How to update record using Entity Framework Core

Question

What is the best approach to update database table data in Entity Framework Core   Retrieve the table row  do the changes and save Use keyword Update in DB context and handle exception for item not exist  What are the improved features we can use over EF6

User · Accepted Answer

To update an entity with Entity Framework Core, this is the logical process:

Create instance for DbContext class
Retrieve entity by key
Make changes on entity's properties
Save changes

Update() method in DbContext:

Begins tracking the given entity in the Modified state such that it will be updated in the database when SaveChanges() is called.

Update method doesn't save changes in database; instead, it sets states for entries in DbContext instance.

So, We can invoke Update() method before to save changes in database.

I'll assume some object definitions to answer your question:

Database name is Store
Table name is Product

Product class definition:

public class Product
{
    public int? ProductID { get; set; }
    
    public string ProductName { get; set; }
    
    public string Description { get; set; }
    
    public decimal? UnitPrice { get; set; }
}

DbContext class definition:

public class StoreDbContext : DbContext
{
    public DbSet<Product> Products { get; set; }
    
    protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
    {
        optionsBuilder.UseSqlServer("Your Connection String");

        base.OnConfiguring(optionsBuilder);
    }
    
    protected override void OnModelCreating(ModelBuilder modelBuilder)
    {
        modelBuilder.Entity<Order>(entity =>
        {
            // Set key for entity
            entity.HasKey(p => p.ProductID);
        });
        
        base.OnModelCreating(modelBuilder);
    }
}

Logic to update entity:

using (var context = new StoreDbContext())
{
        // Retrieve entity by id
        // Answer for question #1
        var entity = context.Products.FirstOrDefault(item => item.ProductID == id);
        
        // Validate entity is not null
        if (entity != null)
        {
            // Answer for question #2

            // Make changes on entity
            entity.UnitPrice = 49.99m;
            entity.Description = "Collector's edition";
            
            /* If the entry is being tracked, then invoking update API is not needed. 
              The API only needs to be invoked if the entry was not tracked. 
              https://www.learnentityframeworkcore.com/dbcontext/modifying-data */
            // context.Products.Update(entity);
            
            // Save changes in database
            context.SaveChanges();
        }
}

User · Answer

Microsoft Docs gives us two approaches      Recommended HttpPost Edit code  Read and update   This is the same old way we used to do in previous versions of Entity Framework  and this is what Microsoft recommends for us   Advantages   Prevents overposting EFs automatic change tracking sets the Modified flag on the fields that are changed by form input       Alternative HttpPost Edit code  Create and attach   an alternative is to attach an entity created by the model binder to the EF context and mark it as modified   As mentioned in the other answer the read-first approach requires an extra database read  and can result in more complex code for handling concurrency conflicts

User · Answer

After going through all the answers I thought i will add two simple options  If you already accessed the record using FirstOrDefault   with tracking enabled  without using  AsNoTracking   function as it will disable tracking  and updated some fields then you can simply call context SaveChanges    In other case either you have entity posted to server using HtppPost or you disabled tracking for some reason then you should call context Update entityName  before context SaveChanges     1st option will only update the fields you changed but 2nd option will update all the fields in the database even though none of the field values were actually updated

User · Answer

According to Microsoft docs   the read-first approach requires an extra database read  and can result in more complex code for handling concurrency conflict  However  you should know that using Update method on DbContext will mark all the fields as modified and will include all of them in the query  If you want to update a subset of fields you should use the Attach method and then mark the desired field as modified manually  context Attach person   context Entry person  Property p   gt  p Name  IsModified   true  context SaveChanges

User · Answer

It s super simple using  var dbContext   new DbContextBuilder   BuildDbContext          dbContext Update entity       await dbContext SaveChangesAsync

User · Answer

A more generic approach To simplify this approach an  quot id quot  interface is used public interface IGuidKey       Guid Id   get  set       The helper method public static void Modify lt T gt  this DbSet lt T gt  set  Guid id  Action lt T gt  func      where T   class  IGuidKey  new         var target   new T               Id   id            var entry   set Attach target       func target       foreach  var property in entry Properties                var original   property OriginalValue          var current   property CurrentValue           if  ReferenceEquals original  current                         continue                     if  original    null                        property IsModified   true              continue                     var propertyIsModified    original Equals current           property IsModified   propertyIsModified           Usage dbContext Operations Modify id  x   gt    x Title    quot aaa quot

User · Answer

public async Task lt bool gt  Update MyObject item        Context Entry await Context MyDbSet FirstOrDefaultAsync x   gt  x Id    item Id   CurrentValues SetValues item       return  await Context SaveChangesAsync     gt  0

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