partialSafeParse.ts

import { z } from 'zod'
import { mapValues, omit, pick } from 'lodash'

function partialSafeParse<Schema extends z.ZodObject<any>> ( schema: Schema, input: unknown ) {
    const result = schema.safeParse( input )
    if ( result.success ) return result

    const { fieldErrors, formErrors } = result.error.flatten()
    if ( formErrors.length ) return result

    const inputObj = input as z.infer<Schema>
    const keysWithInvalidData = Object.keys( fieldErrors )
    const validInput = omit( inputObj, keysWithInvalidData )
    const invalidData = pick( inputObj, keysWithInvalidData )

    const validData = schema
        .omit( mapValues( fieldErrors, () => true as const ) )
        .parse( validInput )

    return {
        success: 'partial',
        validData,
        invalidData,
        fieldErrors,
    }
}

const userSchema = z.object( { name: z.string(), age: z.number() } )

console.log( partialSafeParse( userSchema, { name: 'foo', age: 42 } ) )
// { success: true, data: { name: "foo", age: 42 } }

console.log( partialSafeParse( userSchema, { name: null, age: 42 } ) )
// {
//   success: "partial",
//   validData: { age: 42 },
//   invalidData: { name: null },
//   fieldErrors: { name: [ "Expected string, received null" ] }
// }

console.log( partialSafeParse( userSchema, { name: null } ) )
// {
//   success: "partial",
//   validData: {},
//   invalidData: { name: null },
//   fieldErrors: { name: [ "Expected string, received null" ], age: [ "Required" ] }
// }

console.log( partialSafeParse( userSchema, {} ) )
// {
//   success: "partial",
//   validData: {},
//   invalidData: {},
//   fieldErrors: { name: [ "Required" ], age: [ "Required" ] }
// }

console.log( partialSafeParse( userSchema, null ) )
// {
//   success: false,
//   error: ZodError: [
//   {
//     "code": "invalid_type",
//     "expected": "object",
//     "received": "null",
//     "path": [],
//     "message": "Expected object, received null"
//   }
// ]
//     at handleResult (https://deno.land/x/zod@v3.20.2/types.ts:94:19)
//     at ZodObject.safeParse (https://deno.land/x/zod@v3.20.2/types.ts:231:12)
//     at partialSafeParse (file:///C:/_Software/deno-sandbox/zod/mod.ts:16:27)
//     at file:///C:/_Software/deno-sandbox/zod/mod.ts:44:14
// }