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  • DB Schema for ACL involving 3 subdomains

    - by blacktie24
    Hi, I am trying to design a database schema for a web app which has 3 subdomains: a) internal employees b) clients c) contractors. The users will be able to communicate with each other to some degree, and there may be some resources that overlap between them. Any thoughts about this schema? Really appreciate your time and thoughts on this. Cheers! -- -- Table structure for table locations CREATE TABLE IF NOT EXISTS locations ( id bigint(20) NOT NULL, name varchar(250) NOT NULL ) ENGINE=InnoDB DEFAULT CHARSET=latin1; -- -- Table structure for table privileges CREATE TABLE IF NOT EXISTS privileges ( id int(11) NOT NULL AUTO_INCREMENT, name varchar(255) NOT NULL, resource_id int(11) NOT NULL, PRIMARY KEY (id) ) ENGINE=InnoDB DEFAULT CHARSET=latin1 AUTO_INCREMENT=10 ; -- -- Table structure for table resources CREATE TABLE IF NOT EXISTS resources ( id int(11) NOT NULL AUTO_INCREMENT, name varchar(255) NOT NULL, user_type enum('internal','client','expert') NOT NULL, PRIMARY KEY (id) ) ENGINE=InnoDB DEFAULT CHARSET=latin1 AUTO_INCREMENT=3 ; -- -- Table structure for table roles CREATE TABLE IF NOT EXISTS roles ( id int(11) NOT NULL AUTO_INCREMENT, name varchar(255) NOT NULL, type enum('position','department') NOT NULL, parent_id int(11) DEFAULT NULL, user_type enum('internal','client','expert') NOT NULL, PRIMARY KEY (id) ) ENGINE=InnoDB DEFAULT CHARSET=latin1 AUTO_INCREMENT=3 ; -- -- Table structure for table role_perms CREATE TABLE IF NOT EXISTS role_perms ( id int(11) NOT NULL AUTO_INCREMENT, role_id int(11) NOT NULL, privilege_id int(11) NOT NULL, mode varchar(250) NOT NULL, PRIMARY KEY (id) ) ENGINE=InnoDB DEFAULT CHARSET=latin1 AUTO_INCREMENT=2 ; -- -- Table structure for table users CREATE TABLE IF NOT EXISTS users ( id int(10) unsigned NOT NULL AUTO_INCREMENT, email varchar(255) NOT NULL, password varchar(255) NOT NULL, salt varchar(255) NOT NULL, type enum('internal','client','expert') NOT NULL, first_name varchar(255) NOT NULL, last_name varchar(255) NOT NULL, location_id int(11) NOT NULL, phone varchar(255) NOT NULL, status enum('active','inactive') NOT NULL DEFAULT 'active', PRIMARY KEY (id) ) ENGINE=InnoDB DEFAULT CHARSET=latin1 AUTO_INCREMENT=4 ; -- -- Table structure for table user_perms CREATE TABLE IF NOT EXISTS user_perms ( id int(11) NOT NULL AUTO_INCREMENT, user_id int(11) NOT NULL, privilege_id int(11) NOT NULL, mode varchar(250) NOT NULL, PRIMARY KEY (id) ) ENGINE=InnoDB DEFAULT CHARSET=latin1 AUTO_INCREMENT=2 ; -- -- Table structure for table user_roles CREATE TABLE IF NOT EXISTS user_roles ( id int(11) NOT NULL, user_id int(11) NOT NULL, role_id int(11) NOT NULL ) ENGINE=InnoDB DEFAULT CHARSET=latin1;

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  • Metaobject protocol:Why is it known as an important concept

    - by sushant
    Metaobject protocol is protocol for metaobjects in a programming languages. Although I understand it on simple terms, I want to know the reason and a summary of real world usage patterns of this protocol. So, why exactly is metaobject and more importantly metaobject protocol is such a good idea. I want to know the problem which led to its evolution and also, its high power usage. Opinions as well as general overview/description/alternate explanations are also welcome.

