Description
I have a function with the following signature:
() =>
| {|
something: {
isConnected: boolean,
},
isLoading: boolean
|}
| {|
something: null,
isLoading: boolean
|}
>
As you can see, it can return two possible objects, one with a something property which has content and that same objet with null in that property.
I want to use some utility types to pick the non null version of the something property. I tried the following:
type Something = $NonMaybeType<
$PropertyType<
$Call<
() =>
| {|
something: {
connectionError: string,
},
isLoading: boolean
|}
| {|
something: null,
isLoading: boolean
|}
>,
"something"
>
>
But when I pass any object type with the generated type I still get errors telling me that empty (the null version) is not compatible with object (the thing the function is expecting).
How can I pick the right property of the right side of the sum type?
It can be seen how flow picks the property from the first value of the enum because if I try to nest picks (or elementypes) it says that null does not have any property:
type BambooIntegration = $NonMaybeType<
$ElementType<
$ElementType<
$Call<
() =>
| {|
something: {
isConnected: boolean,
},
isLoading: boolean
|}
| {|
something: null,
isLoading: boolean
|}
>,
"something"
>,{}>
>
// => 18: >,{}>
^ Cannot instantiate `$ElementType` because null [1] does not have properties. [incompatible-use]
References:
13: something: null,
^ [1]
Expected behavior
I expect to get a sum type of the nested property or being able to choose which side of the sum type I want to pick
Actual behavior
It picks the first value (in this case null) from the sum type
Activity