TypeScript: handle generated union type for relationship

Alessio 🍣

last week

9

let relationshipValue = (
  await payload.findByID({
    collection: 'sites',
    id: docId,
    depth: 0,
  })
).relationship; // string[] | MyCollection[]

if (relationshipValue.length > 0 && typeof relationshipValue[0] === 'object') {
  relationshipValue = relationshipValue.map((doc) => doc.id);
}

relationshipValue = relationshipValue as string[];

• 

  Jarrod

  Payload Team

  last week

  With depth 0 won't it always be string[]? Until we improve our internal typing to account for depth (if possible), I think you would be better off just casting right away

  
  

  
  

  let relationshipValue = (
    await payload.findByID({
      collection: 'sites',
      id: docId,
      depth: 0,
    })
  ).relationship as string[];

• 

  Alessio 🍣

  last week

  With depth 0 won't it always be string[]
  

  Hm it would, but doing

  as string[]

  just feels dirty, it gives me more responsibility to know I can't just change the depth in the future 😅 Was hoping that there is some kind of way to let typescript infer the type, so I don't have to assert the type anymore

• 

  Jarrod

  Payload Team

  last week

  So one thing you will have to be weary of, what if you get docs back with depth: 1, but one of the docs was deleted (all that is left is the ID) or you dont have access to one of the docs (you will only get the ID).

  
  

  
  

  So with that in mind, I think the safest thing to do would be to always loop, check the type of the doc when looping and return the id or the doc.id

• 

  blupandaman

  last week

  This is what I did in my project. Hard to reliably get back the Object rather than just the ID so I always type check manually to ensure I got back the right thing.

• 

  jmikrut

  Payload Team

  last week

  yes you should always manually verify the data for sure

• 

  Alessio 🍣

  last week

  ah didn't think of that either, that makes it even worse 😅

  
  
  

  I guess then this would really be the best/safest:

  
  

  let relationshipValue = (
    await payload.findByID({
      collection: 'sites',
      id: docId,
      depth: 0,
    })
  ).relationship;
  
  currentSummaries = currentSummaries.map((doc) => doc.id ?? doc) as string[];

  
  

  Although I really hate having to use

  as string[]
  
  

  Or I guess

  
  
  currentSummaries = currentSummaries.map((doc) => (doc.id as string) ?? (doc as string));
  

  is a bit nicer

  
  

  
  

  Mh found a nicer way!

  
  
  

  let relationshipValue = (
    await payload.findByID({
      collection: 'sites',
      id: docId,
      depth: 0,
    })
  ).relationship;
  
  relationshipValue = relationshipValue.map((doc: string | MyCollection) => {
    if (typeof doc === 'object') {
      return doc.id;
    } else {
      return doc;
    }
  });