feat: map method with default _map fallback #376
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this needs more tests to confirm _map is working properly |
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seems not all tests are ran within abstract-down's test script - I've added a test into self.js now to check the default loop-get fallback. Not sure how to make sure the |
| @@ -427,6 +435,14 @@ Delete an entry. There are no default options but `options` will always be an ob | |||
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| The default `_del()` invokes `callback` on a next tick. It must be overridden. | |||
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| ### `db._map(keys, options, callback)` | |||
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| Map each `key` in the `keys` array to a `value`. The `options` object will always have the following properties: `asBuffer`. If _any_ key in `keys` does not exist, call the `callback` function with a `new Error('NotFound')`. Otherwise call `callback` with `null` as the first argument and the values array as the second. | |||
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If any key in
keysdoes not exist, call thecallbackfunction with anew Error('NotFound')
Not sure this is desirable. You wouldn't know which key wasn't found. With parallel writes, it's not unlikely that keys will contain deleted keys.
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I'll remove the default fallback - but how would you want to deal with this? if it fails on the n'th item, then return an array with n-1 items and a non-null error?
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I was thinking that we could yield an undefined value. For example, given keys ['a', 'b', 'c'] and key b does not exist, the result would be [value, undefined, value].
| throw new Error('map() requires a callback argument') | ||
| } | ||
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| if (Array.isArray(keys) === false || keys === null) { |
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| if (Array.isArray(keys) === false || keys === null) { | |
| if (!Array.isArray(keys)) { |
The null-check is redundant.
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| const _keys = new Array(keys.length) | ||
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| for (const index in keys) { |
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| const result = new Array(count) | ||
| let index = 0 | ||
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| if (count === 0) return this._nextTick(callback, null, []) |
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Can we do this in map() instead?
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Superseded by #381 |
As per Level/community#100
Adds new
mapmethod to serve as a "multi-get" / "batch-get" method for implementing 'downs.Adds protected overload-able
_mapmethod with default fallback to looping over each key and using_get. i.e. non-breaking for non-implementing 'downs.