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  • design for supporting entities with images

    - by brainydexter
    I have multiple entities like Hotels, Destination Cities etc which can contain images. The way I have my system setup right now is, I think of all the images belonging to this universal set (a table in the DB contains filePaths to all the images). When I have to add an image to an entity, I see if the entity exists in this universal set of images. If it exists, attach the reference to this image, else create a new image. E.g.: class ImageEntityHibernateDAO { public void addImageToEntity(IContainImage entity, String filePath, String title, String altText) { ImageEntity image = this.getImage(filePath); if (image == null) image = new ImageEntity(filePath, title, altText); getSession().beginTransaction(); entity.getImages().add(image); getSession().getTransaction().commit(); } } My question is: Earlier I had to write this code for each entity (and each entity would have a Set collection). So, instead of re-writing the same code, I created the following interface: public interface IContainImage { Set<ImageEntity> getImages(); } Entities which have image collections also implements IContainImage interface. Now, for any entity that needs to support adding Image functionality, all I have to invoke from the DAO looks something like this: // in DestinationDAO::addImageToDestination { imageDao.addImageToEntity(destination, imageFileName, imageTitle, imageAltText); // in HotelDAO::addImageToHotel { imageDao.addImageToEntity(hotel, imageFileName, imageTitle, imageAltText); It'd be great help if someone can provide me some critique on this design ? Are there any serious flaws that I'm not seeing right away ?

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  • Is there a good design pattern for this messaging class?

    - by salonMonsters
    Is there a good design pattern for this? I want to create a messaging class. The class will be passed: the type of message (eg. signup, signup confirmation, password reminder etc) the client's id The class needs to then look up the client's messaging preferences in the db (whether they want communication by email, sms or both) Then depending on the client's preference it will format the message for the medium (short version for sms, long form for email) and send it through our mail or sms provider's API. Because the fact that we want to be able to change out email and sms providers if need be I wondered if the Command Pattern would be a good choice.

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  • Design pattern to handle queries using multiple models

    - by coderkane
    I am presented with a dilemma while trying to re-designing the class structure for my PHP/MySQL application to make it more elegant and conform it to the SOLID principle. The problem goes like this: Let as assume, there is an abstract class called person which has certain properties to define a generic person, such as name, age, date of birth etc. There are two classes, student, and teacher, that implements this abstract class. They add their own unique properties to it. I have designed all the three classes to include all the operational logic (details of which are not relevant in context of the question). Now, I need to create views/reports/data grids which contain details from multiple classes, for example, say, a list of all students doing projects in Chemistry mentored by a teacher whose name is the parameter to the query. This is just one example of a view, there are many different views in the application, which uses data from 3-4 tables, and each of them have multiple input parameters to generate them. Considering this particular example, I have written the relevant query using JOIN and the results are as expected and proper, now here is the dilemma: Keeping in mind the single responsibility principle, where should I keep this query? It does not belong to either Student class, or Teacher class or any other classes currently present. a) Should I create a new class, say dataView class, and design it as a MVC pattern and keep the query there? What about the other views? how do they fit in this architecture? b) Should I not keep the query in code at all, and make it DB View ? c) Am I completely wrong in the approach? If so what is the right approach? My considerations are as follows: a) should be easy to add new views later on if requirement comes, without having to copy-paste-modify code b) would like to make it as loosely coupled as possible so that if minor db structure changes happen, it does not break I did google searches on report design and OOP report generators, but all the result seem to focus on the visual design of the report rather than fetching the data. I have already taken care of the visual aspect of the report using MVC with html templates. I am sure this is a very fundamental problem with known solution, but I am somehow not able to find it (maybe searching with wrong keyword). Edit1: Modified the title to make it more relevant Edit2: The accepted answer got me thinking in the right direction and identify my design flaws, which eventually led me to find this question and the solution in Stack Overflow which gave me the detailed answer to clear the confusion.

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  • Trying to find a recent - PHP book - that utilizes SOLID principles! [closed]

    - by darga33
    Pulling my hair out! I have heard of Martin Fowler's book PoEAA and the other book Head First OOA OOD but those are not in PHP. I desperately want to read them, but ONLY in PHP utilizing the - SOLID acronym - principles! Does anyone know of the absolute best, most recent PHP book that utilizes the SOLID principles and GRASP, and all the other best practices? I want to learn from the best possible source! Not beginner books! I already understand OOP. This seems like an almost impossible question to find the answer to and so I thought, hey, might as well post on stackexchange!! Surely someone out there must know!!!!!!!!!! Or if noone happens to know, Maybe they know of an open source application that utilizes these principles that is relatively small that is not a framework. Something that I can go through every single class, and spend time understanding the insides and outs of how the program was developed. Thanks so much in advance! I really really really really appreciate it! Well it looks like we aren't supposed to ask about best books, so nevermind this question! Sorry about that!

