prisma-map v1.0.4

prisma-map

Map generated Prisma types and runtime field values however you like.

This has not been extensively tested or benchmarked, but I don't expect any major issues.

Install

npm i prisma-map

Usage

This package provides two exports which must both be used for best results:

1. A Prisma client extension for mapping runtime field values.
2. A Prisma generator for mapping Prisma client's TypeScript types.

Use the client extension for modifying runtime values returned by your Prisma client. Use the generator to fix Prisma's generated types (so they match your value modifications).

Prisma Client Extension

The Prisma client extension can be added to your Prisma client either with createPrismaMapExtension (for super easy all-inclusive Prisma client extension) or runPrismaMapExtension (for including value mapping functionality into existing Prisma client extensions):

import {PrismaClient} from '@prisma/client';
import {createPrismaMapExtension, runPrismaMapExtension, type PrismaValueMapper} from 'prisma-map';

/** This function maps Date values to their corresponding ISO strings and will result in all */
function dateToString(value: unknown) {
    if (!(value instanceof Date)) {
        /** Return `undefined` inside a mapper to skip modifying the field value. */
        return undefined;
    }

    /** Return a replacement value inside of an object like this: */
    return {
        replacement: value.toISOString(),
    };
}

/** Create a list of mappers for the Prisma client extension. */
const mappers: PrismaValueMapper[] = [dateToString];

/** For a convenient one-shot extension, use `createPrismaMapExtension`. */
const prismaClient = new PrismaClient().$extends(createPrismaMapExtension(mappers));

/**
 * If you already have Prisma extensions, you can alternatively utilize runPrismaMapExtension for
 * the same results.
 */
const prismaClient2 = new PrismaClient().$extends({
    query: {
        async $allOperations({args, query}) {
            return await runPrismaMapExtension(mappers, {args, query});
        },
    },
});

Prisma Generator

The Prisma generator must be added to your schema.prisma file. It must be placed after the prisma-client-js generator:

generator jsClient {
    provider = "prisma-client-js"
    output   = "prisma-output"
}

generator mappedClient {
    provider = "prisma-map"
    config   = "./config.ts"
}

datasource db {
    provider = "sqlite"
    url      = "file:./db.db"
}

model User {
    id        String   @id @default(cuid(2))
    createdAt DateTime @default(now())

    email String
}

The prisma-map generator requires a config option, which must point to a TypeScript or JavaScript file with a default export of a valid mapping config file:

import {definePrismaMapConfig} from 'prisma-map';

export default definePrismaMapConfig({
    /** An optional list of import strings which will be prepended to the generated Prisma types. */
    imports: [
        "import {UtcIsoString} from 'date-vir';",
    ],
    /** An optional list of replacements that will be performed on Prisma's generated types file. */
    replacements: {
        /** Replace Prisma input types. */
        inputs: [
            {
                /** `match` can be a RegExp instance or a string. */
                match: /\bDate\b/,
                /**
                 * Replace is always a string. Note that you can use RegExp capture groups here
                 * (like `'$1'`).
                 */
                replace: 'UtcIsoString',
            },
        ],
        /** Replace Prisma output types. */
        outputs: [
            {
                match: /\bDate\b/,
                replace: 'UtcIsoString',
            },
        ],
    },
});