Meta Reducers
A meta reducer is a higher order reducer that allows you to take action on the global state rather than a state slice. In NGXS, we don't have this concept but you can accomplish this with plugins.
An example of a meta reducer might be to clear the entire state when a user logs out. An example implementation would be:
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import { getActionTypeFromInstance } from '@ngxs/store';
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​
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export function logoutPlugin(state, action, next) {
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// Use the get action type helper to determine the type
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if (getActionTypeFromInstance(action) === Logout.type) {
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// if we are a logout type, lets erase all the state
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state = {};
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}
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​
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// return the next function with the empty state
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return next(state, action);
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}
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Then we import that like:
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import { NgModule } from '@angular/core';
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import { NGXS_PLUGINS } from '@ngxs/store';
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​
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@NgModule({
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imports: [NgxsModule.forRoot([])],
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providers: [
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{
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provide: NGXS_PLUGINS,
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useValue: logoutPlugin,
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multi: true
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}
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]
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})
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export class AppModule {}
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Now when we dispatch the logout action it will use our new plugin and erase the state.
Last modified 2yr ago
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