Vuex: createNamespacedHelpers with dynamic namespace - vue.js

Question

In almost all guides, tutorial, posts, etc that I have seen on vuex module registration, if the module is registered by the component the createNamespacedHelpers are imported and defined prior to the export default component statement, e.g.:
import {createNamespacedHelpers} from 'vuex'
const {mapState} = createNamespacedHelpers('mymod')
import module from '#/store/modules/mymod'
export default {
beforeCreated() {
this.$store.registerModule('mymod', module)
}
}
this works as expected, but what if we want the module to have a unique or user defined namespace?
import {createNamespacedHelpers} from 'vuex'
import module from '#/store/modules/mymod'
export default {
props: { namespace: 'mymod' },
beforeCreated() {
const ns = this.$options.propData.namespace
this.$store.registerModule(ns, module)
const {mapState} = createNamespacedHelpers(ns)
this.$options.computed = {
...mapState(['testVar'])
}
}
}
I thought this would work, but it doesnt.
Why is something like this needed?
because
export default {
...
computed: {
...mapState(this.namespace, ['testVar']),
...
},
...
}
doesnt work

Answer 1

This style of work around by utilising beforeCreate to access the variables you want should work, I did this from the props passed into your component instance:
import { createNamespacedHelpers } from "vuex";
import module from '#/store/modules/mymod';
export default {
name: "someComponent",
props: ['namespace'],
beforeCreate() {
let namespace = this.$options.propsData.namespace;
const { mapActions, mapState } = createNamespacedHelpers(namespace);
// register your module first
this.$store.registerModule(namespace, module);
// now that createNamespacedHelpers can use props we can now use neater mapping
this.$options.computed = {
...mapState({
name: state => state.name,
description: state => state.description
}),
// because we use spread operator above we can still add component specifics
aFunctionComputed(){ return this.name + "functions";},
anArrowComputed: () => `${this.name}arrows`,
};
// set up your method bindings via the $options variable
this.$options.methods = {
...mapActions(["initialiseModuleData"])
};
},
created() {
// call your actions passing your payloads in the first param if you need
this.initialiseModuleData({ id: 123, name: "Tom" });
}
}
I personally use a helper function in the module I'm importing to get a namespace, so if I hadmy module storing projects and passed a projectId of 123 to my component/page using router and/or props it would look like this:
import projectModule from '#/store/project.module';
export default{
props['projectId'], // eg. 123
...
beforeCreate() {
// dynamic namespace built using whatever module you want:
let namespace = projectModule.buildNamespace(this.$options.propsData.projectId); // 'project:123'
// ... everything else as above
}
}
Hope you find this useful.

Answer 2

All posted answers are just workarounds leading to a code that feels verbose and way away from standard code people are used to when dealing with stores.
So I just wanted to let everyone know that brophdawg11 (one of the commenters on the issue #863) created (and open sourced) set of mapInstanceXXX helpers aiming to solve this issue.
There is also series of 3 blog posts explaining reasons behind. Good read...

Answer 3

I found this from veux github issue, it seems to meet your needs
https://github.com/vuejs/vuex/issues/863#issuecomment-329510765
{
props: ['namespace'],
computed: mapState({
state (state) {
return state[this.namespace]
},
someGetter (state, getters) {
return getters[this.namespace + '/someGetter']
}
}),
methods: {
...mapActions({
someAction (dispatch, payload) {
return dispatch(this.namespace + '/someAction', payload)
}
}),
...mapMutations({
someMutation (commit, payload) {
return commit(this.namespace + '/someMutation', payload)
})
})
}
}
... or maybe we don't need mapXXX helpers,
mentioned by this comment https://github.com/vuejs/vuex/issues/863#issuecomment-439039257
computed: {
state () {
return this.$store.state[this.namespace]
},
someGetter () {
return this.$store.getters[this.namespace + '/someGetter']
}
},