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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 #### How to get keys in the external storage
In [Usage](#usage), In [Usage](#usage),
> If you want to access the external storage, add the prefix(*) to the key of context data as follows. > 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()` 1. Adding a parameter to `keys()`
`keys("$identifier")` returns all keys in the specified storage. `keys("$identifier")` returns all keys in the specified storage.
If `$identifier` is `null` or `undefined`, `keys()` return all keys in the memory context. If `$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 2. No arguments same as current
a. `keys()` returns all keys in all external storage. 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. 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. 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()`. 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. 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.