Handling Null Column Values in Dataverse: Best Practices for Early and Late Bound Classes

When working with Microsoft Dataverse, dealing with null values in table columns is a common challenge. Null values can represent missing or undefined data, and how you handle them can significantly impact the behavior and reliability of your applications. This blog post will guide you through the nuances of working with null column values in Dataverse, especially focusing on the differences between early bound and late bound classes.

Understanding Null Values in Dataverse

In Dataverse, when a table column contains a null value or if the column wasn’t explicitly requested, that column won’t appear in the Entity.Attributes collection. This means there won’t be a key to access or a value to return. Essentially, the absence of an attribute in the collection indicates that its value is null.

Moreover, certain columns are inherently not valid for reading and will always return null values. These columns are defined with the AttributeMetadata.IsValidForRead property set to false.

Early Bound Classes: Simplifying Null Value Handling

When you use early bound classes, which are strongly typed classes generated based on the metadata of your Dataverse entities, handling null values becomes straightforward. The properties of these generated classes automatically manage null values. If a column has a null value, accessing the property corresponding to that column will return null, without throwing any exceptions or requiring additional checks.

Example:

var revenue = account.Revenue; // Returns null if the 'revenue' column is null

Early bound classes abstract away the complexity of dealing with null values, making your code cleaner and less error-prone.

Late Bound Classes: Mitigating Null Values

When working with late bound classes, which involve accessing columns using the Entity.Attributes collection, handling null values requires more care. Attempting to access a null column using an indexer on the Entity.Attributes or Entity.FormattedValues collections can result in a KeyNotFoundException, with the message “The given key was not present in the dictionary.”

Strategies to Mitigate Null Values in Late Bound Classes:

1. Check for Existence Before Accessing:Before accessing a column that could be null, use the Entity.Contains(System.String) method to check whether the column is present in the Entity.Attributes collection. If the column is present, you can safely access its value.
   
   Example:
   

   Money revenue = entity.Contains("revenue") ? (Money)entity["revenue"] : null; 

   
   This approach ensures that you only attempt to access the value if the column exists, preventing any KeyNotFoundException from being thrown.
   
2. Use the Entity.GetAttributeValue<T>(System.String) Method:The Entity.GetAttributeValue<T>(System.String) method provides a more concise way to access column values while handling nulls. If the column value is null, this method returns null for reference types or the default value for value types (e.g., false for Boolean, DateTime.MinValue for DateTime).
   
   Example:
   

   Money revenue = entity.GetAttributeValue<Money>("revenue"); 

   
   This method is particularly useful because it avoids the need for explicit null checks and can streamline your code.

Important Considerations

When using the Entity.GetAttributeValue<T>(System.String) method with value types (e.g., Boolean, DateTime), it’s important to note that the method will return the default value for that type if the column value is null. This behavior is different from reference types, which would simply return null.

Example:

bool isActive = entity.GetAttributeValue<bool>("isactive");
DateTime createdOn = entity.GetAttributeValue<DateTime>("createdon");

Being aware of this behavior is crucial to avoid unintended logic errors in your code, especially when working with date and boolean fields.

Handling null values in Dataverse requires a clear understanding of the differences between early bound and late bound classes. Early bound classes simplify the process by abstracting null checks, while late bound classes offer more control but require careful handling to avoid exceptions. By leveraging methods like Entity.Contains and Entity.GetAttributeValue<T>, you can write more robust and error-free code when working with late bound classes.

Whether you’re working with early or late bound classes, understanding these nuances will help you manage null values more effectively, leading to more reliable and maintainable Dataverse applications.