Versioned storage with migrations #49

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opened 2015-11-22 20:31:08 +00:00 by steida · 6 comments

steida commented

2015-11-22 20:31:08 +00:00

(Migrated from github.com)

Hi,

I am just curious if you thought about store migrations? What if we change structure? I think it should be responsibility of every reducer reviver.

Hi, I am just curious if you thought about store migrations? What if we change structure? I think it should be responsibility of every reducer reviver.

michaelcontento commented

2015-11-23 07:54:58 +00:00

(Migrated from github.com)

Hi,

currently there is no built-in functionality to handle migrations at all. But it should be pretty easy to create a custom engine decorator for this purpose. Here is a short (untested!) draft:

// The engine as you like
import createEngine from 'redux-storage/engines/reactNativeAsyncStorage';
let engine = createEngine('my-save-key');

// Now add the new migrations decorator
import migrationDecorator from './migrationDecorator';
engine = migrationDecorator(engine, 'v3');
engine.addMigration('v1', (state) => { /* migration step for v1 */ return state; });
engine.addMigration('v2', (state) => { /* migration step for v2 */ return state; });
engine.addMigration('v3', (state) => { /* migration step for v3 */ return state; });

All you have to do in the migrationDecorator is to ....

store the current version (second argument to migrationDecorator) in the state tree on save()
compare the current version with the loaded one on load()
apply all required migration callbacks

So for the example in the draft above: if the current version is v3 and the loaded one is v1, we need to apply callbacks for v2 and v3.

Is this a good starting point for you?

Feel free to submit such a decorator as a PR! I'm thankful for every contribution :)

Hi, currently there is no built-in functionality to handle migrations at all. But it should be pretty easy to create a custom engine decorator for this purpose. Here is a short (untested!) draft: ``` js // The engine as you like import createEngine from 'redux-storage/engines/reactNativeAsyncStorage'; let engine = createEngine('my-save-key'); // Now add the new migrations decorator import migrationDecorator from './migrationDecorator'; engine = migrationDecorator(engine, 'v3'); engine.addMigration('v1', (state) => { /* migration step for v1 */ return state; }); engine.addMigration('v2', (state) => { /* migration step for v2 */ return state; }); engine.addMigration('v3', (state) => { /* migration step for v3 */ return state; }); ``` All you have to do in the `migrationDecorator` is to .... - store the current version (second argument to `migrationDecorator`) in the state tree on `save()` - compare the current version with the loaded one on `load()` - apply all required migration callbacks So for the example in the draft above: if the current version is `v3` and the loaded one is `v1`, we need to apply callbacks for `v2` and `v3`. Is this a good starting point for you? Feel free to submit such a decorator as a PR! I'm thankful for every contribution :)

steida commented

2015-11-23 17:15:55 +00:00

(Migrated from github.com)

Awesome answer, thank you! Once I will implemented it, I will send you a PR.

michaelcontento commented

2015-11-23 18:37:38 +00:00

(Migrated from github.com)

Thanks! I'll close this issue for now :)

steida commented

2015-11-30 04:47:25 +00:00

(Migrated from github.com)

Here is it: https://gist.github.com/steida/f5e53c69c4e3b423c15d

I simplified api, and I don't think we need explicit current version, since it's defined by migrations array.

Unfortunately, because cognitive overhead, I'm not able to send PR for

indent_size = 4
indent_style = space

Two spaces ftw.

Here is it: https://gist.github.com/steida/f5e53c69c4e3b423c15d I simplified api, and I don't think we need explicit current version, since it's defined by migrations array. Unfortunately, because `cognitive overhead`, I'm not able to send PR for ``` indent_size = 4 indent_style = space ``` Two spaces ftw.

michaelcontento commented

2016-01-26 08:15:43 +00:00

(Migrated from github.com)

Re-opened as a reminder. If someone want to contribute @steida's gist as a PR, I'd be very happy 😃

Re-opened as a reminder. If someone want to contribute @steida's gist as a PR, I'd be very happy :smiley:

steida commented

2016-01-26 15:26:11 +00:00

(Migrated from github.com)

That's what I am using https://gist.github.com/steida/85443aac1dcb6daaa245 No time to send PR yet, maybe later :-)

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