json valueEncoding doesn't work as expected

[huan]

I use json valueEncoding for v1 and it works without any problem.

After upgrade to v2, It does not work anymore: after putting an object to leveldb, we will get back a [object Object] value of string type.

The following code can be able to reproduce the problem:

import * as encoding   from 'encoding-down'
import * as leveldown  from 'leveldown'
import * as levelup    from 'levelup'

async function main() {
  const encoded = encoding(leveldown('/tmp/test'), {
    valueEncoding: 'json',
  })
  const levelDb = levelup(encoded)

  await levelDb.put('test', {a: 1})
  const value = await levelDb.get('test')

  console.log('value type:', typeof value)  // value type: string
  console.log('value:', value) // value: [object Object]
}

main()

"dependencies": {
    "encoding-down": "^2.2.1",
    "leveldown": "^1.8.0",
    "levelup": "^2.0.0-rc3",
}

After a little digging, I found the following code in AbstractLevelDOWN, which is just String(value) for the value.

AbstractLevelDOWN.prototype._serializeValue = function (value) {
  if (value == null) return ''
  return this._isBuffer(value) || process.browser ? value : String(value)
}

I have no idea how to fix it because there's too many modules/layers.

[ralphtheninja]

Thanks for reporting this. We are aware of it. But nice to have a separate issue for it :)

[ralphtheninja]

Will fix this today or tomorrow. After that I think we should release 2.0.0.

[huan]

Great to hear that, awesome!

[huan]

Looking forward to the release 2.0.0...

It seems that my build will not succeed until v2.0.0 is published...

> flash-store@0.0.14 dist:es6to5 /home/zixia/git/flash-store
> tsc --out ./bundles/flash-store.umd.js --target es5 --allowJs bundles/flash-store.es6.umd.js --lib es6,dom

node_modules/levelup/lib/levelup.d.ts(113,16): error TS2694: Namespace '"/home/zixia/git/flash-store/node_modules/abstract-leveldown/index"' has no exported member 'LevelDOWN'.
node_modules/levelup/lib/levelup.d.ts(127,16): error TS2694: Namespace '"/home/zixia/git/flash-store/node_modules/abstract-leveldown/index"' has no exported member 'LevelDOWN'.

My current dependence version:

   "encoding-down": "^2.3.1",
   "leveldown": "^2.0.0",
   "levelup": "^2.0.0-rc3",

[ralphtheninja]

@zixia Mind trying this out again? deferred-leveldown was recently updated to take care of this.

[huan]

It seems still have problems.

I'm using the following dependences:

    "encoding-down": "^2.3.1",
    "leveldown": "^2.0.0",
    "levelup": "MeirionHughes/levelup",

After rm -fr node_modules && npm i, I ran the follow code to reproduce the problem:

import encoding   from 'encoding-down'
import leveldown  from 'leveldown'
import levelup    from 'levelup'

async function main() {
  const encoded = encoding(leveldown('/tmp/test'), {
    valueEncoding: 'json',
  })
  const levelDb = levelup(encoded)

  await levelDb.put('test', {a: 1})
  const value = await levelDb.get('test')

  console.log('value type:', typeof value)  // value type: string
  console.log('value:', value) // value: [object Object]
}

main()

Output:

$ ts-node t.ts
value type: string
value: [object Object]

The value type should be 'object'

[vweevers]

@zixia I ran your example in node (with levelup 2.0.0-rc3), got:

$ node index.js
value type: object
value: { a: 1 }

[vweevers]

Cannot reproduce with TS either. Seems to work fine here, and fails as expected if I downgrade deferred-leveldown to 2.0.0 2.0.1.

[huan]

@vweevers I had tried again, but I still ran into the same buggy result.

I had pushed my configuration & source code at here: huan/flash-store@abfb02b

Travis CI result(failed) at here: https://travis-ci.org/zixia/flash-store/jobs/284564104#L762

    operator: equal
    expected: 'object'
    actual:   'string'
    at: Object.<anonymous> (/home/travis/build/zixia/flash-store/src/flash-store.spec.ts:154:5)

[vweevers]

@zixia from the travis logs, seems it didn't install the latest deferred-leveldown:

levelup@2.0.0-rc3 (github:MeirionHughes/levelup#28131b7ffbf4834010833e06c42b4e9f55fca317)
│ ├─┬ deferred-leveldown@2.0.1

[huan]

@vweevers Yes, you are right. After installing the deferred-leveldown@2.0.2, the test passed!

# levelup json bug
ok 19 value type should be object
ok 20 should get back the original object

Sorry for misreporting because I was thought the leveldown had already linked the latest version of it.

[vweevers]

I'm not sure how the latest npm dedupes, we might need to depend on deferred-leveldown: ~2.0.2 instead of deferred-leveldown: ~2.0.0 to make sure it's installed. @ralphtheninja?

[ralphtheninja]

@vweevers It can't hurt :)

[MeirionHughes]

if @zixia is using yarn or npm 5, there will be a lockfile; I imagine it won't bump up versions unless you explicitly do so, or something depends on a specific patch version minimum.

[vweevers]

right. damn lockfiles :)

[ralphtheninja]

Maybe we should add tests for this.

[vweevers]

To levelup you mean? +1

[ralphtheninja]

Yes

[huan]

There might have other problems with the version dependencies because I'm not using package-lock.json: I hate it and had already added it to the .gitignore.

+1 for unit test, and I'd like to suggest that we also add a TypeScript unit test in level* to make sure the typing is not broken.

[vweevers]

I hate it

😁

and I'd like to suggest that we also add a TypeScript unit test in level* to make sure the typing is not broken.

Broken in what way?

[huan]

It's just my 2 cents. I think if we could have a repository that integrated with all the level-* modules and have a build/test script automatically run by CI, after enabled greenkeeper auto update, it might be able to help us to monitor the comparable status of every module update on NPM. :)

[ralphtheninja]

Tests for this added in #508