the insert for books. I want to do this in sqlalchemy. Hence I tried mapping Book to the books joined with groups on book.bookID=groups.bookID. I made the following: tb_groups = Table( 'groups', metadata, Column('bookID', Integer, ForeignKey('books.bookID'), primary_key=True ), Column('groupID', Integer), ) tb_books = Table( 'books', metadata, Column('bookID', Integer, primary_key=True), tb_joinedBookGroup = sql.join( tb_books, tb_groups, \ tb_books.c.bookID == tb_groups.c.bookID) and defined the following mapper: mapper( Group, tb_groups, properties={ 'books': relation(Book, backref='group') }) mapper( Book, tb_joinedBookGroup ) ... However, when I execute this piece of code, I realized that each book object has a field groups, which is a list, and each group object has books field which is a singular assigment. I think my definition here must have been causing sqlalchemy to be confused about the many-to-one vs one-to-many relationship. Can someone help me sort this out? My desired goal is g.books = [b, b, b, .. ] book.group = g, where g is an instance of group, and b is an instance of book

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• Saving a single entity instead of the entire context - revisited

  - by nite

  I’m looking for a way to have fine grained control over what is saved using Entity Framework, rather than the whole ObjectContext.SaveChanges(). My scenario is pretty straight forward, and I’m quite amazed not catered for in EF – pretty basic in NHibernate and all other data access paradigms I’ve seen. I’m generating a bunch of data (in a WPF UI) and allowing the user to fine tune what is proposed and choose what is actually committed to the database. For the proposed entities I’m: getting a bunch of reference entities (eg languages) via my objectcontext, creating the proposed entities and assigning these reference entities to them (as navigation properties), so by virtue of their relationship to the reference entities they’re implicitly added to the objectconext Trying to create & save individual entites based on the proposed entities. I figure this should be really simple & trivial but everything I’ve tried I’ve hit a brick wall, either I set up another objectcontext & add just the entity I need (it then tries to add the whole graph and fails as it’s on another objectcontext). I’ve tried MergeOptions = NoTracking on my reference entities to try to get the Attach/AddObject not to navigate through these to create a graph, no avail. I've removed the navigation properties from the reference entities. I've tried AcceptAllChanges, that works but pretty useless in practice as I do still want to track & save other entities. In a simple test, I can create 2 of my proposed entities, AddObject the one I want to save and then Detach the one I dont then call SaveChanges, this works but again not great in practice. Following are a few links to some of the nifty ideas which in the end don’t help in the end but illustrate the complexity of EF for something so simple. I’m really looking for a SaveSingle/SaveAtomic method, and think it’s a pretty reasonable & basic ask for any DAL, letalone a cutting edge ORM. http://stackoverflow.com/questions/1301460/saving-a-single-entity-instead-of-the-entire-context www.codeproject.com/KB/architecture/attachobjectgraph.aspx?fid=1534536&df=90&mpp=25&noise=3&sort=Position&view=Quick&select=3071122&fr=1 bernhardelbl.spaces.live.com/blog/cns!DB54AE2C5D84DB78!238.entry

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• How can I make Access think there is a primary key

  - by user3692757

  I have a table and I'm trying to join it with another table, but it doesn't have a distinctive primary key. The two tables do share similarities, “Acct” and “Location”. If I could concatenate “Acct&Location” it would become a primary key, but Access won’t let me make a primary key from a calculation. I provided a small sample below. Each hospital has an “Acct”, but the “Acct” will show up once for each “Location”. How can I make join these in a relationship? I connected the two in a relationships and tried to “Enforce Referential Integrity”, but it indicated “No unique index found for the referenced field of the primary key”. Also, if I run a “Find UnMatched Query” it doesn’t find anything. I think its because I can’t make it realize that in combination “Acct” and “Location” can be perceived as primary keys when used in conjunction of each other. Acct 1 2 3 1 2 3 1 2 3| Location ABI ABI ABI NHO NHO NHO NTX NTX NTX I tried to load an image to illustrate it better, but I haven't made enough post.

