K
Kysely•7d ago
lorentz

how to union two queries with json_build_object?

i would like to union two queries to get a result of type QueryA | QueryB. this query fails the type checker but the generated query seems to work as intended. is there a type hint i can provide somehow? https://kyse.link/2TBLF
Solution:
The unioned expressions need to have the same type. You used first_name in the first one an name in the second one. If both have the same property name it works. https://kyse.link/Bc300 When you use different keys, the correct type of the JSON object would be { name: string | undefined, first_name: string | undefined } but Kysely isn't able to infer it....
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5 Replies
Solution
koskimas
koskimas•7d ago
The unioned expressions need to have the same type. You used first_name in the first one an name in the second one. If both have the same property name it works. https://kyse.link/Bc300 When you use different keys, the correct type of the JSON object would be { name: string | undefined, first_name: string | undefined } but Kysely isn't able to infer it.
koskimas
koskimas•7d ago
This is far from optimal, but you could use $castTo to fix the type https://kyse.link/Ppshx
lorentz
lorentz•7d ago
alright thanks. so there is no way to make kysely type the whole result to this? 
({
  id: number;
  details: {
    first_name: string;
  };
} | {
  id: number;
  details: {
    name: string;
  };
})[]
({
  id: number;
  details: {
    first_name: string;
  };
} | {
  id: number;
  details: {
    name: string;
  };
})[]
koskimas
koskimas•7d ago
No, that's not possible This is 
{
  id: number;
  details: {
    first_name: string;
  } | {
    name: string
  };
}[]
{
  id: number;
  details: {
    first_name: string;
  } | {
    name: string
  };
}[]
by just casting details to that type
lorentz
lorentz•7d ago
ah ok! 🙇 so this in full https://kyse.link/CtZGS. now i realize what i need is really a discriminated union type though, so something closer to this https://kyse.link/4Zw87. the result gets the correct type now 
const rows: ({
    id: number;
    type: "person";
    details: {
        first_name: string;
    };
} | {
    id: number;
    type: "pet";
    details: {
        name: string;
    };
})[]
const rows: ({
    id: number;
    type: "person";
    details: {
        first_name: string;
    };
} | {
    id: number;
    type: "pet";
    details: {
        name: string;
    };
})[]
but then back to Types of property 'details' are incompatible. where union is not happy. is there any way to just convince the union that all is good? 😄 don't mind explicitly casting anything at this point ok i think i have something https://kyse.link/xpMTf. perhaps not ideal, but works. thank you very much for the help!
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