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• CakePhp: model recursive associations and find

  - by Petecocoon

  Hello to everybody! I've some trouble with a find() on a model on CakePhp. I have three model relationed in this way: Project(some_fields, item_id) ------belongsTo----- Item(some_fields, item_id) ------belongsTo----- User(some_fields campi, nickname) I need to do a find() and retrieve all fields from project, a field from Item and the nickname field from User. This is my code: $this->set('projects', $this->Project->find('all', array('recursive' => 2))); but my output doesn't contains the user object. I've tried with Containable behaviour but the output is the same. What is broken? Many many Thanks Peter

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• How best can I extract a logical model from a physical DB model

  - by Dean

  We have made substantial changes to our physical DB, now as it is the ne dof the project I would like to abstract a logical model from this, to allow me to generate schemas for both Oracle and SQL Server. Can anyone guide me as to the best way to achieve this. I was hoping TOAD data modeller would help but I can't seem to see any options to do what I require?

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• Define Rails Model Persistent Attributes in Model File

  - by Kevin Sylvestre

  I recently played with MongoDB in Rails using Mongoid. I like the ability to define attributes for models within the model file (as opposed to in migrations): class Person include Mongoid::Document field :name, :type => String field :birthday, :type => Date end For projects that cannot use a schema-less database, does a similar feature exist? Any gems or plugins that generate schemas from a similar syntax would be greatly appreciated. Thanks.

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• Creating relationship between two model instances

  - by Lowgain

  This is probably pretty simple, but here: Say I've got two models, Thing and Tag class Thing < ActiveRecord::Base has_and_belongs_to_many :tags end class Tag < ActiveRecord::Base has_and_belongs_to_many :things end And I have an instance of each. I want to link them. Can I do something like: @thing = Thing.find(1) @tag = Tag.find(1) @thing.tags.add(@tag) If not, what is the best way to do this? Thanks!

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• Interview question: difference between object and object-oriented languages.

  - by Bar

  My friend was asked the following question: what's the difference between object language and object-oriented language? It's a little unintelligible question. What does term «object language» correspond to? Does that mean «pure» object-oriented language, like the Wikipedia article says: Languages called "pure" OO languages, because everything in them is treated consistently as an object, from primitives such as characters and punctuation, all the way up to whole classes, prototypes, blocks, modules, etc. They were designed specifically to facilitate, even enforce, OO methods. Examples: Smalltalk, Eiffel, Ruby, JADE, VB.NET.

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• Can't call method in model table class using Doctrine with Zend Framework

  - by Jeremy Hicks

  I'm using Doctrine with Zend Framework. For my model, I'm using a base class, the regular class (which extends the base class), and a table class. In my table class, I've created a method which does a query for records with a specific value for one of the fields in my model. When I try and call this method from my controller, I get an error message saying, "Message: Unknown method Doctrine_Table::getCreditPurchases". Is there something else I need to do to call functions in my table class? Here is my code: class Model_CreditTable extends Doctrine_Table { /** * Returns an instance of this class. * * @return object Model_CreditTable */ public static function getInstance() { return Doctrine_Core::getTable('Model_Credit'); } public function getCreditPurchases($id) { $q = $this->createQuery('c') ->where('c.buyer_id = ?', $id); return $q->fetchArray(); } } // And then in my controller method I have... $this->view->credits = Doctrine_Core::getTable('Model_Credit')->getCreditPurchases($ns->id);

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• Getting the value from an array in the model in rails

  - by slythic

  Hi all, I have a relatively simple problem. I have a model named Item which I've added a status field. The status field will only have two options (Lost or Found). So I created the following array in my Item model: STATUS = [ [1, "Lost"], [2, "Found"]] In my form view I added the following code which works great: <%= collection_select :item, :status, Item::STATUS, :first, :last, {:include_blank => 'Select status'} %> This stores the numeric id (1 or 2) of the status in the database. However, in my show view I can't figure out how to convert from the numeric id (again, 1 or 2) to the text equivalent of Lost or Found. Any ideas on how to get this to work? Is there a better way to go about this? Many thanks, Tony

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• Rails Model has_many with multiple foreign_keys

  - by Kenzie

  Relatively new to rails and trying to model a very simple family "tree" with a single Person model that has a name, gender, father_id and mother_id (2 parents). Below is basically what I want to do, but obviously I can't repeat the :children in a has_many (the first gets overwritten). class Person < ActiveRecord::Base belongs_to :father, :class_name => 'Person' belongs_to :mother, :class_name => 'Person' has_many :children, :class_name => 'Person', :foreign_key => 'mother_id' has_many :children, :class_name => 'Person', :foreign_key => 'father_id' end Is there a simple way to use has_many with 2 foreign keys, or maybe change the foreign key based on the object's gender? Or is there another/better way altogether? Thanks!