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• Howto: Access a second related model in a nested attribute builder block

  - by Joe Cairns

  I have a basic has_many through relationship: class Foo < ActiveRecord::Base has_many :bars, :dependent => :destroy has_many :wtfs :through => :bars accepts_nested_attributes_for :bars, :wtfs end On my crud forms I have a builder block for the wtf, but I need the label to come from the bar (an attribute called label for instance). What's the proper method to do this? Here's the most simple scaffold: <h1>New foo</h1> <% form_for(@foo) do |f| %> <%= f.error_messages %> <p> <%= f.label :name %><br /> <%= f.text_field :name %> </p> <h2>Bars</h2> <% f.fields_for :wtfs do |builder| %> <%= builder.hidden_field :bar_id %> <p> <%= builder.text_field :wtf_data_i_need_to_set %> </p> <% end %> <p> <%= f.submit 'Create' %> </p> <% end %> <%= link_to 'Back', foos_path %>

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• assembling an object graph without an ORM -- in the service layer or data layer?

  - by Hans Gruber

  At my current gig, our persistence layer uses IBatis going against SQL Server stored procedures (puke). IMHO, this approach has many disadvantages over the use of a "true" ORM such NHibernate or EF, but the one I'm trying to address here revolves around all the boilerplate code needed to map data from a result set into an object graph. Say I have the following DTO object graph I want to return to my presentation layer: IEnumerable<CustomerDTO> |--> IEnumerable<AddressDTO> |--> LatestOrderDTO The way I've implemented this is to have a discrete method in my DAO class to return each IEnumerable<*DTO>, and then have my service class be responsible for orchestrating the calls to the DAO. It then returns the fully assembled object graph to the client: public class SomeService(){ public SomeService(IDao someDao){ this._someDao = someDao; } public IEnumerable<CustomerDTO> ListCustomersForHistory(int brokerId){ var customers = _someDao.ListCustomersForBroker(brokerId); foreach (customer in customers){ customer.Addresses = someDao.ListCustomersAddresses(brokerId); customer.LatestOrder = someDao.GetCustomerLatestOrder(brokerId); } } return customers; } My question is should this logic belong in the service layer or the should I make my DAO such that it instead returns the assembled object graph. If I was using NHibernate, I assume that this kind of relationship association between objects comes for "free"?

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• Core Data Predicates with Subclassed NSManagedObjects

  - by coneybeare

  I have an AUDIO class. This audio has a SOUND_A subclass and a SOUND_B subclass. This is all done correctly and is working fine. I have another model, lets call it PLAYLIST_JOIN, and this can contain (in the real world) SOUND_A's and SOUND_B's, so we give it a relationship of AUDIO and PLAYLIST. This all works in the app. The problem I am having now is querying the PLAYLIST_JOIN table with an NSPredicate. What I want to do is find an exact PLAYLIST_JOIN item by giving it 2 keys in the predicate sound_a._sound_a_id = %@ && playlist.playlist_id = %@ and sound_b.sound_b_id = %@ && playlist.playlist_id = %@ The main problem is that because the table does not store sound_a and sound_b, but stored audio, I cannot use this syntax. I do not have the option of reorganizing the sound_a and sound_b to use the same _id attribute name, so how do I do this? Can I pass a method to the predicate? something like this: [audio getID] = %@ && playlist_id = %@

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• C++ socket protocol design issue (ring inclusion)

