DynamicData - Automatic Column Update

Articles in this Series

• Introduction - A DynamicData Attribute Based Permission Solution using User Roles.
• Part 1 - Permissions Attribute (Metadata) Classes.
• Part 2 - Sample Metadata for project.
• Part 3 - The Helper Extension Methods.
• Part 4 - Limit Tables shown on Default page and List, Edit & Details etc.
• Part 5 - Generate Columns/Rows (using IAutoFieldGenerator)
• Part 6 - Miscellaneous bits
• Part 7 - Updating the ListDetails Page
• DynamicData - Limit the Filter Fields
• DynamicData - Automatic Column Update

Automatic Column Update

The problem I'm trying to address is lets say you have the same columns on each table for simple auditing to check:

1. Who created the record and when
2. Who updated the record last and when

We will use the Northwind database for this test with a little tweaking.

We will use the Customers table in Northwind and add four columns:

1. CreatedBy String
2. CreatedOn DateTime
3. UpdatedBy String
4. UpdatedOn DateTime

These columns don’t need to be shown on any pages so scaffolding needs to be turned off see Listing 1

[MetadataType(typeof(CustomerMetadata))]
public partial class Customer
{
}

public class CustomerMetadata
{
    [ScaffoldColumn(false)]
    public Object UpdatedBy { get; set; }
    [ScaffoldColumn(false)]
    public Object UpdatedOn { get; set; }
    [ScaffoldColumn(false)]
    public Object CreatedBy { get; set; }
    [ScaffoldColumn(false)]
    public Object CreatedOn { get; set; }

}
Listing 1

To automatically update this table each time a row is created or update the DataContext partial class will need to be extended see Listing 2 in the DataContext each table has a partial method that can be implemented. The two needed for adding auditing data are InsertTableName and UpdateTableName where TableName is the name of the table that is to have auditing added.

public partial class NorthwindDataContext : System.Data.Linq.DataContext
{
    partial void InsertCustomer(Customer instance)
    {
        var user = HttpContext.Current.User;
        instance.CreatedBy = user.Identity.Name;
        instance.CreatedOn = DateTime.Now;
        instance.UpdatedBy = user.Identity.Name;
        instance.UpdatedOn = DateTime.Now;

        // finally send this to the DB
        this.ExecuteDynamicInsert(instance);
    }

    partial void UpdateCustomer(Customer instance)
    {
        var user = HttpContext.Current.User;
        instance.UpdatedBy = user.Identity.Name;
        instance.UpdatedOn = DateTime.Now;

        // finally send this to the DB
        this.ExecuteDynamicUpdate(instance);
    }
}
Listing 2

Now when a new record is created in the Customer table the four fields will be updated automatically and because the scaffolding metadata the columns will not be show in the DynamicData app.

Note: This will also work with Linq to SQL.