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* Add type guard, generic, and test * Improve generic naming * Add ErrorFSA alias * Write test correctly to avoid confusion * Add `someField` validation * Add somefield test * Add semi-colon, move tsc to posttest * Add 3 more semi-colon * Remove optional designation. Since `payload` and `meta` is generic, user can specify `void` or `undefined` to indicate it does not present. Removing the optional designation improves type guard. see `isCustomAction4()` for example * Fix more linting issue * Adding eslint for typescript. Update yarn.lock * Change typescript-eslint-parser to devDeps * Move eslint-plugin-typescirpt to devDeps also.
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,78 @@ | ||
| import { FluxStandardAction, isError, isFSA } from '../src'; | ||
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| interface CustomPayload { | ||
| a: number; | ||
| } | ||
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| interface CustomMetadata { | ||
| b: string; | ||
| } | ||
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| interface MyError extends Error { | ||
| someField: string; | ||
| } | ||
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| function createCustomAction(payload: CustomPayload) { | ||
| return { | ||
| type: 'custom', | ||
| payload | ||
| }; | ||
| } | ||
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| function isCustomAction(action: FluxStandardAction<any, any>): action is FluxStandardAction<CustomPayload, any> { | ||
| return isFSA(action) && action.type === 'custom'; | ||
| } | ||
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| function isCustomAction2(action: FluxStandardAction<any, any>): action is FluxStandardAction<CustomPayload, CustomMetadata> { | ||
| return isFSA(action) && action.type === 'custom2'; | ||
| } | ||
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| function isCustomAction3(action: any): action is FluxStandardAction<void, string> { | ||
| return isFSA(action) && action.type === 'custom3'; | ||
| } | ||
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| function isCustomAction4(action: any): action is FluxStandardAction<{ message: string }, void> { | ||
| return true; | ||
| } | ||
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| let action2 = {}; | ||
| if (isCustomAction4(action2)) { | ||
| // type guard infers payload will not be undefined | ||
| console.log(action2.payload.message); | ||
| } | ||
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| function reducer(state, action) { | ||
| if (isFSA<CustomPayload, void>(action)) { | ||
| let a: number = action.payload.a; | ||
| } | ||
| else if (isFSA<CustomPayload, CustomMetadata>(action)) { | ||
| let a: number = action.payload.a; | ||
| let b: string = action.meta.b; | ||
| } | ||
| else if (isFSA<void, string>(action)) { | ||
| let meta: string = action.meta; | ||
| } | ||
| else if (isError(action)) { | ||
| let iserr: true = action.error; // iserr === true | ||
| let err: Error = action.payload; | ||
| } | ||
| else if (isError<MyError, void>(action)) { | ||
| let err: MyError = action.payload; | ||
| let someFieldValue: string = err.someField; | ||
| } | ||
| } | ||
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| function reducer2(state, action) { | ||
| if (isCustomAction(action)) { | ||
| let a: number = action.payload.a; | ||
| } | ||
| else if (isCustomAction2(action)) { | ||
| let a: number = action.payload.a; | ||
| let b: string = action.meta.b; | ||
| } | ||
| else if (isCustomAction3(action)) { | ||
| let meta: string = action.meta; | ||
| } | ||
| } | ||
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| let action = createCustomAction({ a: 123 }); |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,10 @@ | ||
| { | ||
| "compilerOptions": { | ||
| "noEmit": true, | ||
| "strictNullChecks": true, | ||
| "target": "es5" | ||
| }, | ||
| "files": [ | ||
| "test/typings-test.ts" | ||
| ] | ||
| } |
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6a2898aThere was a problem hiding this comment.
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Hi @unional, I noticed that you changed the type of meta from optional
meta?: anyto requiredmeta: Meta.I think that might be a mistake. If not: Can you please explain the intent?
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Thanks for the question.
The original comment on that was here #45 (comment)
and
microsoft/TypeScript#12400
The idea is that when
PayloadandMetais defined by a custom action, the action author would expect the payload and meta to be non-optional.If defined as
meta?, then the user always have to check if it is not undefined on every usage.6a2898aThere was a problem hiding this comment.
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Hi @unional,
How would I define a FluxStandardAction without a Meta? I cannot find an according overload.
All my Actions (at the moment) have a Payload but not all of them need a Meta. Maybe there even could be actions that wouldn't need a payload? Would that be possible?
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Just do
FSA<MyPayload, undefined>. When generic default is available, it can be simplified back toFSA<MyPayload>. SeparatingMeta<M>on its own (as in the typing in DT) is interesting but it feels like a hack, making consuming code more cluttered IMO.Hope that helps
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I tried
FSA<MyPayload, undefined>and it kept telling me there was an error, so I had to addto my Action. What am I missing?
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Yes. See the TypeScript issue