  - by Martin Lauridsen

  So I have these two classes, mpqs_client and client_protocol. The mpqs_client class handles a Boost socket connection to a server (sending and receiving messages with some specific format. Upon receiving a message, it calls a static method, parse_message(..), in the class client_protocol, and this method should analyse the message received and perform some corresponding action. Given some specific input, the parse_message method needs to send some data back to the server. As mentioned, this happens through the class mpqs_client. So I could, from mpqs_client, pass "this" to parse_message(..) in client_protocol. However, this leads to a two-way association relationship between the two classes. Something which I reckon is not desireable. Also, to implement this, I would need to include the other in each one, and this gives me a terrible pain. I am thinking this is more of a design issue. What is the best solution here? Code is posted below. Class mpqs_client: #include "mpqs_client.h" mpqs_client::mpqs_client(boost::asio::io_service& io_service, tcp::resolver::iterator endpoint_iterator) : io_service_(io_service), socket_(io_service) { ... } ... void mpqs_client::write(const network_message& msg) { io_service_.post(boost::bind(&mpqs_client::do_write, this, msg)); } Class client_protocol: #include "../network_message.hpp" #include "../protocol_consts.h" class client_protocol { public: static void parse_message(network_message& msg, mpqs_sieve **instance_, mpqs_client &client_) { ... switch (type) { case MPQS_DATA: ... break; case POLYNOMIAL_DATA: ... break; default: break; } }

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• Compile time type determination in C++

  - by dicroce

  A coworker recently showed me some code that he found online. It appears to allow compile time determination of whether a type has an "is a" relationship with another type. I think this is totally awesome, but I have to admit that I'm clueless as to how this actually works. Can anyone explain this to me? template<typename BaseT, typename DerivedT> inline bool isRelated(const DerivedT&) { DerivedT derived(); char test(const BaseT&); // sizeof(test()) == sizeof(char) char (&test(...))[2]; // sizeof(test()) == sizeof(char[2]) struct conversion { enum { exists = (sizeof(test(derived())) == sizeof(char)) }; }; return conversion::exists; } Once this function is defined, you can use it like this: #include <iostream> class base {}; class derived : public base {}; class unrelated {}; int main() { base b; derived d; unrelated u; if( isRelated<base>( b ) ) std::cout << "b is related to base" << std::endl; if( isRelated<base>( d ) ) std::cout << "d is related to base" << std::endl; if( !isRelated<base>( u ) ) std::cout << "u is not related to base" << std::endl; }

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• What's the difference between the [OptionalField] and [NonSerialized]

  - by IbrarMumtaz

  I came across this question on transcender: What should you apply to a field if its value is not required during deserialization? Me = [NonSerialized], ANSWER = [OptionalField] My gut reaction was NonSerialised, I have no idea why but in the space of 5 seconds thats what I thought but to my surprise, Transcender says I am wrong. OK fair enough .... but why? looking more closely at the question I have a good idea what to look out for as far as the [Nonseralized] attribute is concerned but still I would really like this clearing up. As far as I can tell the former has relationship with versioning conflicts between newer and older versions of the same assembly. The later is more concerned with not serializing a field FULLSTOP. Is there anything else that might pick these two apart? MSDN does not really say much about this as they both are used on the BinaryFormatters and SoapFormatter with the XMLFormatter using the XMLIgnoreAttribute. My second question is can you mix and match either one of the two attributes ... I am yet to use them as I have not had an excuse to mess about with them. So my curiosity can only go so far. Just throwing this one out there, but does my answer have something to do with the way [OnDeserialized] and the IdeserilizationCallback interface is implemented???? Am guessing here .... Thanks In Advance UPDATE: I know that optional field attribute does not serialize the value held by a data member but NonSerialized will not even serialise the data member or its value. That sounds about a right???? That's all I got on these two attributes.

