Firebase Cloud Functions Object possibly 'undefined'

Question

I have the following code in typescript and i get this error on the line: change.after.data();, Object is posibbly \'undefined\':

import * as functi         


        

Answer 1

If you look at the types for the onUpdate handler, the argument for change has 2 optional properties, after and before:

class Change {
    before?: T;
    after?: T;
    constructor(before?: T, after?: T);
}

Because you want to access after, you'll need to wrap it in a conditional, something like this following:

functions.firestore.document("Settings/ShiftsEditMode").onUpdate(change=> {
    if (change.after) {
        const after = change.after.data();
        ...
    }
}