Redux-SessionStorage-Simple

The same library as by Frank Kilkelly, but for sessionStorage instead of localStorage.

Save and load Redux state to and from SessionStorage.

Installation

npm install --save redux-sessionstorage-simple

Usage Example (ES6 code)

import { applyMiddleware, createStore } from "redux"
import reducer from "./reducer"

// Import the necessary methods for saving and loading
import { save, load } from "redux-sessionstorage-simple"

/*
    Saving to SessionStorage is achieved using Redux 
    middleware. The 'save' method is called by Redux 
    each time an action is handled by your reducer.
*/    
const createStoreWithMiddleware 
    = applyMiddleware(
        save() // Saving done here
    )(createStore)
    
/*
    Loading from SessionStorage happens during
    creation of the Redux store.
*/  
const store = createStoreWithMiddleware(
    reducer,    
    load() // Loading done here
)    

API

save([Object config])

Saving to SessionStorage is achieved using Redux middleware and saves each time an action is handled by your reducer. You will need to pass the save method into Redux's applyMiddleware method, like so...

applyMiddleware(save())

See the Usage Example above to get a better idea of how this works.

Arguments

The save method takes a optional configuration object as an argument. It has the following properties:

{
    [Array states],
    [Array ignoreStates]
    [String namespace],
    [String namespaceSeparator],
    [Number debounce],
    [Boolean disableWarnings]
}

• states (Array, optional) - This is an optional array of strings specifying which parts of the Redux state tree you want to save to SessionStorage. e.g. ["user", "products"]. Typically states have identical names to your Redux reducers. If you do not specify any states then your entire Redux state tree will be saved to SessionStorage.
• ignoreStates (Array, optional) - This is an optional array of strings specifying which parts of the Redux state tree you do not want to save to SessionStorage i.e. ignore. e.g. ["miscUselessInfo1", "miscUselessInfo2"]. Typically states have identical names to your Redux reducers. Unlike the states property, ignoreStates only works on top-level properties within your state, not nested state as shown in the Advanced Usage section below e.g. "miscUselessInfo1" = works, "miscUselessInfo1.innerInfo" = doesn't work.
• namespace (String, optional) - This is an optional string specifying the namespace to add to your SessionStorage items. For example if you have a part of your Redux state tree called "user" and you specify the namespace "my_cool_app", it will be saved to SessionStorage as "my_cool_app_user"
• namespaceSeparator (String, optional) - This is an optional string specifying the separator used between the namespace and the state keys. For example with the namespaceSeparator set to "::", the key saved to the SessionStorage would be "my_cool_app::user"
• debounce (Number, optional) - Debouncing period (in milliseconds) to wait before saving to SessionStorage. Use this as a performance optimization if you feel you are saving to SessionStorage too often. Recommended value: 500 - 1000 milliseconds
• disableWarnings (Boolean, optional) - Any exceptions thrown by SessionStorage will be logged as warnings in the JavaScript console by default, but can be silenced by setting disableWarnings to true.

Examples

Save entire state tree - EASIEST OPTION.

save()

Save specific parts of the state tree.

save({ states: ["user", "products"] })

Save entire state tree except the states you want to ignore.

save({ ignoreStates: ["miscUselessInfo1", "miscUselessInfo2"] })

Save the entire state tree under the namespace "my_cool_app". The key "my_cool_app" will appear in SessionStorage.

save({ namespace: "my_cool_app" })

Save the entire state tree only after a debouncing period of 500 milliseconds has elapsed

save({ debounce: 500 })

Save specific parts of the state tree with the namespace "my_cool_app". The keys "my_cool_app_user" and "my_cool_app_products" will appear in SessionStorage.

save({
    states: ["user", "products"],
    namespace: "my_cool_app"
})

Save specific parts of the state tree with the namespace "my_cool_app" and the namespace separator "::". The keys "my_cool_app::user" and "my_cool_app::products" will appear in SessionStorage.

save({
    states: ["user", "products"],
    namespace: "my_cool_app",
    namespaceSeparator: "::"
})

load([Object config])

Loading Redux state from SessionStorage happens during creation of the Redux store.

createStore(reducer, load())    

See the Usage Example above to get a better idea of how this works.