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  • Why should a class be anything other than "abstract" or "final/sealed"

    - by Nicolas Repiquet
    After 10+ years of java/c# programming, I find myself creating either: abstract classes: contract not meant to be instantiated as-is. final/sealed classes: implementation not meant to serve as base class to something else. I can't think of any situation where a simple "class" (i.e. neither abstract nor final/sealed) would be "wise programming". Why should a class be anything other than "abstract" or "final/sealed" ? EDIT This great article explains my concerns far better than I can.

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  • Learning good OOP design & unlearning some bad habits

    - by Nick
    I have been mostly a C programmer so far in my career with knowledge of C++. I rely on C++ mostly for the convenience STL provides and I hardly ever focus on good design practices. As I have started to look for a new job position, this bad habit of mine has come back to haunt me. During the interviews, I have been asked to design a problem (like chess, or some other scenario) using OOP and I doing really badly at that (I came to know this through feedback from one interview). I tried to google stuff and came up with so many opinions and related books that I don't know where to begin. I need a good through introduction to OOP design with which I can learn practical design, not just theory. Can you point me to any book which meets my requirements ? I prefer C++, but any other language is fine as long as I can pick-up good practices. Also, I know that books can only go so far. I would also appreciate any good practice project ideas that helped you learn and improve your OOP concepts. Thanks.

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  • Procedural object generation and unique identification

    - by 2080
    My question relates to procedural content generation and data management of the emerging objects in a database. I assume a networked game, with a server-client model. Unspecified objects in the game world are generated while the game is running with procedural algorithms (for example perlin noise). The players (/clients) can modify the properties of these objects, but have to notify the server of these changes. How could this communication address unique objects, so that both the server and the client know of which object they are speaking? Not only the inner properties of the objects can differ, but also visible, such as the position. When the player wants to select one of these objects the game has to find out the id - does anyone know which methods or algorithms can accomplish that?

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  • Law of Demeter confusion [duplicate]

    - by user2158382
    This question already has an answer here: Rails: Law of Demeter Confusion 4 answers I am reading a book called Rails AntiPatterns and they talk about using delegation to to avoid breaking the Law of Demeter. Here is their prime example: They believe that calling something like this in the controller is bad (and I agree) @street = @invoice.customer.address.street Their proposed solution is to do the following: class Customer has_one :address belongs_to :invoice def street address.street end end class Invoice has_one :customer def customer_street customer.street end end @street = @invoice.customer_street They are stating that since you only use one dot, you are not breaking the Law of Demeter here. I think this is incorrect, because you are still going through customer to go through address to get the invoice's street. I primarily got this idea from a blog post I read: http://www.dan-manges.com/blog/37 In the blog post the prime example is class Wallet attr_accessor :cash end class Customer has_one :wallet # attribute delegation def cash @wallet.cash end end class Paperboy def collect_money(customer, due_amount) if customer.cash < due_ammount raise InsufficientFundsError else customer.cash -= due_amount @collected_amount += due_amount end end end The blog post states that although there is only one dot customer.cash instead of customer.wallet.cash, this code still violates the Law of Demeter. Now in the Paperboy collect_money method, we don't have two dots, we just have one in "customer.cash". Has this delegation solved our problem? Not at all. If we look at the behavior, a paperboy is still reaching directly into a customer's wallet to get cash out. Can somebody help me clear the confusion. I have been searching for the past 2 days trying to let this topic sink in, but it is still confusing.

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  • How to verify the Liskov substitution principle in an inheritance hierarchy?

    - by Songo
    Inspired by this answer: Liskov Substitution Principle requires that Preconditions cannot be strengthened in a subtype. Postconditions cannot be weakened in a subtype. Invariants of the supertype must be preserved in a subtype. History constraint (the "history rule"). Objects are regarded as being modifiable only through their methods (encapsulation). Since subtypes may introduce methods that are not present in the supertype, the introduction of these methods may allow state changes in the subtype that are not permissible in the supertype. The history constraint prohibits this. I was hoping if someone would post a class hierarchy that violates these 4 points and how to solve them accordingly. I'm looking for an elaborate explanation for educational purposes on how to identify each of the 4 points in the hierarchy and the best way to fix it. Note: I was hoping to post a code sample for people to work on, but the question itself is about how to identify the faulty hierarchies :)

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  • Is loose coupling w/o use cases an anti-pattern?

