rspec/rules/S7105/dart/rule.adoc

== Why is this an issue?

Nullability of types is an important part of Dart's type system. In order to simplify the work with nullable types in the Dart language there are many null-aware operators (`??`, `??=`, `?.`, `!`, `?..`, `?[]`, ``++...?++``). Using those operators will make your code more clear and concise.

The If-null operator (`??`), will check if the value on the left side is `null`, and, if yes, will return the expression on the right. This is an easy way to set default values instead of dealing with `null`. Thus, this operator doesn't make sense if used with `null` on either sides.

For example, in `null ?? x` the `x` will always be returned. Using the operator here only introduces confusion and additional cognitive load. In case of `x ?? null`, again the result will always be the value of `x`. In both cases the operator can be replaced with just `x`.

== How to fix it

Depending on your context, remove the `null ??` / `null ??` part, or replace `null` with some meaningful value.

=== Code examples

==== Noncompliant code example

[source,dart,diff-id=1,diff-type=noncompliant]
----
void f(String? s) {
  var myString1 = s ?? null;
  var myString2 = null ?? s;
  var myString3 = s ?? null;
}
----

==== Compliant solution

[source,dart,diff-id=1,diff-type=compliant]
----
void f(String? s) {
  var my_string1 = s;
  var my_string2 = s;
  var my_string3 = s ?? "default";
}
----

== Resources

=== Documentation

* Dart Docs - https://dart.dev/tools/linter-rules/unnecessary_null_in_if_null_operators[Dart Linter rule - unnecessary_null_in_if_null_operators]


ifdef::env-github,rspecator-view[]

'''
== Implementation Specification
(visible only on this page)

=== Message

Unnecessary use of '??' with 'null'.

=== Highlighting

Only `null` keyword

endif::env-github,rspecator-view[]