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• RoR model field without validators, has*, delegates, etc

  - by jackr

  How can I declare a field, in the Rails model, when it doesn't have any "has_" relations, or validations, or delegations? I just need to ensure its existence and column width in the schema. Currently, I have no mention of the field in the "schema section" of the model file, but it's referenced in various methods that use it, and this seems to work. However, depending on my exact creation workflow, the underlying database table may be created as t.binary "field_name", :limit => 32 or t.binary "field_name", :limit => 255 This is not a restriction on the value (any binary value is valid, even NULL), only on the table column declaration. As it happens, 32 is enough -- it never receives any larger value, it's only ever written to like this: self.field_name = SecureRandom.random_bytes(32)

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• Is the provider model using the factory pattern?

  - by Blankman

  Hi, Is the provider model really just the factory pattern?

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• Return an Object in Java

  - by digby12

  I've been struggling to work out how to return an object. I have the following array of objects. ArrayList<Object> favourites; I want to find an object in the array based on it's "description" property. public Item finditem(String description) { for (Object x : favourites) { if(description.equals(x.getDescription())) { return Object x; else { return null; Can someone please show me how I would write this code. Thanks.

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• Rails: Creating subfolders in model?

  - by keruilin

  I'm going to have a ton of subclasses, so want to organize them under a subfolder called stream. I added the following line to the environment.rb so that all classes in the subfolder would be loaded: Rails::Initializer.run do |config| ... config.load_paths += Dir["#{RAILS_ROOT}/app/models/*"].find_all { |f| File.stat(f).directory? } ... end I thought this would solve the issue in which by convention the model class is namespaced into an according module. However, when I try to call one of the classes called stream in the stream folder, I get the following error: NoMethodError: undefined method `new' for Stream:Module from (irb):28 from /usr/local/bin/irb:12:in `<main>' Here's the model for the parent and one child: class Stream end class EventStream < Stream end Any idea what the issue is?

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• OpenERP model tracking external resource, hooking into parent's copy() or copy_data()

  - by CB.

  I have added a new model (call it crm_lead_external) that is linked via a new one2many on crm_lead. Thus, my module has two models defined: an updated crm_lead (with _name=crm_lead) and a new crm_lead_external. This external model tracks a file and as such has a 'filename' field. I also created a unique SQL index on this filename field. This is part of my module: def copy(self, cr, uid, id, default=None, context=None): if not default: default = {} default.update({ 'state': 'new', 'filename': '', }) ret = super(crm_lead_external, self).copy(cr, uid, id, default, context=context) #do file copy return ret The intent here is to allow an external entity to be duplicated, but to retarget the file path. Now, if I click duplicate on the Lead, I get an IntegrityError on my unique constraint. Is there a particular reason why copy() isn't being called? Should I add this logic to copy_data()? Myst I really override copy() for the lead? Thanks in advance.

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• Ruby on Rails Increment Counter in Model

  - by febs

  I'm attempting to increment a counter in my User table from another model. class Count < ActiveRecord::Base belongs_to :user after_create :update_count def update_count user = User.find(self.user_id) user.increment(:count) end end So when count is created the goal would be to increment a counter column for that user. Currently it refuses to get the user after creation and I get a nil error. I'm using devise for my Users Is this the right (best practice) place to do it? I had it working in the controllers, but wanted to clean it up. I'm very inexperienced with Model callbacks.

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• how to create model based Acl

  - by user1400

  hello all if we have some modules in our application how we could create Model based ACL by zend framework for each models? thanks

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• How Do You Actually Model Data?

