Fix model types when extending in any way. #2218
Merged
Conversation
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Previously, we used to have TS resolve the extensions by just doing something like `A & B`. The problem is that in TypeScript that means "it's both A and B", but what happens if you have a required prop in one and an optional prop in the other? Well, the least common denominator wins, which is requiredness, because it satisfies both the required and optional properties. MST doesn't work that way though. Whenever we extend a model we "clobber" the old property of the same name. To model this in TS we need to omit properties from the previous version of the model and replace them with the newer ones.
thegedge
commented
Nov 9, 2024
| @@ -458,7 +468,7 @@ export class ModelType< | |||
| return this.cloneAndEnhance({ properties }) | |||
| } | |||
|
|
|||
| volatile<TP extends object>(fn: (self: Instance<this>) => TP) { | |||
There was a problem hiding this comment.
Changing all of these to be clearer. object is generally not what one wants.
I think what we want is only the last.
There was a problem hiding this comment.
I definitely agree here.
| fn: (self: Instance<this>) => { actions?: A; views?: V; state?: VS } | ||
| ): IModelType<PROPS, OTHERS & A & V & VS, CustomC, CustomS> | ||
| ): IModelType<PROPS, OmitMerge<OTHERS, A & V & VS>, CustomC, CustomS> |
There was a problem hiding this comment.
This is the fix for the issue, but I changed the above to resolve a similar issue.
Technically we likely want to deal with this in compose too, but I'd rather deal with that when I make compose use variadic tuples in the generic signature.
|
Thanks @thegedge! Will take a look this weekend. |
Closed
coolsoftwaretyler
approved these changes
Nov 10, 2024
Comment on lines
+1429
to
+1430
| anotherValue: "test" as string, | ||
| soManyValues: "test" as string |
There was a problem hiding this comment.
praise: many values, very wow.
| @@ -74,6 +73,9 @@ export interface ModelPropertiesDeclaration { | |||
| [key: string]: ModelPrimitive | IAnyType | |||
| } | |||
|
|
|||
| /** intersect two object types, but omit keys of B from A before doing so */ | |||
| type OmitMerge<A, B> = Omit<A, keyof B> & B | |||
| @@ -458,7 +468,7 @@ export class ModelType< | |||
| return this.cloneAndEnhance({ properties }) | |||
| } | |||
|
|
|||
| volatile<TP extends object>(fn: (self: Instance<this>) => TP) { | |||
There was a problem hiding this comment.
I definitely agree here.
This was referenced Dec 13, 2024
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
What does this PR do and why?
Fixes #2216
Previously, we used to have TS resolve the extensions by just doing something like
A & B. The problem is that in TypeScript that means "it's both A and B", but what happens if you have a required prop in one and an optional prop in the other? Well, the least common denominator wins, which is requiredness, because it satisfies both the required and optional properties.MST doesn't work that way though. Whenever we extend a model we "clobber" the old property of the same name. To model this in TS we need to omit properties from the previous version of the model and replace them with the newer ones.
Steps to validate locally
The added test should capture both the essence of the aforementioned issue, while also capturing other issues we have.