DEV Community

Nakul
Nakul

Posted on

How to CRUD dynamically in Entity Framework

#csharp #dotnet #entityframework

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; } }
Enter fullscreen mode Exit fullscreen mode

Create

  • To create an instance of a Animal or Bird entity. First get access to the DbSet<> by its name. Then take the first Type from its generic arguments. 
var entityType = _dbContext.GetType().GetProperty("Animals").PropertyType.GetGenericArguments().FirstOrDefault(); object livingThing = Activator.CreateInstance(entityType) as LivingThing;
Enter fullscreen mode Exit fullscreen mode
  • Activator can be used to create an instance of a given 'Type'.
  • Now you can set commonly available properties such as Id and Name directly 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); }
Enter fullscreen mode Exit fullscreen mode
  • Add the entity 
_dbContext.Add(livingThing); _dbContext.SaveChanges();
Enter fullscreen mode Exit fullscreen mode

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();
Enter fullscreen mode Exit fullscreen mode

Update

  • Get the entity by Id, update properties and call SaveChanges() 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();
Enter fullscreen mode Exit fullscreen mode

Delete

  • Get the entity by Id. Use Remove() 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();
Enter fullscreen mode Exit fullscreen mode

Thanks for reading...

Top comments (0)