  Since the 1970’s Developers, Analysts and DBAs have been able to represent concepts and relations in the form of data through the use of generic symbols.  But what is data modeling?  The first time I actually heard this term I could not understand why anyone would want to display a computer on a fashion show runway. Hey, what do you expect? At that time I was a freshman in community college, and obviously this was a long time ago.  I have since had the chance to learn what data modeling truly is through using it. Data modeling is a process of breaking down information and/or requirements in to common categories called objects. Once objects start being defined then relationships start to form based on dependencies found amongst other existing objects.  Currently, there are several tools on the market that help data designer actually map out objects and their relationships through the use of symbols and lines.  These diagrams allow for designs to be review from several perspectives so that designers can ensure that they have the optimal data design for their project and that the design is flexible enough to allow for potential changes and/or extension in the future. Additionally these basic models can always be further refined to show different levels of details depending on the target audience through the use of three different types of models. Conceptual Data Model(CDM)Conceptual Data Models include all key entities and relationships giving a viewer a high level understanding of attributes. Conceptual data model are created by gathering and analyzing information from various sources pertaining to a project during the typical planning phase of a project. Logical Data Model (LDM)Logical Data Models are conceptual data models that have been expanded to include implementation details pertaining to the data that it will store. Additionally, this model typically represents an origination’s business requirements and business rules by defining various attribute data types and relationships regarding each entity. This additional information can be directly translated to the Physical Data Model which reduces the actual time need to implement it. Physical Data Model(PDMs)Physical Data Model are transformed Logical Data Models that include the necessary tables, columns, relationships, database properties for the creation of a database. This model also allows for considerations regarding performance, indexing and denormalization that are applied through database rules, data integrity. Further expanding on why we actually use models in modern application/database development can be seen in the benefits that data modeling provides for data modelers and projects themselves, Benefits of Data Modeling according to Applied Information Science Abstraction that allows data designers remove concepts and ideas form hard facts in the form of data. This gives the data designers the ability to express general concepts and/or ideas in a generic form through the use of symbols to represent data items and the relationships between the items. Transparency through the use of data models allows complex ideas to be translated in to simple symbols so that the concept can be understood by all viewpoints and limits the amount of confusion and misunderstanding. Effectiveness in regards to tuning a model for acceptable performance while maintaining affordable operational costs. In addition it allows systems to be built on a solid foundation in terms of data. I shudder at the thought of a world without data modeling, think about it? Data is everywhere in our lives. Data modeling allows for optimizing a design for performance and the reduction of duplication. If one was to design a database without data modeling then I would think that the first things to get impacted would be database performance due to poorly designed database and there would be greater chances of unnecessary data duplication that would also play in to the excessive query times because unneeded records would need to be processed. You could say that a data designer designing a database is like a box of chocolates. You will never know what kind of database you will get until after it is built.

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• Trouble accessing fields of a serialized object in Java

  - by typoknig

  I have instantized a class that implements Serializable and I am trying to stream that object like this: try{ Socket socket = new Socket("localhost", 8000); ObjectOutputStream toServer = new ObjectOutputStream(socket.getOutputStream()); toServer.writeObject(myObject); } catch (IOException ex) { System.err.println(ex); } All good so far right? Then I am trying to read the fields of that object like this: //This is an inner class class HandleClient implements Runnable{ private ObjectInputStream fromClient; private Socket socket; // This socket was established earlier try { fromClient = new ObjectInputStream(socket.getInputStream()); GetField inputObjectFields = fromClient.readFields(); double myFristVariable = inputObjectFields.get("myFirstVariable", 0); int mySecondVariable = inputObjectFields.get("mySecondVariable", 0); //do stuff } catch (IOException ex) { System.err.println(ex); } catch (ClassNotFoundException ex) { System.err.println(ex); } finally { try { fromClient.close(); } catch (Exception ex) { ex.printStackTrace(); } } } But I always get the error: java.io.NotActiveException: not in call to readObject This is my first time streaming objects instead of primitive data types, what am I doing wrong? BONUS When I do get this working correctly, is the ENTIRE CLASS passed with the serialized object (i.e. will I have access to the methods of the object's class)? My reading suggests that the entire class is passed with the object, but I have been unable to use the objects methods thus far. How exactly do I call on the object's methods? In addition to my code above I also experimented with the readObject method, but I was probably using it wrong too because I couldn't get it to work. Please enlighten me.

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• Avoiding Object Oriented Pitfalls, Migrating from C, What Worked for You?

