How to trim all char fields (C# string) before writing to database for all tables and all add or updates in EF Core?

I want EF Core to trim all char fields (C# strings) automatically before writing to the database for all tables (entities) and all add or update operations.

You can achieve this by overriding the SaveChanges method of your DbContext class. In the overridden method, you can iterate through all the entities in the ChangeTracker and trim all the string properties before saving the changes to the database.

** AppDbContext.cs **
public partial class AppDbContext : DbContext
{
    public AppDbContext(DbContextOptions<AppDbContext> options)
        : base(options)
    {
    }

    public virtual DbSet<Company> Companies { get; set; }
    ... // other DbSets

    protected override void OnModelCreating(ModelBuilder modelBuilder)
    {
      ...
    }

    partial void OnModelCreatingPartial(ModelBuilder modelBuilder);
}

** AppDbContextPartial.cs **
public partial class AppDbContext
{
    public override async Task<int> SaveChangesAsync(CancellationToken cancellationToken = default)
    {
        TrimStringProperties();
        return await base.SaveChangesAsync(cancellationToken);
    }

    private void TrimStringProperties()
    {
        var entries = ChangeTracker.Entries()
            .Where(e => e.State == EntityState.Added || e.State == EntityState.Modified);

        foreach (var entry in entries)
        {
            foreach (var property in entry.Properties)
            {
                if (property.CurrentValue is string stringValue)
                {
                    property.CurrentValue = stringValue.Trim(); // here
                }
            }
        }
    }
}