ea3ad82654
## Review A dedicated reviewer checked the rule description successfully for: - [ ] logical errors and incorrect information - [ ] information gaps and missing content - [ ] text style and tone - [ ] PR summary and labels follow [the guidelines](https://github.com/SonarSource/rspec/#to-modify-an-existing-rule)
49 lines
1.6 KiB
Plaintext
49 lines
1.6 KiB
Plaintext
== Why is this an issue?
|
|
|
|
https://learn.microsoft.com/en-us/dotnet/api/system.nullable-1[Nullable value types] can hold either a value or `Nothing`.
|
|
|
|
The value stored in the nullable type can be accessed with the `Value` property or by casting it to the underlying type. Still, both operations throw an `InvalidOperationException` when the value is `Nothing`. A nullable type should always be tested before accessing the value to avoid raising exceptions.
|
|
|
|
== How to fix it
|
|
|
|
=== Code examples
|
|
|
|
==== Noncompliant code example
|
|
|
|
[source,vbnet,diff-id=1,diff-type=noncompliant]
|
|
----
|
|
Sub Sample(condition As Boolean)
|
|
Dim nullableValue As Integer? = If(condition, 42, Nothing)
|
|
Console.WriteLine(nullableValue.Value) ' Noncompliant: InvalidOperationException is raised
|
|
|
|
Dim nullableCast As Integer? = If(condition, 42, Nothing)
|
|
Console.WriteLine(CType(nullableCast, Integer)) ' Noncompliant: InvalidOperationException is raised
|
|
End Sub
|
|
----
|
|
|
|
==== Compliant solution
|
|
|
|
[source,vbnet,diff-id=1,diff-type=compliant]
|
|
----
|
|
Sub Sample(condition As Boolean)
|
|
Dim nullableValue As Integer? = If(condition, 42, Nothing)
|
|
If nullableValue.HasValue Then
|
|
Console.WriteLine(nullableValue.Value)
|
|
End If
|
|
|
|
Dim nullableCast As Integer? = If(condition, 42, Nothing)
|
|
If nullableCast.HasValue Then
|
|
Console.WriteLine(CType(nullableCast, Integer))
|
|
End If
|
|
End Sub
|
|
----
|
|
|
|
== Resources
|
|
|
|
=== Documentation
|
|
|
|
* https://learn.microsoft.com/en-us/dotnet/api/system.nullable-1[Nullable<T>]
|
|
* https://cwe.mitre.org/data/definitions/476[MITRE, CWE-476] - NULL Pointer Dereference
|
|
|
|
include::../rspecator-dotnet.adoc[]
|