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  • Dynamic swappable Data Access Layer

    - by Andy
    I'm writing a data driven WPF client. The client will typically pull data from a WCF service, which queries a SQL db, but I'd like the option to pull the data directly from SQL or other arbitrary data sources. I've come up with this design and would like to hear your opinion on whether it is the best design. First, we have some data object we'd like to extract from SQL. // The Data Object with a single property public class Customer { private string m_Name = string.Empty; public string Name { get { return m_Name; } set { m_Name = value;} } } Then I plan on using an interface which all data access layers should implement. Suppose one could also use an abstract class. Thoughts? // The interface with a single method interface ICustomerFacade { List<Customer> GetAll(); } One can create a SQL implementation. // Sql Implementation public class SqlCustomrFacade : ICustomerFacade { public List<Customer> GetAll() { // Query SQL db and return something useful // ... return new List<Customer>(); } } We can also create a WCF implementation. The problem with WCF is is that it doesn't use the same data object. It creates its own local version, so we would have to copy the details over somehow. I suppose one could use reflection to copy the values of similar fields across. Thoughts? // Wcf Implementation public class WcfCustomrFacade : ICustomerFacade { public List<Customer> GetAll() { // Get date from the Wcf Service (not defined here) List<WcfService.Customer> wcfCustomers = wcfService.GetAllCustomers(); // The list we're going to return List<Customer> customers = new List<Customer>(); // This is horrible foreach(WcfService.Customer wcfCustomer in wcfCustomers) { Customer customer = new Customer(); customer.Name = wcfCustomer.Name; customers.Add(customer); } return customers; } } I also plan on using a factory to decide which facade to use. // Factory pattern public class FacadeFactory() { public static ICustomerFacade CreateCustomerFacade() { // Determine the facade to use if (ConfigurationManager.AppSettings["DAL"] == "Sql") return new SqlCustomrFacade(); else return new WcfCustomrFacade(); } } This is how the DAL would typically be used. // Test application public class MyApp { public static void Main() { ICustomerFacade cf = FacadeFactory.CreateCustomerFacade(); cf.GetAll(); } } I appreciate your thoughts and time.

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  • How to define schema for an ActiveRecord model?

    - by Eric Stanton
    I can find how to define columns only when doing migrations. However i do not need to migrate my model. I want to work with it "virtually". Does AR read columns data only from db? Any way to define columns like in DataMapper? class Post include DataMapper::Resource property :id, Serial property :title, String property :published, Boolean end Now i can play with my model without migrations/connections.

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  • I have a feeling that adding fields marked with @Transient annotation to entity is very bug-prone. A

    - by Roman
    I have some philosophical feeling that adding to an entity fields which doesn't mapped to the DB is a wrong way of solving problems. But are there any concrete situations where using @Transient fields leads to implicit and hard fixing problems? For example, is it possible that adding/removing 2nd level cache will break our app when there are @Transient fields in our entities?

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  • Drawbacks of using an integer as a bitfield?

    - by Mark
    I have a bunch of boolean options for things like "accepted payment types" which can include things like cash, credit card, cheque, paypal, etc. Rather than having a half dozen booleans in my DB, I can just use an integer and assign each payment method an integer, like so PAYMENT_METHODS = ( (1<<0, 'Cash'), (1<<1, 'Credit Card'), (1<<2, 'Cheque'), (1<<3, 'Other'), ) and then query the specific bit in python to retrieve the flag. I know this means the database can't index by specific flags, but are there any other drawbacks?

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  • PropertyChanged Event of ObservableCollection

    - by developer
    Hi All, I have a observable collection of viewmodel objects. How can I subscribe to the Property Changed event of each view model in my collection as they are created and track which ones have been changed, so that I can updated them to my database. List<DomainObject> objectsToSave = new List<DomainObject>(); foreach (Test val in dirtyObjs) { objectsToSave.AddRange(val.GetObjectsToSave()); } //DB changes bool saveSucceeded = DataServices.SaveMultiple(objectsToSave);

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  • Win2k3 password Authentication using LDAP in VC++

    - by user001
    Hi, I need to implement the Win2k3 password validation policy. As my application resides on Win2k3 cane we validate the password directly with windows domain password by using LDAP. This is because application design does not want to store 8/more password entry into DB and validate new password against that. As Windows already does same thing and using LDAP we can lookup into windows server. Can any one please let me know LDAP API to fulfill above requirement in VC++.

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  • Convert a form_tag select_datetime to SQL datetime

    - by Mitchell
    Hi I am trying to make a simple search form that uses a startTime and endTime to specify a time range. The db has a datetime field time that is compared against. So far when i try to use params[:startTime] in the controller I get an array of values which wont work with :conditions = ['time < ?', params[:endTime]] Is there a simple solution to parse the form's datetime to SQL datetime?

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  • How can I build a voting system to support multiple types of objects to vote on?

    - by Kyle Hayes
    I'm really looking for something very similar to the way SO is setup where a few different kinds of things can be voted on (questions AND answers). What kind of DB schema, generally, could I use to support voting on many different kinds of objects? Would I have a single Vote table that would have references to other objects in the database? Or do I have to have or should have a separate vote table for each of the objects I would like to vote on.

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  • Need to split a string into two parts in java

    - by Reddy
    I have a string which contains a contiguous chunk of digits and then a contiguous chunk of characters. I need to split them into two parts (one integer part, and one string). I tried using String.split("\D", 1), but it is eating up first character. I checked all the String API and didn't find a suitable method. Is there any method for doing this thing?

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  • Recipe for creating a corrupt mysql table

    - by Chaim Geretz
    We had a process that crashed while trying to manipulate an expected mysql record set, running the offending query from the mysql cli showed the following. mysql SELECT ...; ERROR 1030: Got error 127 from table handler Is there a way to easily recreate this condition so we can validate our fix ? (production DB was already repaired).

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  • what does a tool like Jasper Reports give me?

    - by Itay Moav
    Ok, So I have to generate very complex reports from my DB. If I am to do it with SQL the query themselves will be complex, and I will have to do some more manipulation on the results later, code level. How do libraries like Jasper Reports/ Crystal Reports and friends save me time when developing such reports? What will they give me?

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  • Moving .JS files to a CDN: How to manage AJAX requests?

    - by pagewil
    I am thinking of moving my static .JS files to a CDN such as Amazon S3 for performance reasons. As my PHP files and mySQL DB remain on my primary hosting domain what is the best way to manage my JS AJAX requests if they are now cross domain? Currently they look like this within my .JS file (with relative paths): $.ajax({ type: "POST", url: "/myNearbyPhpFile.php", data: {data:someData}, success: function($r){} });

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  • SQLAlchemy: an efficient/better select by primary keys?

    - by hadrien
    Yet another newbie question.. Let's say I have an user table in declarative mode: class User(Base): __tablename__ = 'user' id = Column(u'id', Integer(), primary_key=True) name = Column(u'name', String(50)) When I have a list of users identifiers, I fetch them from db with: user_ids = [1, 2, 3, 4, 5] users = Session.query(User).filter(User.id.in_(user_ids)).all() I dislike using in_ because I think I learned it has bad performance on indexed fields (is that true/false?). Anyway, is there a better way doing that query? Thanks!

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  • codeigniter - pass all form values to model

    - by Patrick
    I have a registration form that collects several parameters. i need to pass all these AND a confirmation code (generated by the controller) to the model for inserting in the DB. How can I do that? is there a way to pass the whole post to the model, eg like $this->model->insert($this->input->form(), $confirmation_code)?

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