  - by Stephen

  I've been programming in procedural languages for quite some time now, and my first reaction to a problem is to start breaking it down into tasks to perform rather than to consider the different entities (objects) that exist and their relationships. I have had a university course in OOP, and understand the fundamentals of encapsulation, data abstraction, polymorphism, modularity and inheritance. I read Learning to think in the Object Oriented Way and Learning object oriented thinking, and will be looking at some of the books pointed to in those answers. I think that several of my medium to large sized projects will benefit from effective use of OOP but as a novice I would like to avoid time consuming, common errors. Based on your experiences, what are these pitfalls and what are reasonable ways around them? If you could explain why they are pitfalls, and how your suggestion is effective in addressing the issue it'd be appreciated. I'm thinking along the lines of something like "Is it common to have a fair number of observer and modifier methods and use private variables or are there techniques for consolidating/reducing them?" I'm not worried about using C++ as a pure OO language, if there are good reasons to mix methods. (Reminiscent of the reasons to use GOTOs, albeit sparingly.) Thank you!

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• DB Object passing between classes singleton, static or other?

  - by Stephen

  So I'm designing a reporting system at work it's my first project written OOP and I'm stuck on the design choice for the DB class. Obviously I only want to create one instance of the DB class per-session/user and then pass it to each of the classes that need it. What I don't know it what's best practice for implementing this. Currently I have code like the following:- class db { private $user = 'USER'; private $pass = 'PASS'; private $tables = array( 'user','report', 'etc...'); function __construct(){ //SET UP CONNECTION AND TABLES } }; class report{ function __construct ($params = array(), $db, $user) { //Error checking/handling trimed //$db is the database object we created $this->db = $db; //$this->user is the user object for the logged in user $this->user = $user; $this->reportCreate(); } public function setPermission($permissionId = 1) { //Note the $this->db is this the best practise solution? $this->db->permission->find($permissionId) //Note the $this->user is this the best practise solution? $this->user->checkPermission(1) $data=array(); $this->db->reportpermission->insert($data) } };//end report I've been reading about using static classes and have just come across Singletons (though these appear to be passé already?) so what's current best practice for doing this?

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• Blob object not working properly even though the class is seralized

  - by GustlyWind

  I have class which is seralized and does convert a very large amount of data object to blob to save it to database.In the same class there is decode method to convert blob to the actual object.Following is the code for encode and decode of the object. private byte[] encode(ScheduledReport schedSTDReport) { byte[] bytes = null; try { ByteArrayOutputStream bos = new ByteArrayOutputStream(); ObjectOutputStream oos = new ObjectOutputStream(bos); oos.writeObject(schedSTDReport); oos.flush(); oos.close(); bos.close(); //byte [] data = bos.toByteArray(); //ByteArrayOutputStream baos = new ByteArrayOutputStream(); //GZIPOutputStream out = new GZIPOutputStream(baos); //XMLEncoder encoder = new XMLEncoder(out); //encoder.writeObject(schedSTDReport); //encoder.close(); bytes = bos.toByteArray(); //GZIPOutputStream out = new GZIPOutputStream(bos); //out.write(bytes); //bytes = bos.toByteArray(); } catch (Exception e) { _log.error("Exception caught while encoding/zipping Scheduled STDReport", e); } decode(bytes); return bytes; } /* * Decode the report definition blob back to the * ScheduledReport object. */ private ScheduledReport decode(byte[] bytes) { ByteArrayInputStream bais = new ByteArrayInputStream(bytes); ScheduledReport sSTDR = null; try { ObjectInputStream ois = new ObjectInputStream(bais); //GZIPInputStream in = new GZIPInputStream(bais); //XMLDecoder decoder = new XMLDecoder(in); sSTDR = (ScheduledReport)ois.readObject();//decoder.readObject(); //decoder.close(); } catch (Exception e) { _log.error("IOException caught while decoding/unzipping Scheduled STDReport", e); } return sSTDR; } The problem here is whenver I change something else in this class means any other method,a new class version is created and so the new version the class is unable to decode the originally encoded blob object. The object which I am passing for encode is also seralized object but this problem exists. Any ideas thanks

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• Xna model parts are overlying others

  - by Federico Chiaravalli

  I am trying to import in XNA an .fbx model exported with blender. Here is my drawing code public void Draw() { Matrix[] modelTransforms = new Matrix[Model.Bones.Count]; Model.CopyAbsoluteBoneTransformsTo(modelTransforms); foreach (ModelMesh mesh in Model.Meshes) { foreach (BasicEffect be in mesh.Effects) { be.EnableDefaultLighting(); be.World = modelTransforms[mesh.ParentBone.Index] * GameCamera.World * Translation; be.View = GameCamera.View; be.Projection = GameCamera.Projection; } mesh.Draw(); } } The problem is that when I start the game some model parts are overlying others instead of being behind. I've tried to download other models from internet but they have the same problem.

