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Non-null assertion type operator ! #14366
Description
Activity
This requires a null assertion type operator, as you noted. something of the form
type Baz = (Foo["bar"])!["baz"];.Also referenced in #13253
- changed the title
[-]Lookup Types lookup fails for nullable types when "strictNullChecks" is on[/-][+]Assertion type operator `!`[/+]on Mar 2, 2017 - changed the title
[-]Assertion type operator `!`[/-][+]Null assertion type operator `!`[/+]on Mar 2, 2017 Related #12636
Another dupe: #17370
As it seems a special operator for this is no longer planned (see #17948 (comment)), I added an example for this at 4d14c9f now.
@tycho01 This still possible somehow? Apparently the syntax used in your example is no longer valid.
I'm trying to achieve the opposite of
Partial<T>to describe initialized (i.e defaults applied) to option objects (a mix of optional and required properties).The following would be possible if
!operator orAssert<T>were available:/** * Make all properties in T required */ type Whole<T> = { [P in keyof T]!: T[P]; };Is there any alternatives?
Reacted by Kristian Hanekampcvsguimaraes: it's an outstanding PR, it has never been possible yet on
master. The current topic is just a sub-case of #4183.Reacted by bykbtzrReacted by bykbtzrIt's not perfect, but a workaround for the example at the top is to do
type Baz = (Foo["bar"] & {"baz": {}})["baz"];
to get the deeper type. it does make the type
number & {}but it at least makes the above code workTo simplify that, i made the following helper (called
Getbecause of_.get):type Getter<T, K extends string> = T & Record<K, {}>; type Get<T, K extends keyof Getter<T, K>> = Getter<T, K>[K]; // Usage: type Baz = Get<Foo["bar"], "baz">;
Fixed in #22094 by tweaking the compiler to allow partial unions for indexed types - therefore not requiring a null assertion operator.
a
NonNullabletype was part of #21847- changed the title
[-]Null assertion type operator `!`[/-][+]Non-null assertion type operator `!`[/+]on Mar 1, 2018 Discussed this again in #22445. Conclusion, with
NonNullableavailable now with conditional types, the original scenario should be unblocked, no reason to add new rules.Reacted by kiara- locked and limited conversation to collaborators
on Jul 25, 2018
TypeScript Version: 2.2.1
Code
Expected behavior:
I would expect there to be a way to specify
baris non-null, such asFoo["bar!"].Actual behavior:
The code doesn't compile with the following error message:
"Property 'baz' does not exist on type '{ baz: number; } | null'."