This topic is mainly focused on performing CRUD operations using entity framework at runtime. That is, we can choose to which Table/DbSet we can CRUD data.
Prerequisite
Lets create a DbContext MyDbContext with 2 DbSets Animals and Birds.
public class MyDbContext : DbContext
{
public DbSet<Animal> Animals { get; set; }
public DbSet<Bird> Birds { get; set; }
}
public class Animal : LivingThing
{
public int NumberOfTeeths { get; set; }
public int RunningSpeed { get; set; }
}
public class Bird : LivingThing
{
public int MaxFlyingDistance { get; set; }
public int IsHerbivorous { get; set; }
}
public class LivingThing
{
public int Id { get; set; }
public string Name { get; set; }
}
Create
- To create an instance of a
AnimalorBirdentity. First get access to theDbSet<>by its name. Then take the firstTypefrom its generic arguments.
var entityType = _dbContext.GetType().GetProperty("Animals").PropertyType.GetGenericArguments().FirstOrDefault();
object livingThing = Activator.CreateInstance(entityType) as LivingThing;
-
Activatorcan be used to create an instance of a given 'Type'. - Now you can set commonly available properties such as
IdandNamedirectly and properties which are specific to an entity can set using reflection.
livingThing.Id = 1;
livingThing.Name = "Tiger";
// Set other properties dynamically
Dictionary<string, int> otherProperties = new Dictionary<string, int>()
{
{ "NumberOfTeeths", 10 },
{ "RunningSpeed", 50 },
}
// This will set all the properties which are specific to a class.
foreach(var prop in otherProperties.Keys)
{
string propertyValue = otherProperties[prop];
livingThing.GetType().GetProperty(prop).SetValue(livingThing, propertyValue);
}
- Add the entity
_dbContext.Add(livingThing);
_dbContext.SaveChanges();
Read
- Get the IQueryable<> property through reflection
var linqQuery = _dbContext.GetType().GetProperty("Animals").GetValue(_dbContext) as IQueryable<LivingThing>;
var entity = linqQurey.Where(x => x.Id == 1).First();
Update
- Get the entity by
Id, update properties and callSaveChanges()to update the entity.
var linqQuery = _dbContext.GetType().GetProperty("Animals").GetValue(_dbContext) as IQueryable<LivingThing>;
var entity = linqQurey.AsTracking().Where(x => x.Id == 1).First();
entity.Name = "New Name";
...
...
_dbContext.SaveChanges();
Delete
- Get the entity by
Id. UseRemove()to delete the entity.
var linqQuery = _dbContext.GetType().GetProperty("Animals").GetValue(_dbContext) as IQueryable<LivingThing>;
var entity = linqQurey.AsTracking().Where(x => x.Id == 1).First();
_dbContext.Remove(entity);
_dbContext.SaveChanges();
Thanks for reading...
Top comments (0)