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• access properties of current model in has_many declaration

  - by seth.vargo

  Hello, I didn't exactly know how to pose this question other than through example... I have a class we will call Foo. Foo :has_many Bar. Foo has a boolean attribute called randomize that determines the order of the the Bars in the :has_many relationship: class CreateFoo < ActiveRecord::Migration def self.up create_table :foos do |t| t.string :name t.boolean :randomize, :default => false end end end   class CreateBar < ActiveRecord::Migration def self.up create_table :bars do |t| t.string :name t.references :foo end end end   class Bar < ActiveRecord::Base belongs_to :foo end   class Foo < ActiveRecord::Base # this is the line that doesn't work has_many :bars, :order => self.randomize ? 'RAND()' : 'id' end How do I access properties of self in the has_many declaration? Things I've tried and failed: creating a method of Foo that returns the correct string creating a lambda function crying Is this possible? UPDATE The problem seems to be that the class in :has_many ISN'T of type Foo: undefined method `randomize' for #<Class:0x1076fbf78> is one of the errors I get. Note that its a general Class, not a Foo object... Why??

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• data filter using dataloadoptions

  - by Tassadaque

  Using dataloadoptions i have tried the following example Northwnd db = new Northwnd(@"northwnd.mdf"); // Preload Orders for Customer. // One directive per relationship to be preloaded. DataLoadOptions ds = new DataLoadOptions(); ds.LoadWith<Customer>(c => c.Orders); ds.AssociateWith<Customer> (c => c.Orders.Where(p => p.ShippedDate != DateTime.Today)); db.LoadOptions = ds; var custQuery = from cust in db.Customers where cust.City == "London" select cust; foreach (Customer custObj in custQuery) { Console.WriteLine("Customer ID: {0}", custObj.CustomerID); foreach (Order ord in custObj.Orders) { Console.WriteLine("\tOrder ID: {0}", ord.OrderID); foreach (OrderDetail detail in ord.OrderDetails) { Console.WriteLine("\t\tProduct ID: {0}", detail.ProductID); } } } Now i need to ask how can i display Category ID and Category Name of the productID (i am supposing that One product can be in at most one category) by extending the above example Regards

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• Doctrine: Unable to execute either CROSS JOIN or SELECT FROM Table1, Table2?

  - by ropstah

  Using Doctrine I'm trying to execute either a 1. CROSS JOIN statement or 2. a SELECT FROM Table1, Table2 statement. Both seem to fail. The CROSS JOIN does execute, however the results are just wrong compared to executing in Navicat. The multiple table SELECT doesn't event execute because Doctrine automatically tries to LEFT JOIN the second table. The cross join statement (this runs, however it doesn't include the joined records where the refClass User_Setting doesn't have a value): $q = new Doctrine_RawSql(); $q->select('{s.*}, {us.*}') ->from('User u CROSS JOIN Setting s LEFT JOIN User_Setting us ON us.usr_auto_key = u.usr_auto_key AND us.set_auto_key = s.set_auto_key') ->addComponent('u', 'User u') ->addComponent('s', 'Setting s') ->addComponent('us', 'u.User_Setting us') ->where('s.sct_auto_key = ? AND u.usr_auto_key = ?',array(1, $this->usr_auto_key)); And the select from multiple tables (this doesn't event run. It does not spot the many-many relationship between User and Setting in the first ->from() part and throws an exception: "User_Setting" with an alias of "us" in your query does not reference the parent component it is related to.): $q = new Doctrine_RawSql(); $q->select('{s.*}, {us.*}') ->from('User u, Setting s LEFT JOIN User_Setting us ON us.usr_auto_key = u.usr_auto_key AND us.set_auto_key = s.set_auto_key') ->addComponent('u', 'User u') ->addComponent('s', 'Setting s') ->addComponent('us', 'u.User_Setting us') ->where('s.sct_auto_key = ? AND u.usr_auto_key = ?',array(1, $this->usr_auto_key));

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• Django Datetime field question

