More Elegant Way For Type

Anyone know a better way to write this type? I feel like this is repetitive. Thx!

26 Replies

ippo•2y ago

do yourself a favor and do not use numbers for roles or permissions use descriptive texts like "admin", "user", "guest", "manager" and so on working with numbers, looking them up and try to understand what they mean is just a pain

Perfect•2y ago

rip - its quite late for me to change that in our project, but I will keep it in mind we only have three (0, 1, 2) 2 owner, 1 instructor, 0 student But I do see your point

Scot•2y ago

I second this, we used to have numbers thst corresponded to entry’s in a db where the name was kept It was awful Wasted so many engineer hours down the track

ippo•2y ago

@Alex | C4 model stan this sounds to me like a forced artificial id for roles 🙂

Scot•2y ago

It was because Java It used Java Emina Enums* Then in hibernate orm they would get numbers in the db Same with a lot of things It was terrible

ippo•2y ago

I saw so many developers creating tables and adding an id column just because, even if they have a unique identifier

Jon Higger (He / Him)•2y ago

Something like this could work

type BaseUser = {
   id: number
   name: string;
   role: 0 | 1 | 2,
   owner_name: string;
   member_count: number
}

interface Admin extends BaseUser  {
    role: 1 | 2
    code: string
}

interface RegularUser extends BaseUser {
   role: 0
}

type CourseGeneral = Admin | RegularUser

type BaseUser = {
   id: number
   name: string;
   role: 0 | 1 | 2,
   owner_name: string;
   member_count: number
}

interface Admin extends BaseUser  {
    role: 1 | 2
    code: string
}

interface RegularUser extends BaseUser {
   role: 0
}

type CourseGeneral = Admin | RegularUser

you could also do

type BaseUser = {
   id: number
   name: string;
   role: 0 | 1 | 2,
   owner_name: string;
   member_count: number
}

type Admin  = BaseUser & {
    role: 1 | 2
    code: string
}

type RegularUser = BaseUser & {
   role: 0
}

type CourseGeneral = Admin | RegularUser

type BaseUser = {
   id: number
   name: string;
   role: 0 | 1 | 2,
   owner_name: string;
   member_count: number
}

type Admin  = BaseUser & {
    role: 1 | 2
    code: string
}

type RegularUser = BaseUser & {
   role: 0
}

type CourseGeneral = Admin | RegularUser

I like the code style of version 2 more, but I think the type inference is a little better with the interfaces don't quote me on that though haha

Perfect•2y ago

Awesome, I will try these out, much appreciated! I am basically only gonna show the code to roles 1 and 2 so needed a type to express that Seems this will work great And the data fetch could be either ^

ippo•2y ago

or something like this:

type CourseGeneralBase = {
  id: number;
  name: string;
  owner_name: string;
  member_count: number;
}

type CourseGeneral =
    CourseGeneralBase & { code: string; role: 1 | 2; } |
    CourseGeneralBase & { role: 0; };

type CourseGeneralBase = {
  id: number;
  name: string;
  owner_name: string;
  member_count: number;
}

type CourseGeneral =
    CourseGeneralBase & { code: string; role: 1 | 2; } |
    CourseGeneralBase & { role: 0; };

Perfect•2y ago

When I am doing it any of these ways, one of my components that could possibly render a code (if role is 1 or 2) is giving me this error.

Perfect•2y ago

Now I understand its trying to say its not guaranteed to exist, its basically an optional prop. Do i have to make a new type for this

Perfect•2y ago

Perfect•2y ago

Ah damn hold on ignore this I gotta change some stuff I am all over the place

ippo•2y ago

@Perfect check this out https://www.typescriptlang.org/play?#code/C4TwDgpgBAwg9gVwE4GcIHEIDsJIIYA2AQnmlALxQDeAUFFAJYAmAXFFggLYBGuA3HXZ5OENimBIGWAOYD6cAO44kAfSzDRUcZJlyoInrhUBjRFmBsOhpAIC+NGqEixEqDNlyEKg+vGRpMZUISMgAyaihTJk1tKVkoJDgCTQBGKAAfKAAmPihbDJ8Xf3cg4lJocKoEpM0ABlzbAQdTLHEitxg8JDY-N0DPAgpqQWY2FIAaQXURNgAiIjhuWcn5JSNpzVmABQhgXGXBA15VUwRzNgAWLJXIuGi5gFkATRUYAHkAEQBRA-pE5LYWXoAHpgVAAEpfLYAGQAgjAvlAACoACQAkgBlKAAdTRqKgAH4oHgsEwoCBEFAFAwCIM0NAWABKGiNBxAA

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Perfect•2y ago

What am I replacing exactly? do you mean change to 0?

