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Handle rejections in migration actions #148

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Jan 11, 2018
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Handle rejections in migration actions #148

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4 changes: 2 additions & 2 deletions lib/migration.js
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Original file line number Diff line number Diff line change
Expand Up @@ -41,14 +41,14 @@ class Migration {
}

_apply(action, pgm) {
return new Promise((resolve) => {
return new Promise((resolve, reject) => {
if (action.length === 2) {
action(pgm, resolve);
} else {
const result = action(pgm);
// result conforms to Promises/A+ spec
if (typeof result === 'object' && typeof result.then === 'function') {
result.then(resolve);
result.then(resolve).catch(err => reject(err));
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Thanks for contributing!
I would prefer .catch(reject)

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It's not the same thing!

In fact if you .catch(reject) the error isn't passed to the reject call and thus you won't get the error message for the rejection.

Instead if you do .catch(err => reject(err)) you pass the error and when the rejection is handled it will print out the error message to the user.

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It is almost the same thing as .catch(reject) is equivalent to .catch((...args) => reject(...args))

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Try the difference in your code

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Tried and got same result

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Promise.reject(new Error('fail')).catch(console.log.bind(console));
Promise.reject(new Error('fail')).catch(err => console.log(err));

have same result...

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Ok

} else {
resolve();
}
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