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• Zod filtered array schema

  08-04-25, 08:38

  /**
   * Creates a Zod schema for an array that filters out invalid elements during preprocessing.
   *
   * @template T - Type extending ZodSchema
   * @param {T} schema - The Zod schema to validate individual array elements
   * @returns {ZodEffects<ZodArray<T>>} A new Zod schema that:
   * 1. Converts non-array inputs into single-element arrays
   * 2. Filters out elements that don't match the provided schema
   * 3. Validates the resulting array against the schema
   *
   * @example
   * const numberSchema = makeFilteredArraySchema(z.number());
   * numberSchema.parse(['1', 2, '3', 4]); // Returns [2, 4]
   */
  function makeFilteredArraySchema<T extends ZodSchema>(schema: T) {
    return z.preprocess((val) => {
      const array = Array.isArray(val) ? val : [val];
      return array.filter((item: unknown) => schema.safeParse(item).success);
    }, z.array(schema));
  }

• Typesafe Object.entries()

  30-01-25, 23:17

  export function objectEntries<T extends object>(
    obj: T,
  ): [keyof T, T[keyof T]][] {
    return Object.entries(obj) as [keyof T, T[keyof T]][];
  }

• TanStack Query setup for offline caching

  28-01-25, 18:07

  Code snippet to easily setup offline caching for TanStack Query in a React Native app.

  import { persister } from "@/lib/mmkv";
  import { QueryClient, onlineManager } from "@tanstack/react-query";
  import { PersistQueryClientProvider } from "@tanstack/react-query-persist-client";
  import { useEffect, type PropsWithChildren } from "react";
  import { useReactQueryDevTools } from "@dev-plugins/react-query";
  import NetInfo from "@react-native-community/netinfo";
  
  const queryClient = new QueryClient({
    defaultOptions: {
      queries: {
        staleTime: Number.POSITIVE_INFINITY,
        gcTime: Number.POSITIVE_INFINITY,
      },
    },
  });
  
  export function QueryProvider({ children }: PropsWithChildren) {
    useReactQueryDevTools(queryClient);
  
    useEffect(() => {
      return NetInfo.addEventListener((state) => {
        const status = !!state.isConnected;
        onlineManager.setOnline(status);
      });
    }, []);
  
    return (
      <PersistQueryClientProvider
        client={queryClient}
        onSuccess={() =>
          queryClient
            .resumePausedMutations()
            .then(() => queryClient.invalidateQueries())
        }
        persistOptions={{ persister, maxAge: Number.POSITIVE_INFINITY }}
      >
        {children}
      </PersistQueryClientProvider>
    );
  }