Best practices: Use schema validation along classes

Hello,

This issue is not related to a Zod problem, but I’m sure people using the lib can help me ❤️

This is a simple Schema (we have to imagine it is more complex):

export const PersonSchema = z.object({
    id: z.string(),
    firstname: z.string(),
    lastname: z.string()
});

export type PersonType = z.infer<typeof PersonSchema>;

On server side, when I get a POST request, I can validate the payload using:

const newPerson = PersonSchema.parse(payload);

Great, my noSQL database will stay clean !

But now, I want to use this on client-side. So I use the same method.

const newPerson = PersonSchema.parse(payload);

My front get a Person object now, but to display it, I would like to use a class method like this for example:

newPerson.getFullName();

But newPerson is not a class instance…

So far, I found those solutions:

Solution 1:

Create a class Person:

class PersonClass implements PersonType {
    id: ZodString['_output'];
    lastname: ZodString['_output'];
    firstName: ZodString['_output'];

    constructor(newPerson: PersonType) {
        this.id = newPerson.contactEmail;
        this.lastname = newPerson.lastname;
        this.firstname = newPerson.firstname;
    }

    getFullName() {
        return this.firstname + " "  + this.lastname;
    }

OR

class PersonClass implements PersonType {
    id: z.infer<typeof PersonSchema.shape.name>;
    lastname: z.infer<typeof PersonSchema.shape.name>;
    firstName: z.infer<typeof PersonSchema.shape.name>;

    constructor(newPerson: PersonType) {
        this.id = newPerson.contactEmail;
        this.lastname = newPerson.lastname;
        this.firstname = newPerson.firstname;
    }
    
    getFullName() {
        return this.firstname + " "  + this.lastname;
    }
}

I found this on the same subject:

https://github.com/colinhacks/zod/issues/38

But the more Person will have attributes, the more the class size is also growing. And I will have to parse my object, then to make an instance of the class…

Solution 2:

I don’t use classes, and I create a getFullName() methods like this:

const getFullName = (person: PersonType) => {return person.firstname + " " + person.lastname;}

So my question is:

How and when do you use Zod in your projects ?

Only to validate payloads ? How to use methods on parsed objects?

[X-Titouan]

export function create(data: unknown) {
  return {
    ...person.parse(data),
    getFullName: function (this: Person) {
      return `${this.firstName} ${this.lastName}`;
    }
  };
}

This is a great idea ! I think I will use this “factory” to add all my “class” functions to all objects !

[scotttrinh]

Closing, but feel free to add any additional thoughts here. If we want this to be an ongoing discussion point, we can also migrate this to a GitHub discussion.