    - by dsimcha
    Loose coupling is, to some developers, the holy grail of well-engineered software. It's certainly a good thing when it makes code more flexible in the face of changes that are likely to occur in the foreseeable future, or avoids code duplication. On the other hand, efforts to loosely couple components increase the amount of indirection in a program, thus increasing its complexity, often making it more difficult to understand and often making it less efficient. Do you consider a focus on loose coupling without any use cases for the loose coupling (such as avoiding code duplication or planning for changes that are likely to occur in the foreseeable future) to be an anti-pattern? Can loose coupling fall under the umbrella of YAGNI?

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  • How to improve programming skills?

    - by Mike
    I'm very new to programming. I started learning PHP about half a year ago, so I do know something. I can write small functions, I can export and import information from a database and I can make a website. I don't know OOP principles and I don't know about objects and classes. Should I move to OOP principles and learn about classes, methods and objects? If not, what should I do? Continue writing simple code? How can a programmer write his/her own API? Is OOP necessary to do this? So how can i improve my skills? I love programming. I spend my 24/7 on it, so any help will be appreciated.

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  • Render 3d object to 2d surface (embedded system)

    - by Martin Berger
    i am working on an embedded system of a sort, and in some free time i would like to test its drawing capabilities. System in question is ARM Cortex M3 microcontroller attached to EasyMX Stellaris board. And i have a small 320x240 TFT screen :) Now, i have some free time each day and i want to create rotating cube. Micro C PRO for ARM doesnt have 3d drawing capabilities, which means it must be done in software. From the book Introduction to 3D Game Programming with DirectX 10 i know matrix algebra for transformations but that is cool when you have DirectX to set camera right. I gues i could make 2d object to rotate, but how would i go with 3d one? Any ideas and examples are welcome. Although i would prefer advices. I'd like to understand this.

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  • OOP private method parameters coding style

    - by Jake
    After coding for many years as a solo programmer, I have come to feel that most of the time there are many benefits to write private member functions with all of the used member variables included in the parameter list, especially development stage. This allow me to check at one look what member variables are used and also allow me to supply other values for tests and debugging. Also, a change in code by removing a particular member variable can break many functions. In this case however, the private function remains isolated am I can still call it using other values without fixing the function. Is this a bad idea afterall, especially in a team environment? Is it like redundant or confusing, or are there better ways?

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  • To identify the classes for uml diagrams?

    - by user106535
    I want to implement a software engineering project based on "crime management system". The main modules are: visitors, users, administrator. The main events that are taking place are: registration, report complaint, report crime, report most wanted, view status of reported crime. So could you please help me to identify the classes that are to be used in this project and help me to draw the class diagram?

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  • Where can I learn about every OOP concept?

    - by Mel
    I'm looking for some material that can explain all the concepts related to OOP that doesn't deviate too much from the point. I want something short and understandable for a beginner. I know some of these can be found on wikipedia, but wikipedia is full of minor and sometimes big mistakes and I don't think that is the best choice for learning something. Where should I start ? Also, please don't recommend books of 1000 pages or such.

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  • Dependency Injection: Only for single-instance objects?

    - by HappyDeveloper
    What if I want to also decouple my application, from classes like Product or User? (which usually have more than one instance) Take a look at this example: class Controller { public function someAction() { $product_1 = new Product(); $product_2 = new Product(); // do something with the products } } Is it right to say that Controller now depends on Product? I was thinking that we could decouple them too (as we would with single-instance objects like Database) In this example, however ugly, they are decoupled: class Controller { public function someAction(ProductInterface $new_product) { $product_1 = clone $new_product; $product_2 = clone $new_product; // do something with the products } } Has anyone done something like this before? Is it excessive?

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  • how should I design Objects around this business requirement?

    - by brainydexter
    This is the business requirement: " A Holiday Package (e.g. New York NY Holiday Package) can be offered in different ways based on the Origin city: From New Delhi to NY From Bombay to NY NY itself ( Land package ) (Bold implies default selection) a. and b. User can fly from either New Delhi or Bombay to NY. c. NY is a Land package, where a user can reach NY by himself and is a standalone holidayPackage. " Let's say I have a class that represents HolidayPackage, Destination (aka City). public class HolidayPackage{ Destination holidayCity; ArrayList<BaseHolidayPackageVariant> variants; BaseHolidayPackageVariant defaultVariant; } public abstract class BaseHolidayPackageVariant { private Integer variantId; private HolidayPackage holidayPackage; private String holidayPackageType; } public class LandHolidayPackageVariant extends BaseHolidayPackageVariant{ } public class FlightHolidayPackageVariant extends BaseHolidayPackageVariant{ private Destination originCity; } What data structure/objects should I design to support: options a default within those options Sidenote: A HolidayPackage can also be offered in different ways based on Hotel selections. I'd like to follow a design which I can leverage to support that use case in the future. This is the backend design I have in mind.

