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BlayerContext class

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Eros Stein edited this page Jan 13, 2017 · 2 revisions

Constructor

BlayerContext(RepositoryConfiguration config, params IRepository[] repositories)

  • Creates a new context using repositories from the informed configuration. If repositories is informed, they are concatenated into the config ones.
  • Parameters:
    • RepositoryConfiguration config - Repository configuration
    • IRepository[] repositories - Extra repositories to be loaded

Usage:

Repository configuration class:

public class AppConfiguration : RepositoryConfiguration
{
    public StateRepository StateRepository;
    public CountryRepository CountryRepository;
    public CityRepository CityRepository;
}

Business logic layer:

using (var ctx = new AppContext(new AppConfiguration()))
{
    return ctx.GetRepository<Country>().GetAll();
}

Using extra repositories:

using (var ctx = new AppContext(new AppConfiguration(), new DistrictRepository()))
{
    return ctx.GetRepository<District>().GetAll();
}

GetRepository

IRepository<T> GetRepository<T>()

  • Retrieves a repository representing the database entity of the informed type.
  • Type parameter:
    • T : EntityBase - Repository base class type

Usage:

using (var ctx = new AppContext(new AppConfiguration()))
{
    var countryRepository = ctx.GetRepository<Country>();
    return countryRepository.GetAll();
}

TReturn GetRepository<T, TReturn>()

  • Retrieves a repository casting to a specific type. Using it this way we're able to use repository specific methods.
  • Type parameters:
    • T : EntityBase - Repository base class type (your POCO class)
    • TReturn : Repository<T> - Repository type

Usage:

Repository class:

public class CountryRepository : Repository<Country>
{
    public Country GetByCountryCode(string countryCode)
    {
        return GetAll().FirstOrDefault(c => c.CountryCode == countryCode);
    }
}

Usage:

using (var ctx = new AppContext(new AppConfiguration()))
{
    return ctx.GetRepository<Country, CountryRepository>()
              .GetByCountryCode("USA"); // repository specific method
}

CRUD operations

T Add<T>(T entity)

  • Adds a new entity to the context with the provided data
  • Type parameter:
    • T : EntityBase - Type of the entity
  • Parameters:
    • T entity - Entity's data

Usage:

using (var ctx = new AppContext(new AppConfiguration()))
{
    var account = ctx.Add(new Account
    {
        CreationDate = DateTime.Now,
        Name = "Super account"
    });

    ctx.Save();
}

T Add<T>()

  • Adds a new, empty entity to the context
  • Type parameter:
    • T : EntityBase - Type of the entity

Usage:

using (var ctx = new AppContext(new AppConfiguration()))
{
    var account = ctx.Add<Account>();

    account.CreationDate = DateTime.Now;
    account.Name = "Super account";

    ctx.Save();
}

T Update<T>(T entity, string[] changedProperties)

  • Updates an entity
  • Type parameter:
    • T : EntityBase - Type of the entity
  • Parameters:
    • T entity - Entity's data
    • string[] changedProperties - Properties changed

Usage:

using (var ctx = new AppContext(new AppConfiguration()))
{
    var account = ctx.Update(new Account
    {
        AccountId = 15,
        LastAction = DateTime.Now, // should be done using `IAdditionalStep`. Here only for learning purposes
        Name = "Super mega account"
    }, new[] { "LastAction", "Name" });

    ctx.Save();
}

void Delete<T>(T entity)

  • Marks an entity for removal
  • Type parameter:
    • T : EntityBase - Type of the entity
  • Parameters:
    • T entity - Entity's data

Usage:

using (var ctx = new AppContext(new AppConfiguration()))
{
    var account = ctx.GetRepository<Account>().GetById(id);
    ctx.Delete(account);
    ctx.Save();
}

void DeleteWhere<T>(Expression<Func<T, bool>> where)

  • Marks a group of entities for removal
  • Type parameter:
    • T : EntityBase - Type of the entity
  • Parameters:
    • Expression<Func<T, bool>> where - Expression to filter data to be removed

Usage:

using (var ctx = new AppContext(new AppConfiguration()))
{
    var ids = new [] { 15, 22, 351, 11 };
    
    ctx.DeleteWhere<Account>(a => ids.Contains(a.AccountId));
    ctx.DeleteWhere<Account>(a => a.CreationDate < DateTime.Now);
    ctx.Save();
}

Save

void Save(bool disposeAfter = true)

  • Saves the attached entities
  • Parameters:
    • bool disposeAfter - If true, maintains the entities in memory for further access, else removes context from memory

If you need to access data from the saved entity/record, make sure you set disposeAfter to false. Otherwise the object will have been disposed after the Save call. (see examples below)

Usage:

See Performing CRUD operations for several examples

Dispose

void Dispose()

  • Removes the context from memory

Usage:

Usually you won't need to use this method, since most people use the using context wrapper. But if you are creating your custom context handler, than you'll need it.

LoggedUser

object LoggedUser

  • Logged user. There's not secret here, a simple property in which we inform the logged user, if any.

Usage:

using (var ctx = new AppContext(new AppConfiguration()))
{
    ctx.LoggedUser = ctx.GetRepository<User, UserRepository>()
       .GetByUsername("mr_user"); // repository specific method
    
    ctx.DeleteWhere<Account>(a => ids.Contains(a.AccountId));
    ctx.Save();
}

Even though this works fine, if you need to set the logged user most of the times, I'd recommend creating a wrapper class that handles the context's creation and disposal and there you set the logged user.

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