  - by Shehzad009

  Hello I have been having a problem with django while trying to work with datetime. In my webapp I have a table like so when I run server. ID Owing 1 -100 (All the same value) 2 -100 3 -100 . . . . . . It has in one column Invoice id and the other owing. One-one relationship as well. sow for example owing value for 1 is 100. Unfortunately, this is where it all goes wrong because throughout column (Owing), it is giving me the owing value for ID=1. I want each ID to give me their owing value. Here is my view. I also wonder if I may need a for loop somewhere as well. def homepage(request): invoices_list = Invoice.objects.all() invoice_name = invoices_list[0].client_contract_number.client_number.name invoice_gross = invoices_list[0].invoice_gross payment_date = invoices_list[0].payment_date if payment_date <= datetime.now(): owing = invoice_gross if payment_date > datetime.now(): owing = 0 else: owing= 0 return render_to_response(('index.html', locals()), {'invoices_list': invoices_list ,'invoice_number':invoice_number, 'invoice_name':invoice_name, 'invoice_gross':invoice_gross, 'payment_date':payment_date, 'owing': owing}, context_instance=RequestContext(request)) EDIT: Here is my template. The thing is the function owing is not in my models so saying {{invoices.owing}} wont work. {% for invoices in invoices_list %} <tr> <td>{{invoices.invoice_number}}</td> <td>{{invoices.invoice_contact}}</td> <td>{{invoices.client_contract_number}}</td> <td>{{invoices.payment_date|date:"d M Y"}}</td> <td>{{invoices.invoice_gross}}</td> <td>{{owing}}</td> {% endfor %}

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• EF Code First - Relationships

  - by CaffGeek

  I have these classes public class EntityBase : IEntity { public int Id { get; set; } public DateTime Created { get; set; } public string CreatedBy { get; set; } public DateTime Updated { get; set; } public string UpdatedBy { get; set; } } public class EftInterface : EntityBase { public string Name { get; set; } public Provider Provider { get; set; } public List<BusinessUnit> BusinessUnits { get; set; } } public class Provider : EntityBase, IEntity { public string Name { get; set; } public decimal DefaultDebitLimit { get; set; } public decimal DefaultCreditLimit { get; set; } public decimal TreasuryDebitLimit { get; set; } public decimal TreasuryCreditLimit { get; set; } } public class BusinessUnit : EntityBase { public string Name { get; set; } } An interface, is really a Provider, with a collection of Business Units. The issue is that while my db model ends up having a correct EftInterfaces table, with a FK to Provider_Id, the BusinessUnits table has a FK to EftInterface_Id. But, a BusinessUnit can be included in more than one EftInterface. I need a many to many relationship. A BusinessUnit can be part of many EftInterfaces, and an EftInterface can contain many BusinessUnits. How can I get CodeFirst to generate the many-to-many table?

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• Can a PHP object respond to an undefined method?

  - by Nathan Long

  Rails relies on some of the neat aspects of Ruby. One of those is the ability to respond to an undefined method. Consider a relationship between Dog and Owner. Owner has_many :dogs and Dog belongs_to :owner. If you go into script/console, get a dog object with fido = Dog.find(1), and look at that object, you won't see a method or attribute called Owner. What you will see is an owner_id. And if you ask for fido.owner, the object will do something like this (at least, this is how it appears to me): I'm being asked for my .owner attribute. I don't have one of those! Before I throw a NoMethodError, do I have a rule about how to deal with this? Yes, I do: I should check and see if I have an owner_id. I do! OK, then I'll do a join and return that owner object. PHP's documentation is - ahem - a bit lacking sometimes, so I wonder if anyone here knows the answer to this: Can I define similar behavior for objects in PHP? If not, do you know of a workaround for flexible model joins like these?

