Flow: Property cannot be accessed on any member of intersection type intersection

[7ynk3r]

This should work

// @flow
'use strict';

type X = ({a:true} & {b:string}) | ({a:false} & {c:string});
// type X = {a:true, b:string} | {a:false, c:string}; // this works.

function hello(x:X): string{
  return x.a ? x.b : x.c;
}

This is the error

test.js:8
  8:   return x.a ? x.b : x.c;
                    ^^^ property `b`. Property cannot be accessed on any member of intersection type
  8:   return x.a ? x.b : x.c;
                    ^ intersection
  Member 1:
    4: type X = ({a:true} & {b:string}) | ({a:false} & {c:string});
                                           ^^^^^^^^^ object type
  Error:
    8:   return x.a ? x.b : x.c;
                        ^ property `b`. Property not found in
    4: type X = ({a:true} & {b:string}) | ({a:false} & {c:string});
                                           ^^^^^^^^^ object type
  Member 2:
    4: type X = ({a:true} & {b:string}) | ({a:false} & {c:string});
                                                       ^^^^^^^^^^ object type
  Error:
    8:   return x.a ? x.b : x.c;
                        ^ property `b`. Property not found in
    4: type X = ({a:true} & {b:string}) | ({a:false} & {c:string});
                                                       ^^^^^^^^^^ object type

test.js:8
  8:   return x.a ? x.b : x.c;
                          ^^^ property `c`. Property cannot be accessed on any member of intersection type
  8:   return x.a ? x.b : x.c;
                          ^ intersection
  Member 1:
    4: type X = ({a:true} & {b:string}) | ({a:false} & {c:string});
                 ^^^^^^^^ object type
  Error:
    8:   return x.a ? x.b : x.c;
                              ^ property `c`. Property not found in
    4: type X = ({a:true} & {b:string}) | ({a:false} & {c:string});
                 ^^^^^^^^ object type
  Member 2:
    4: type X = ({a:true} & {b:string}) | ({a:false} & {c:string});
                            ^^^^^^^^^^ object type
  Error:
    8:   return x.a ? x.b : x.c;
                              ^ property `c`. Property not found in
    4: type X = ({a:true} & {b:string}) | ({a:false} & {c:string});
                            ^^^^^^^^^^ object type

[nmn]

I think & doesn't quite work correctly for extending objects.

[7ynk3r]

what other alternatives can i use to extend an object?
still this is a bug. i can use & without any problem as long as i don't combine it with |

[nmn]

I can't always use & on it's own either. It works most of the times, but every now and then it just breaks down.

It tends to not work when using flow check-contents in a linter plugin

I'm trying to find workaround for now.

[avikchaudhuri]

This is going to be fixed in an upcoming release.

[chris-lock]

+1

[kevinSuttle]

@avikchaudhuri I'm still seeing this error, but I'm probably approaching the issue incorrectly. https://github.com/facebook/flow/issues/2135

[natdm]

I am still seeing this issue.

// ... generated.js

// Transaction represents a single atomic transaction in the application
export type Transaction = { 
    description: string, 
    bidder_id: number, // foreign key to bidder table

    stripe_transaction_id: string, 
    event_id: number, // foreign key to event table

    amount: number, // in cents

    fee: number, // in cents

    status: string
}

import type {
    Transaction as transaction,
} from './generated';

// merge types with this ID until Typewriter can get this from the embedded types
type ID = { ID: number };
type UpdatedAt = { UpdatedAt: string };

export type Transaction = ID & UpdatedAt & transaction;

results in: property `ID` Property cannot be accessed on mixed

[heywarddai]

+2

[natdm]

Why is this closed? I still have the same issue I posted above with .47

[ummahusla]

Still get this error. Just created a new issue.