Arguments

The load method takes a optional configuration object as an argument. It has the following properties:

{
    [Array states],    
    [String namespace],
    [String namespaceSeparator],
    [Object preloadedState],
    [Boolean disableWarnings]
}

• states (Array, optional) - This is an optional array of strings specifying which parts of the Redux state tree you want to load from SessionStorage. e.g. ["user", "products"]. These parts of the state tree must have been previously saved using the save method. Typically states have identical names to your Redux reducers. If you do not specify any states then your entire Redux state tree will be loaded from SessionStorage.
• namespace (String, optional) - If you have saved your entire state tree or parts of your state tree with a namespace you will need to specify it in order to load it from SessionStorage.
• namespaceSeparator (String, optional) - If you have saved entire state tree or parts of your state tree with a namespaceSeparator, you will need to specify it in order to load it from SessionStorage.
• preloadedState (Object, optional) - Passthrough for the preloadedState argument in Redux's createStore method. See section Advanced Usage below.
• disableWarnings (Boolean, optional) - When you first try to a load a state from SessionStorage you will see a warning in the JavaScript console informing you that this state load is invalid. This is because the save method hasn't been called yet and this state has yet to been written to SessionStorage. You may not care to see this warning so to disable it set disableWarnings to true. Any exceptions thrown by SessionStorage will also be logged as warnings by default, but can be silenced by setting disableWarnings to true.

Examples

Load entire state tree - EASIEST OPTION.

load()

Load specific parts of the state tree.

load({ states: ["user", "products"] })

Load the entire state tree which was previously saved with the namespace "my_cool_app".

load({ namespace: "my_cool_app" })

Load specific parts of the state tree which was previously saved with the namespace "my_cool_app".

load({ 
    states: ["user", "products"],
    namespace: "my_cool_app"
})

Load specific parts of the state tree which was previously saved with the namespace "my_cool_app" and namespace separator "::".

load({ 
    states: ["user", "products"],
    namespace: "my_cool_app",
    namespaceSeparator: "::"
})

combineLoads(...loads)

If you provided more than one call to save in your Redux middleware you will need to use combineLoads for a more intricate loading process.

Arguments

• loads - This method takes any number of load methods as arguments, with each load handling a different part of the state tree. In practice you will provide one load method to handle each save method provided in your Redux middleware.

Example

Load parts of the state tree saved with different namespaces. Here are the save methods in your Redux middleware:

applyMiddleware(
    save({ states: ["user"], namespace: "account_stuff" }),
    save({ states: ["products", "categories"], namespace: "site_stuff" })
)

The corresponding use of combineLoads looks like this:

combineLoads( 
    load({ states: ["user"], namespace: "account_stuff" }),
    load({ states: ["products", "categories"], namespace: "site_stuff" })
)

clear([Object config])

Clears all Redux state tree data from SessionStorage. Note: only clears data which was saved using this module's functionality

Arguments

The clear method takes a optional configuration object as an argument. It has the following properties:

{
    [String namespace],
    [Boolean disableWarnings]
}

• namespace - If you have saved your entire state tree or parts of your state tree under a namespace you will need to specify it in order to clear that data from SessionStorage.
• disableWarnings (Boolean, optional) - Any exceptions thrown by SessionStorage will be logged as warnings in the JavaScript console by default, but can be silenced by setting disableWarnings to true.

Examples

Clear all Redux state tree data saved without a namespace.

clear()

Clear Redux state tree data saved with a namespace.

clear({
    namespace: "my_cool_app"
})  

Advanced Usage

In a more complex project you may find that you are saving unnecessary reducer data to SessionStorage and would appreciate a more granular approach. Thankfully there is a way to do this.

First let's look at a normal example. Let's say you have a reducer called settings and its state tree looks like this:

const settingsReducerInitialState = {
    theme: 'light',
    itemsPerPage: 10
}

Using redux-sessionstorage-simple's save() method for the settings reducer would look like this:

save({ states: ["settings"] })

This saves all of the settings reducer's properties to SessionStorage. But wait, what if we really only care about saving the user's choice of theme and not itemsPerPage. Here's how to fix this:

save({ states: ["settings.theme"] })

This saves only the theme setting to SessionStorage. However this presents an additional problem, if itemsPerPage is not saved won't my app crash when it can't find it upon loading from SessionStorage?

Yes in most cases it would. So to prevent this you can use the preloadedState argument in the load() method to provide some initial data.

load({
    states: ["settings.theme"],
    preloadedState: {
        itemsPerPage: 10        
    }
})

Also note in the above example that since settings.theme was specified in the load() method we must also mirror this exactly in the save() method. This goes for all states you specify using the granular approach.

So if you have:

save({ states: ["settings.theme"] })

You must also have:

load({ states: ["settings.theme"] })

Testing

To run tests for this package open the file 'test/test.html' in your browser. Because this package uses SessionStorage we therefore need to test it in an environment which supports it i.e. modern browsers.

Removal of support for Immutable.js data structures

Support for Immutable.js data structures has been removed as of version 1.4.0. If you require this functionality please install version 1.4.0 using the following command:

npm install --save [email protected]

Feedback

Pull requests and opened issues are welcome!

License

MIT