46 lines
1.3 KiB
TypeScript
46 lines
1.3 KiB
TypeScript
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import { ApiError } from './api'
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/** Per-field validation messages: a 422 body's `{ errors: { field: [msg] } }`. */
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export type FieldErrors = Record<string, string[]>
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function isStringArray(value: unknown): value is string[] {
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return Array.isArray(value) && value.every((item) => typeof item === 'string')
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}
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/**
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* Extract the `{ errors: { field: [...] } }` map from a 422 ApiError body.
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* Returns null for anything that isn't a well-formed 422 field-error response
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* (wrong status, non-ApiError, non-JSON body, or a malformed errors shape) so
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* the caller can fall back to a generic error message.
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*/
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export function parseFieldErrors(error: unknown): FieldErrors | null {
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if (!(error instanceof ApiError) || error.status !== 422) {
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return null
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}
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let parsed: unknown
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try {
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parsed = JSON.parse(error.body)
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} catch {
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return null
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}
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if (
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typeof parsed !== 'object' ||
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parsed === null ||
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!('errors' in parsed) ||
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typeof parsed.errors !== 'object' ||
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parsed.errors === null
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) {
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return null
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}
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// Only accept the contract shape: every field maps to an array of strings.
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const entries = Object.entries(parsed.errors as Record<string, unknown>)
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if (!entries.every(([, messages]) => isStringArray(messages))) {
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return null
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}
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return parsed.errors as FieldErrors
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}
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