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• Encapsulate update method inside of object or have method which accepts an object to update

  - by Tom

  Hi, I actually have 2 questions related to each other: I have an object (class) called, say MyClass which holds data from my database. Currently I have a list of these objects ( List < MyClass ) that resides in a singleton in a "communal area". I feel it's easier to manage the data this way and I fail to see how passing a class around from object to object is beneficial over a singleton (I would be happy if someone can tell me why). Anyway, the data may change in the database from outside my program and so I have to update the data every so often. To update the list of the MyClass I have a method called say, Update, written in another class which accepts a list of MyClass. This updates all the instances of MyClass in the list. However would it be better instead to encapulate the Update() method inside the MyClass object, so instead I would say foreach(MyClass obj in MyClassList) { obj.update(); } What is a better implementation and why? The update method requires a XML reader. I have written an XML reader class which is basically a wrapper over the standard XML reader the language natively provides which provides application specific data collection. Should the XML reader class be in anyway in the "inheritance path" of the MyClass object - the MyClass objects inherits from the XML reader because it uses a few methods. I can't see why it should. I don't like the idea of declaring an instance of the XML Reader class inside of MyClass and an MyClass object is meant to be a simple "record" from the database and I feel giving it loads of methods, other object instances is a bit messy. Perhaps my XML reader class should be static but C#'s native XMLReader isn't static.? Any comments would be greatly appreciated Thanks Thomas

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• DTO or Domain Model Object in the View Layer?

  - by smayers81

  I know this is probably an age-old question, but what is the better practice? Using a domain model object throughout all layers of your application, and even binding values directly to them on the JSP (I'm using JSF). Or convert a domain model object into a DTO in the DAO or Service layer and send a lightweight DTO to the presentation layer. I have been told it makes no sense to use DTOs because changes to the database will result in changes to all your DTOs whereas using Model Objects everywhere will just require changes to the affected model object. However, the ease of use and the lightweight nature of DTOs seems to outweigh that. I should note that my app uses Hibernate Model Objects AND uses its own custom-created model objects (meaning not bound to any DB session, always detached). Is either of the above scenarios more beneficial to a strict Model Object pattern? Using Hibernate has been a huge PITA with regards to things like Lazy Initialization Exceptions.

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• search through related field for specific related object

  - by dotty

  Hay, I'm working on a simple voting system, where users can vote on a poll. My model looks like this class Poll(models.Model): question = models.CharField() votes = models.IntegerField() usersVoted = models.ManyToManyField(User) Now, i want to scan through the usersVoted field to see if a User object is in there. This User object will then be matched against a logged in User (User obj saved in a session). If the User has voted i want to be able to set a 'has_voted' field. I then want to use this field in my view. I will be using the Property() thingy inside the model to work this 'has_voted' value out. Like so def _can_vote(self): return False can_vote = property(_can_vote) Obviously it'll return a Bool. Any ideas how to search through a related field to find a specific Object?

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• changing the saved contents of the model , edit model fileds once saved

  - by imran-glt

  hi I have extended the user model and added extra fields to it i.e "latitude" "longitude" and status and than save it. up to here it works fine. but i want to allow the user to change his/her "latitude" "longitude" whenever he/she needs like the hotmail and yahoo allows change account feature. in my case the user only wants to chage the latitude and longitude i tried it in this way but it didnt work. is this the right way to do it ...... or is there any other way to change the saved contents view.py def status_change(request): print "status_change function called" if request.method == "POST": rform = registerForm(data = request.POST) uform = UserForm(data = request.POST) if rform.is_valid(): user = uform.save() register = rform.save() register.user = user register.save() return render_to_response('home.html') else: rform = registerForm() return render_to_response('status_change.html',{'rform':rform})

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