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• Trouble accessing data in relationships in Ember

  - by user3618430

  I'm having trouble saving data in this model relationship. My models are as follows: App.Flow = DS.Model.extend({ title: DS.attr('string'), content: DS.attr('string'), isCustom: DS.attr('boolean'), params: DS.hasMany('parameter', {async: true}) }); App.Parameter = DS.Model.extend({ flow: DS.belongsTo('flow'), param: DS.attr('string'), param_tooltip: DS.attr('string'), param_value: DS.attr('string') }); As you can see, I want Flows to have multiple Parameters. I have a rudimentary setup using Flow and Parameter fixtures, which behave as expected in the templates. However, when I try to create new ones in the controller, I have trouble setting the flow and parameter values correctly. var p = this.store.createRecord('parameter', { param: "foo", param_tooltip: "world", param_value: "hello" }); var f = this.store.createRecord('flow', { title: 'job', content: title, isCustom: true, params: [p] // doesn't seem to work }); f.set('params', [p]); // doesn't seem to work p.set('flow', f); // also doesn't seem to work // Save the new model p.save(); f.save(); I've tried a lot of solutions after staring at this and StackOverflow for a while (not just the ones listed). I'm not really sure what to try next. One thing that I noticed in the Ember inspector was that the ids of these created elements were not integers (they were something like the string 'fixture_0'), but I'm not really sure why that would be, whether its related, or how to fix it. Thanks!

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• Populate JOIN into a list in one database query

  - by axio

  I am trying to get the records from the 'many' table of a one-to-many relationship and add them as a list to the relevant record from the 'one' table. I am also trying to do this in a single database request. Code derived from http://stackoverflow.com/questions/1580199/linq-to-sql-populate-join-result-into-a-list almost achieves the intended result, but makes one database request per entry in the 'one' table which is unacceptable. That failing code is here: var res = from variable in _dc.GetTable<VARIABLE>() select new { x = variable, y = variable.VARIABLE_VALUEs }; However if I do a similar query but loop through all the results, then only a single database request is made. This code achieves all goals: var res = from variable in _dc.GetTable<VARIABLE>() select variable; List<GDO.Variable> output = new List<GDO.Variable>(); foreach (var v2 in res) { List<GDO.VariableValue> values = new List<GDO.VariableValue>(); foreach (var vv in v2.VARIABLE_VALUEs) { values.Add(VariableValue.EntityToGDO(vv)); } output.Add(EntityToGDO(v2)); output[output.Count - 1].VariableValues = values; } However the latter code is ugly as hell, and it really feels like something that should be do-able in a single linq query. So, how can this be done in a single linq query that makes only a single database query? In both cases the table is set to preload using the following code: _dc = _db.CreateLinqDataContext(); var loadOptions = new DataLoadOptions(); loadOptions.LoadWith<VARIABLE>(v => v.VARIABLE_VALUEs); _dc.LoadOptions = loadOptions; I am using .NET 3.5, and the database back-end was generated using SqlMetal.

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• How add logic to Views? Ruby on Rails

  - by Gotjosh

  Right now I'm building a project management app in rails, here is some background info: Right now i have 2 models, one is User and the other one is Client. Clients and Users have a one-to-one relationship (client - has_one and user - belongs_to which means that the foreign key it's in the users table) So what I'm trying to do it's once you add a client you can actually add credentials (add an user) to that client, in order to do so all the clients are being displayed with a link next to that client's name meaning that you can actually create credentials for that client. What i can't figure it out how to do is, that if you actually have credentials in the database (meaning that there's a record in the users table with your client id) then don't display that link. Here's what i thought that would work <% for client in @client%> <h5> <h4><%= client.id %></h4> <a href="/clients/<%= client.id %>"><%= client.name %></a> <% for user in @user %> <% if user.client_id = client.id %> <a href="/clients/<%= client.id %>/user/new">Credentials</a> <%end%> <% end %> </h5> <% end %> And here's the controller: def index @client = Client.find_all_by_admin(0) @user = User.find(:all) end but instead it just puts the link the amount of times per records in the user table. Any help?

