ERM
ERM is a .NET Standard Object-Relational Mapping (ORM) tool developed mostly for educational/research purposes.
Basic Usage
First, create an object representing your database (here I'm using an example from Northwind)
class Customers
{
public string CustomerID { get; set; }
public string CompanyName { get; set; }
public string ContactName { get; set; }
public string ContactTitle { get; set; }
public string Address { get; set; }
public string City { get; set; }
public string Region { get; set; }
public string PostalCode { get; set; }
public string Country { get; set; }
public string Phone { get; set; }
public string Fax { get; set; }
}
We now need to add a custom attribute to this class. The Db attribute can be used to specify the connection string to be used for loading these entities.
[Db("Northwind")]
class Customers
{
public string CustomerID { get; set; }
public string CompanyName { get; set; }
public string ContactName { get; set; }
public string ContactTitle { get; set; }
public string Address { get; set; }
public string City { get; set; }
public string Region { get; set; }
public string PostalCode { get; set; }
public string Country { get; set; }
public string Phone { get; set; }
public string Fax { get; set; }
}
Great, that's our class set up.
To load our Customers, we first need to create a query by passing the class to the Db class' generic GetAll<T> method
Query query = Db.GetAll<Customer>();
We can set a "where" clause on this query if we want by using the .Where() method on the query. For example, to get all customers with the ID "AROUT":
Query query = Db.GetAll<Customer>();
query.Where(cust => cust.CustomerID == "AROUT");
Where returns a Query object so we can actually chain this call:
Query query = Db.GetAll<Customer>.Where(cust => cust.CustomerID == "AROUT");
And, finally, we need to execute the query to get our customers
Query query = Db.GetAll<Customer>();
query.Where(cust => cust.CustomerID == "AROUT");
List<Customer> customers = query.Execute();
or, in a chain:
List<Customer> customers = Db.GetAll<Customer>().Where(cust => cust.CustomerID == "AROUT").Execute();