Introduction
Data Table in conjunction with dataset is a very common option for CRUD (Create, Read, Update and Delete) operation towards database interaction.This is true that data table is developer friendly and provides cool features but at the same time this is heavy, resource hungry and not object oriented. As a result, we can think of Generic List LIST<T>
as an introductory alternative of datatable and moving forward we will try to create a framework to provide the above CRUD functionality.
See below for the screen developed with the above framework.
A generic list is useful for creating a collection of similar objects. Generic List<T>
where T
is the Business Object / Business Entity / etc., which can be further strongly typed.
For example, List<Employee>
will allow only Employee
instance to be added to the list.
In the following framework, we have added a custom wrapper on the top of List<T>
for better readability.
public class EntityCollection<T> : List<T>{}
EntityCollection<T>
where T
refers to Business Entity/Object. Following is the way to insert as many entities into collection.
EntityCollection<userbo> objUserCollection = new EntityCollection<userbo>();
objUserCollection.Add(new UserBO (……));
objUserCollection.Add(new UserBO (……));
EntityCollection<cusbo> objCustCollection = new EntityCollection<cusbo>();
objUserCollection.Add(new CusBO (……));
objUserCollection.Add(new CusBO (……));
Implementing Search Feature
“FindByExpression
” custom method of EntityCollection
provides facility to filter data depending upon the expression passed as parameter. Expression should be given in “Property=Value
” format.
EntityCollection<userbo> userCollection = UserData();
userCollection = userCollection.FindByExpression("Name=Jhon");
EntityCollection<cusbo> objCustCollection = CustomerData();
objCustCollection = objCustCollection.FindByExpression("CustId=3451");
Let’s see the underlying logic of method “FindByExpression
”:
public static EntityCollection<t> FindByExpression<t>
(this EntityCollection<t> EntityCollection,string FindExpression)
{
Expression objExpression = GetPropertyInfo(EntityCollection, FindExpression, '=');
IEnumerable<t> objEntityList = EntityCollection.FindAll
(objC => objExpression.PropertyInfo.GetValue(objC, null).ToString()
== objExpression.ExpressionPropertyVal);
EntityCollection<t> objEntities = new EntityCollection<t>();
foreach (var objEntity in objEntityList) objEntities.Add(objEntity);
return objEntities;
}
The getPropertyInfo()
method returns metadata of find expression property and the value to be searched wrapped together in a class.
Afterwards, we are using FindAll
method of generic LIST
with lambda expression to find all the matches.
Implementing Sort Features
“SortByExpression
” custom method of EntityCollection
provides the facility to sort data depending upon the expression passed as parameter. Expression should be given in “Property Desc/Asc” format.
EntityCollection<userbo> userCollection = UserData();
userCollection = userCollection.SortByExpression ("Name");
EntityCollection<cusbo> objCustCollection = CustomerData();
objCustCollection = objCustCollection. SortByExpression ("CustId Desc");
Let’s understand the logic of “SortByExpression
”:
public static EntityCollection<t> SortByExpression
<t>(this EntityCollection<t> EntityCollection,string SortExpression)
{
bool blnDescending = false;
IEnumerable objEntityList;
Expression objExpression = GetPropertyInfo(EntityCollection, SortExpression, ' ');
blnDescending = SortExpression.ToUpper().Contains("DESC");
if (blnDescending) objEntityList =
EntityCollection.OrderByDescending
(objX =>objExpression.PropertyInfo.GetValue(objX, null));
else objEntityList = EntityCollection.OrderBy
(objX => objExpression.PropertyInfo.GetValue(objX, null));
EntityCollection<t> objEntities = new EntityCollection<t>();
foreach (var objEntity in objEntityList) objEntities.Add(objEntity);
return objEntities;
}
We are taking help of OrderBy
/OrderByDescending
method of generic LIST<t>
sort order.
Implementing Delete Feature
“DeleteByExpression
” custom method of EntityCollection
provides the facility to remove entity from collection depending upon the matches. Expression should be given in “Property=Value
” format.
EntityCollection<userbo> userCollection = UserData();
userCollection = userCollection.FindByExpression("Name=Jhon");
Let’s understand the logic of “DeleteByExpression
”:
public static EntityCollection<t> DeleteByExpression<t>
(this EntityCollection<t> EntityCollection,string FindExpression)
{
Expression objExpression = GetPropertyInfo(EntityCollection, FindExpression, '=');
IEnumerable<t> objEntityList = EntityCollection.FindAll
(objC =>objExpression.PropertyInfo.GetValue(objC, null).ToString()
== objExpression.ExpressionPropertyVal);
foreach (var objEntity in objEntityList) EntityCollection.Remove(objEntity);
return EntityCollection;
}
We are using FindAll
method of generic LIST
and eliminating the matches.
History
- 27th May, 2010: Initial post
Bibhas has 8 years of extensive experience in application development with exposure to business requirement study, system analysis and designing, coding ,testing,
implementation, end user training and client Interaction.
He was the part of application development team and worked for industry leading organizations like "ConocoPhillips", "Abbey National Bank" and “DHL".
Posses sound experience as a technical architect and all part of software development lifecycle.
His interest includes in Microsoft Technologies (ASP.NET 3.5 & SQL Server), Design Pattern and wide variety of internet technologies like AJAX, JQUERY etc.