Handling the ‘Explicit change tracking required for the array field…’ warning

RELATED TO:

Article information

Article relates to

 Telerik OpenAccess ORM

Created by

 Alexander Filipov

Last modified

 April 9, 2012

Last modified by

 Pencho Popadiyn

DESCRIPTION

By default the OpenAccessContext silently manages the change tracking of the persistent objects. However, this is not possible for all types of fields that a class may contain. For example, changes in array fields could not be fully tracked by the object context. This limitation is present when an array field is not completely replaced with another array but only a certain element is changed. To notify the programmer for this behavior, Telerik OpenAccess ORM shows a warning at compile time with this limitation:
OpenAccess Warning: Explicit change tracking required for the array field Namespace.ClassName.FieldName

SOLUTION

When you change some value of an array, you will have to inform the context that you have made a changes, so that it can be persisted to the database.
The code below would not persist the change in the byte[] field named Picture from the Category object:

using (EntitiesModel dbContext = new EntitiesModel())
{
    Category category = dbContext.Categories.FirstOrDefault();
    category.Picture[1] = 0;
    dbContext.SaveChanges();
}

As the warning states, explicit change tracking is required in this case. This can be accomplished by using the OpenAccessContext.MakeDirty method. It marks a field as “dirty”, thereby the field value is forced to be stored in the database. Below is the same sample code that modifies one of the array elements but this time the change is persisted.

using (EntitiesModel dbContext = new EntitiesModel())
{
    Category category = dbContext.Categories.FirstOrDefault();
    category.Picture[1] = 0;
    dbContext.MakeDirty(category, "Picture");
    dbContext.SaveChanges();
}

The case when the whole array is replaced with another array does not require any additional operations. The change tracking is done internally:

using (EntitiesModel dbContext = new EntitiesModel())
{
    Category category = dbContext.Categories.FirstOrDefault();
    category.Picture = new byte[] { 0, 1, 2 };               
    dbContext.SaveChanges();
}

Related Products
Data Access

Resources Buy Try

More Resources

  • Forums

    Find answers to thousands of questions or reach out to our active community.

  • Videos

    Browse the Data Access videos to learn about handy features and tips and tricks.

  • Documentation

    Detailed help articles and API references for Telerik Data Access.

  • Knowledge Base

    Tutorials and working examples on how to achieve common scenarios.

  • Code Library

    Sample projects submitted by Telerik staff and community members.

  • Blog

    Stay up-to-date with the latest functionality, how-to articles, and industry trends.

  • Release History

    Up-to-date release notes for all new features and improvements.