56 lines
1.6 KiB
Markdown
56 lines
1.6 KiB
Markdown
# Reference Data Layer
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App-wide API-backed lookup datasets reused across modules — countries, languages, currencies, time zones, common option dictionaries. The layer fetches them, exposes reusable query hooks, and owns their cache keys.
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Small dataset → one file; larger → a folder:
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```plaintext
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refdata/
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├── countries.ts
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├── languages.ts
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└── currencies/
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├── api.ts
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├── dto.ts
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├── mapper.ts
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├── queries.ts
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└── keys.ts
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```
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## Rules
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1. App-wide datasets only — a dataset owned by one feature belongs in that module's `data/` layer.
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2. May use `#infrastructure/axios` and `#infrastructure/reactQuery`; must not import from `view/`, `pages/`, or feature modules.
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3. Expose hooks or small service functions — consumers should not know endpoints or cache keys.
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4. Add mappers when backend DTOs differ from app-facing data, tested like module data mappers.
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## Example
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```ts
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import { keepPreviousData, useQuery } from "@tanstack/react-query";
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import { axiosClient } from "#infrastructure/axios";
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import { createKeyBuilder } from "#infrastructure/reactQuery";
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export const countriesCacheKey = createKeyBuilder(
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"REF_DATA",
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"COUNTRIES",
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"LIST",
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);
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interface CountryData {
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code: string;
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name: string;
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}
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export const useCountries = () => {
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return useQuery({
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queryKey: countriesCacheKey.store(),
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placeholderData: keepPreviousData,
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queryFn: async () => {
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return axiosClient
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.get<Array<CountryData>>("/datasets/countries")
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.then((data) => data.data);
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},
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});
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};
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```
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