Use linq to generate direct update without select

Question

G\'day everyone.

I\'m still learning LINQ so forgive me if this is naive. When you\'re dealing with SQL directly, you can generate update commands with conditionals

Answer 1

Use this extension method: EntityExtensionMethods.cs

public static void UpdateOnSubmit(this Table table, TEntity entity, TEntity original = null)
    where TEntity : class, new()
{
    if (original == null)
    {
        // Create original object with only primary keys set
        original = new TEntity();
        var entityType = typeof(TEntity);
        var dataMembers = table.Context.Mapping.GetMetaType(entityType).DataMembers;
        foreach (var member in dataMembers.Where(m => m.IsPrimaryKey))
        {
            var propValue = entityType.GetProperty(member.Name).GetValue(entity, null);
            entityType.InvokeMember(member.Name, BindingFlags.SetProperty, Type.DefaultBinder,
                original, new[] { propValue });
        }
    }

    // This will update all columns that are not set in 'original' object. For
    // this to work, entity has to have UpdateCheck=Never for all properties except
    // for primary keys. This will update the record without querying it first.
    table.Attach(entity, original);
}

To use it, make sure the entity object that you pass to UpdateOnSubmit method has all the primary key properties set for the record you want to update. This method will then update the record with the remaining properties from the entity object without pulling the record first.

After calling UpdateOnSubmit, make sure to call SubmitChanges() for changes to apply.