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• Complex sorting on MySQL database

  - by ChrisR

  I'm facing the following situation. We've got an CMS with an entity with translations. These translations are stored in a different table with a one-to-many relationship. For example newsarticles and newsarticle_translations. The amount of available languages is dynamically determined by the same CMS. When entering a new newsarticle the editor is required to enter at least one translation, which one of the available languages he chooses is up to him. In the newsarticle overview in our CMS we would like to show a column with the (translated) article title, but since none of the languages are mandatory (one of them is mandatory but i don't know which one) i don't really know how to construct my mysql query to select a title for each newsarticle, regardless of the entered language. And to make it all a little harder, our manager asked for the possibilty to also be able to sort on title, so fetching the translations in a separate query is ruled out as far as i know. Anyone has an idea on how to solve this in the most efficient way? Here are my table schema's it it might help > desc news; +-----------------+----------------+------+-----+-------------------+----------------+ | Field | Type | Null | Key | Default | Extra | +-----------------+----------------+------+-----+-------------------+----------------+ | id | int(10) | NO | PRI | NULL | auto_increment | | category_id | int(1) | YES | | NULL | | | created | timestamp | NO | | CURRENT_TIMESTAMP | | | user_id | int(10) | YES | | NULL | | +-----------------+----------------+------+-----+-------------------+----------------+ > desc news_translations; +-----------------+------------------+------+-----+---------+----------------+ | Field | Type | Null | Key | Default | Extra | +-----------------+------------------+------+-----+---------+----------------+ | id | int(10) unsigned | NO | PRI | NULL | auto_increment | | enabled | tinyint(1) | NO | | 0 | | | news_id | int(1) unsigned | NO | | NULL | | | title | varchar(255) | NO | | | | | summary | text | YES | | NULL | | | body | text | NO | | NULL | | | language | varchar(2) | NO | | NULL | | +-----------------+------------------+------+-----+---------+----------------+ PS: i've though about subqueries and coalesce() solutions but those seem rather dirty tricks, wondering if something better is know that i'm not thinking of?

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• Entity framework self referencing loop detected

  - by Lyd0n

  I have a strange error. I'm experimenting with a .NET 4.5 Web API, Entity Framework and MS SQL Server. I've already created the database and set up the correct primary and foreign keys and relationships. I've created a .edmx model and imported two tables: Employee and Department. A department can have many employees and this relationship exists. I created a new controller called EmployeeController using the scaffolding options to create an API controller with read/write actions using Entity Framework. In the wizard, selected Employee as the model and the correct entity for the data context. The method that is created looks like this: // GET api/Employee public IEnumerable<Employee> GetEmployees() { var employees = db.Employees.Include(e => e.Department); return employees.AsEnumerable(); } When I call my API via /api/Employee, I get this error: ...The 'ObjectContent`1' type failed to serialize the response body for content type 'application/json; ...System.InvalidOperationException","StackTrace":null,"InnerException":{"Message":"An error has occurred.","ExceptionMessage":"Self referencing loop detected with type 'System.Data.Entity.DynamicProxies.Employee_5D80AD978BC68A1D8BD675852F94E8B550F4CB150ADB8649E8998B7F95422552'. Path '[0].Department.Employees'.","ExceptionType":"Newtonsoft.Json.JsonSerializationException","StackTrace":" ... Why is it self referencing [0].Department.Employees? That doesn't make a whole lot of sense. I would expect this to happen if I had circular referencing in my database but this is a very simple example. What could be going wrong?

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• JPA + EJB + JSF: how can design complicated query

  - by Harry Pham

  I am using netbean 6.8 btw. Let say that I have 4 different tables: Company, Facility, Project, and Document. So the relationship is this. A company can have multiple facilities. A facility can have multiple projects, and a project can have multiple documents. Company: +companyNum: PK +facilityNum: FK Facility: +facilityNum: PK +projectNum: FK Project: +projectNum: PK +drawingNum: FK So when I create Entity Class From Database in netbean 6.8, I have 4 entity classes that named after the above 4 tables. So if I want to see all the Document in the database, then it is easy. In my SessionBean, I would do this: @PersistenceContext private EntityManager em; List<Document> documents = em.createNamedQuery("Document.findAll").getResultList(); However, that is not all what I need. Let say that I want to know all the Document from a particular Company, or all the Document from a particular Project from a particular Facility from a particular Company. I am very new to JPA + EJB + JSF as a whole. Please help me out.