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  • Fetching database query through function

    - by Shubham Maurya
    I am sick of connecting database in each script i need a more OOP approach to fetching database results. ex like wordpress use wpdb class to fetch results. This what wordpress does to get data <?php $posts = $wpdb->get_results("SELECT ID, post_title FROM $wpdb->posts WHERE post_status = 'publish' AND post_type='post' ORDER BY comment_count DESC LIMIT 0,4") ?> How can i create the same feature too using any class or function and use it in my script Thank you

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  • Designing a "Grid" like object that contains game objects

    - by liortal
    I am working on a 2D game, where there's a game "board" on which other game objects are placed. This this is 2D, my starting point was to design a class that will internally use a 2d array for the actual stored game objects. This class could be simply accessed by 2 indices: (i, j) to get game objects on it. My problem is that i have no idea how to make the game "board" "propagate" its data onto its children. Design questions i ran into are: Should the children placed on the board have display properties such as size, screen position? Should the board itself dictate this information? How to update children in case the board changes some of its properties? (position, etc). Should the board be aware of the types of objects stored in it ? I have no idea how similar things such as WPF or other UI frameworks go about organizing a "container like" object that can arrange or apply certain UI properties to its children.

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  • Ruby - when to use instance variables vs parameters between methods?

    - by Michael Durrant
    I'm writing several methods that call other methods. To pass the information I have a couple of choices: Pass the information as parameters Set instance variables so that other methods can access them When should I choose one option over the other? It seems that the first option is good as it is very specific about what is being passed. the downside seems to be that a lot of values are being passed around. The second method doesn't require passing all the values around but seems to lead to a lot of magic where methods set instance variables 'somewhere' Should I always be very explicit about gets passed to other methods in the class? Are there exceptions so this?

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  • Is having 'Util' classes a cause for concern? [closed]

    - by Matt Fenwick
    I sometimes create 'Util' classes which primarily serve to hold methods and values that don't really seem to belong elsewhere. But every time I create one of these classes, I think "uh-oh, I'm gonna regret this later ...", because I read somewhere that it's bad. But on the other hand, there seem to be two compelling (at least for me) cases for them: implementation secrets that are used in multiple classes within a package providing useful functionality to augment a class, without cluttering its interface Am I on the way to destruction? What you say !! Should I refactor?

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  • Breaking up classes and methods into smaller units

    - by micahhoover
    During code reviews a couple devs have recommended I break up my methods into smaller methods. Their justification was (1) increased readability and (2) the back trace that comes back from production showing the method name is more specific to the line of code that failed. There may have also been some colorful words about functional programming. Additionally I think I may have failed an interview a while back because I didn't give an acceptable answer about when to break things up. My inclination is that when I see a bunch of methods in a class or across a bunch of files, it isn't clear to me how they flow together, and how many times each one gets called. I don't really have a good feel for the linearity of it as quickly just by eye-balling it. The other thing is a lot of people seem to place a premium of organization over content (e.g. 'Look at how organized my sock drawer is!' Me: 'Overall, I think I can get to my socks faster if you count the time it took to organize them'). Our business requirements are not very stable. I'm afraid that if the classes/methods are very granular it will take longer to refactor to requirement changes. I'm not sure how much of a factor this should be. Anyway, computer science is part art / part science, but I'm not sure how much this applies to this issue.

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  • Setting up ASP.NET structure for code

    - by user1175327
    I've always coded in C# MVC3 when developing web applications. But now i wanted to learn a bit more about developing web sites with just ASP.NET. But now i'm wondering what a good setup for my code would be. For me, an MVC like pattern seems to be a good way to go. But obviously ASP.NET doesn't have any router and controller classes. So i guess people have a different way of setting up their code when they do ASP.NET. So i'm looking for more information on how to get started with this. So not really the basics of ASP.NET, but something that focuses on a good code setup. Any good tutorials/information about this/?

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