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Updated Design: Persistable Context (markdown)

Hiroki Uchikawa 2018-03-30 18:14:42 +09:00
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Design:-Persistable-Context.md

@ -269,19 +269,27 @@ My proposal is as follows. Do you agree with this option?
#### How to get keys in the external storage
In [Usage](#usage),
> If you want to access the external storage, add the prefix(*) to the key of context data as follows.
Currently,`keys()` needs no arguments.
How we get all keys in the external storage?
Currently,`keys()` needs no arguments. How we get all keys in the external storage?
1. Adding a parameter to `keys()`
`keys("$identifier")` returns all keys in the specified storage.
If `$identifier` is `null` or `undefined`, `keys()` return all keys in the memory context.
If a user uses a LocalFileSystem plugin as `$file`, `keys("$file")` returns all keys in the LocalFileSystem context.
If you use a LocalFileSystem plugin as `$file`, `keys("$file")` returns all keys in the LocalFileSystem context.
* Pros: You can get keys from the specified storage. You can also get keys from the memory context in the same way as current. i.e. `flow.keys()`
* Cons: `keys()` usage changes.
2. No arguments same as current
a. `keys()` returns all keys in all external storage.
If a user uses a LocalFileSystem plugin, `keys()` returns all keys in the memory and LocalFileSystem context.
If you use a LocalFileSystem plugin, `keys()` returns all keys in the memory and LocalFileSystem context.
If this is chosen, we have to discuss about returned keys format.
* Pros: You can use `keys()` with no arguments as before.
* Cons: You cannot get keys from the specified storage.
b. `keys()` returns all keys in the memory context.
Node-RED don't provide the interface of `keys` to plugin. So a user cannot get all keys by `keys()`.
If a plugin wants to returns keys, it will use `run()` to return keys.
Node-RED don't provide the interface of `keys` to plugin. So you cannot get all keys by `keys()`.
If a plugin wants to returns keys, it will use `run()` to return keys.
* Pros: You can use `keys()` with no arguments as before.
* Cons: You cannot get keys from the external storage by `keys()`
> HU: I prefer number 1. I think that the cons is small impact same as set/get.