Perfect•2y ago

Adding this fixed it for now 🙂 - just saying that code is potentially not going to be a prop

Perfect•2y ago

But then here, TS not saying code doesnt exist if role === 0

ippo•2y ago

if I use role: 0, it is telling me that code: should not be there

Perfect•2y ago

Hmmm Well, dont feel like you have to read all this but this is my flow

type CourseGeneralBase = {
  id: number;
  name: string;
  owner_name: string;
  member_count: number;
};

type CourseGeneral =
  | (CourseGeneralBase & { code: string; role: 1 | 2 })
  | (CourseGeneralBase & { role: 0 });

// saying that data will be a CourseGeneral array
const { data, error, loading } = useClerkSWR<CourseGeneral[]>("/courses");

// filtering the array using my own function to avoid two calls to filter
  const [ownedCourses, joinedCourses] = doubleFilter(
    data,
    (course) => course.role === 2
  );

              <Tab.Panel>
                {ownedCourses.length === 0 && (
                  <p>You have not created any courses</p>
                )}
                {ownedCourses.map((curr) => (
                  <CourseCard key={curr.id} {...curr} />
                ))}
              </Tab.Panel>
              <Tab.Panel>
                {joinedCourses.length === 0 && (
                  <p>You have not joined any courses</p>
                )}
                {joinedCourses.map((curr) => (
                  <CourseCard key={curr.id} {...curr} />
                ))}
              </Tab.Panel>

// then this is the component prop types I am using ^
const CourseCard = ({
  id,
  name,
  role,
  code,
  owner_name,
  member_count,
}: CourseGeneral)
//rest of component

type CourseGeneralBase = {
  id: number;
  name: string;
  owner_name: string;
  member_count: number;
};

type CourseGeneral =
  | (CourseGeneralBase & { code: string; role: 1 | 2 })
  | (CourseGeneralBase & { role: 0 });

// saying that data will be a CourseGeneral array
const { data, error, loading } = useClerkSWR<CourseGeneral[]>("/courses");

// filtering the array using my own function to avoid two calls to filter
  const [ownedCourses, joinedCourses] = doubleFilter(
    data,
    (course) => course.role === 2
  );

              <Tab.Panel>
                {ownedCourses.length === 0 && (
                  <p>You have not created any courses</p>
                )}
                {ownedCourses.map((curr) => (
                  <CourseCard key={curr.id} {...curr} />
                ))}
              </Tab.Panel>
              <Tab.Panel>
                {joinedCourses.length === 0 && (
                  <p>You have not joined any courses</p>
                )}
                {joinedCourses.map((curr) => (
                  <CourseCard key={curr.id} {...curr} />
                ))}
              </Tab.Panel>

// then this is the component prop types I am using ^
const CourseCard = ({
  id,
  name,
  role,
  code,
  owner_name,
  member_count,
}: CourseGeneral)
//rest of component

I think it may have to do with the rest props, but TS is not wrong. the code prop will not always be sent because it may not even exist

ippo•2y ago

I derived the types of your optional type that you pasted above just in case:, write it like this (use eslint with airbnb rules (write variable names small)

const courseCard: CourseGeneral = ({ ...

const courseCard: CourseGeneral = ({ ...

Perfect•2y ago

courseCard is a component, shouldn't that be in caps?

ippo•2y ago

ahh okay, didn't know that it is a react component 🙂

Perfect•2y ago

Yeah sorry here it is

const CourseCard = ({
  id,
  name,
  role,
  code, // ERROR - Property 'code' does not exist on type 'CourseGeneral'.
  owner_name,
  member_count,
}: CourseGeneral & { code?: string }) => {
  return (
    <Link
      href={`/courses/${id}`}
    >
      <p >{owner_name}</p>
      <h3>{name}</h3>
      <div>
        <div>
          <UserIcon />
          <p>
            {member_count} {member_count === 1 ? "Member" : "Members"}
          </p>
        </div>
        {role === 2 || role === 1 ? (
          <div >
            <KeyIcon  />
            <p>{code}</p>
          </div>
        ) : null}
      </div>
    </Link>
  );
};

const CourseCard = ({
  id,
  name,
  role,
  code, // ERROR - Property 'code' does not exist on type 'CourseGeneral'.
  owner_name,
  member_count,
}: CourseGeneral & { code?: string }) => {
  return (
    <Link
      href={`/courses/${id}`}
    >
      <p >{owner_name}</p>
      <h3>{name}</h3>
      <div>
        <div>
          <UserIcon />
          <p>
            {member_count} {member_count === 1 ? "Member" : "Members"}
          </p>
        </div>
        {role === 2 || role === 1 ? (
          <div >
            <KeyIcon  />
            <p>{code}</p>
          </div>
        ) : null}
      </div>
    </Link>
  );
};

I guess for now I am just gonna add that extra optional part and manually check the role being 2 or 1 to display code or in turn, I know code will only be a string (not undefined) if role is 2 or 1 so I can just display code whenever it exists

Sybatron•2y ago

that's because of the type narowing you need some prop like role to identify which of the 2 cases you want you need some conditional to check if role !== 0 then you try to use .code otherwise you get error

Jon Higger (He / Him)•2y ago

You won’t be able to destructure the code field with this setup because now it may not be there in the args. But if you make it one object like “courseGeneral” then you can say “if the courseGenerals code is 1 or 2 then pull off the code field” and then typescript will be happy. This is actually an example of typescript doing something you want it to. You don’t want to accidentally call on the code field when it’s not there

Perfect•2y ago

@Sybatron @Jon Higger (He / Him) thanks guys! This solves it 🙏

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More Elegant Way For Type