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• Modeling Buyers & Sellers in a Rails Ecommerce App

  - by MikeH

  I'm building a Rails app that has Etsy.com style functionality. In other words, it's like a mall. There are many buyers and many sellers. I'm torn about how to model the sellers. Key facts: There won't be many sellers. Perhaps less than 20 sellers in total. There will be many buyers. Hopefully many thousands :) I already have a standard user model in place with account creation and roles. I've created a 'role' of 'seller', which the admin will manually apply to the proper users. Since we'll have very few sellers, this is not an issue. I'm considering two approaches: (1) Create a 'store' model, which will contain all the relevant store information. Products would :belong_to :store, rather than belonging to the seller. The relationship between the user and store models would be: user :has_one store. My main problem with this is that I've always found has_one associations to be a little funky, and I usually try to avoid them. The app is fairly complex, and I'm worried about running into a cascade of problems connected to the has_one association as I get further along into development. (2) Simply include the relevant 'store' information as part of the user model. But in this case, the store-related db columns would only apply to a very small percentage of users since very few users will also be sellers. I'm not sure if this is a valid concern or not. It's very possible that I'm thinking about this incorrectly. I appreciate any thoughts. Thanks.

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• Defining and using controller methods in ember.js

  - by OriginalEXE

  first of all, I am total noob when it comes to OOP in JS, this is new to me so treat me like a noob. I am building my first ember.js application and I am stuck (not the first time but I would get unstuck by myself, this is a tough one though). I have two models: forms entries Entries is of course in (one to many) relationship to forms, so each form can have as many properties. Form properties: id : DS.attr( 'number' ), title : DS.attr( 'string' ), views : DS.attr( 'number' ), conversion : DS.attr( 'number' ), entries : DS.hasMany( 'entry' ) Entry properties: id : DS.attr( 'number' ), parent_id: DS.belongsTo( 'form' ) Now, I have forms route that displays all forms in tabled view, and each table row has some info like form id, name etc. and that works great. What I wanted to do is display the number of entries each form has. I figured I should do that via controller, so here is my controller now: // Form controller App.FormController = Ember.ObjectController.extend({ entriescount: function() { var entries = this.get( 'store').find( 'entry' ); return entries.filterBy( 'parent_id', this.get( 'id' ) ).get( 'length' ); }.property( '[email protected]_id') }); Now for some reason, when I use {{entriescount}} in {{#each}} loop, this returns nothing. It also returns nothing in single form route. Note that in both cases, {{title}} for example works. I am wondering, am I going the right way by using controller for this, and how do I get controller to output the data. Thanks

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• How can I set the tab on a webpage depending on which page you come from in ASP.Net MVC?

  - by uriDium

  I have a rather large entity. It has a parent relationship with many different child tables. Each of the child tables I have represented as a tab (luckily it makes sense and looks nice and makes things easier to navigate). If the users wants to add a new child row, they go the particular tab, and there they see a list of rows which is owned by the parent and they can do the usual CRUD. The CRUD takes them to a new controller and action and passes the ID of the parent to the action. (This is as far as I can tell what I was meant to do, any other ideas??) When they have finsihed they click save and it takes them back to the original page BUT I want it to automatically go to the right tab. How can I do this? I am using Jquery UI tabs, ASP.Net MVC 2.0. One idea I had was to just go back to the bookmark (the href part with the #, for e.g. /Parent/Details/4/#tabname). Apparently JQuery UI tabs can handle this. Or to set the tab name as part of the query string (/Parent/Details/4?tab=name) What is the best practise here?

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