I have a component that renders a table of Inventoried computer equipment. Here is the relevant code for initial render:
let oEquiptByType = reactive({
Laptop: [],
iPad: [],
"Document Camera": [],
"Overhead Projector": [],
Chromebook: [],
Desktop: [],
MacBook: [],
Scanner: [],
});
// ======== Props =========== //
const props = defineProps({
propFormData: {},
});
// Now let's use Stein to retrieve the SS data
// eslint-disable-next-line no-unused-vars
const fetchSheetsData = function () {
const store = new SteinStore(
"https://api.steinhq.com/v1/storages/618e81028d29ba2379044caa"
);
store
.read("HS - Classrooms")
.then((data) => {
scrapDataHSClassrooms.value = data;
emptyRowsRemoved.value.forEach((item) => {
// Let's construct an object that separates equipment by type
// Check if property exists on oEquiptByType object
const exists = Object.prototype.hasOwnProperty.call(
oEquiptByType,
item["Equipment"]
);
// If item(row) is good lets push the row onto the corresponding Object Array
// in oEquiptByType. This will construct an object where each object property corresponds
// to an equipment category. And each oEquiptByType entry is an array where each array
// element is a row from the SS. e.g., oEquiptByType["Laptop"][3] is a row from
// SS and is a laptop.
if (exists) {
oEquiptByType[item["Equipment"]].push(item);
}
});
})
.catch((e) => {
console.error(e);
failure.value = true;
});
};
// =============== Called on component mount =============================== //
onMounted(fetchSheetsData);
The initial render is fine. Now I have a watcher on the prop so when someone submits a new item for the inventory I push that data onto the corresponding object array (ie, a laptop would be pushed onto the oEquiptByType[props.propFormData.Equipment] via oEquiptByType[props.propFormData.Equipment].push(props.propFormData);
// ================================================================ //
// ======================= Watch effects ========================== //
// ================================================================ //
watch(props.propFormData, () => {
// Push the submitted form item onto the reactive
// oEquiptByType object array. This update of Vue state
// will then be injected into DOM and automagically update browser display.
oEquiptByType[props.propFormData.Equipment].push(props.propFormData);
});
This works fine for the first item I add to backend as you can see here with original and then adding first item :
and after first item added (a laptop)
Notice the oEquiptByType[props.propFormData.Equipment] has the new item added. Great.
But now when I add a second item (a MacBook) is added this is resulting state:
Notice the Macbook array has been updated but also the Laptop array's last item has been overwritten with the Mac book entry??? And this behavior continues for any additional items added from a user. I have read docs over and do not see anything that would explain this behavior. I'm hoping maybe someone with more than my limited experience with Vue can help me out. Any additional info needed please let me know. Thanks...
Update:
Put a JSON.Stringify in watch function
Update two:
here is lineage of prop.FormData-
we start in form-modal and emit the form data like:
emit("emiterUIUpdate", formAsPlainObject);
then catch the data in the parent App.vue:
<FormModal
v-show="isModalVisible"
#close="closeModal"
#emiterUIUpdate="updateUI"
>
<DisplayScrap :propFormData="formData" />
const formData = reactive({});
// Method to be called when there is an emiterUIUpdate event emiited
// from form-modal.vue #param(data) is the form data sent from the
// form submission via the event bus. We will then send this data back
// down to child display-scrap component via a prop.
const updateUI = (data) => {
Object.assign(formData, data);
};
and then as posted previous in display-scrap.vue the prop propFormData is defined and watched for in the watch function. hope that helps..
It seems like the watch is getting triggered more often than you expect.
Might be that changes to props.propFormData are atomic and every incremental change triggers changes to the props, which in turn triggers the watch.
Try console logging the value of props.propFormData with JSON.stringify to see what changes are triggering it.
What happens here:
Your form modal emits the emiterUIUpdate event on Ok or Save (button)
Parent takes the object emitted and use Object.assing to copy all properties of emitted object to a formData reactive object. Instead of creating completely new object, you are just replacing the values of all properties of that object all and over again
The formData object is passed by a prop to child component and whenever it changes, it is pushed to target array
As a result, you have a multiple references to same object (formData hold by a parent component) and all those references are to same object in memory. Every Object.assign will overwrite properties of this object and all references will reflect those changes (because all references are pointing to the same object in memory)
Note that this has nothing to do with Vue reactivity - this is simple JavaScript - value vs reference
There is no clear answer to what to do. There are multiple options:
Simplest (and not clearest)
just do not use Object.assign - create new object every time "Save" is clicked
change formData to a ref - const formData = ref({})
replace the value of that ref on emiterUIUpdate event - formData.value = { ...data }
your watch handler in the child will stop working because you are watching props in a wrong way - instead of watch(props.propFormData, () => { use watch(() => props.propFormData, () => {
Better solution
the data should be owned by parent component
when modal emits new data (Save), Parent will just add the newly generated object into a list
share the data with DisplayScraps component using a prop (this can be a simple list or a computed creating object similar to oEquiptByType)
Related
I'm using ngrx/component-store and loving it so far. Having prior store knowledge building my own simple ones, the only real headache I've had so far is when I've had to update an array and figured out I have to always create a new one for the internal compare() pipe to realize the array got updated.
Anyway, reading through the documentation it talks about updater methods and patchState. To me they do exactly the same thing, but their creation is slightly different. You would call patchState inside of a method while this.updater() returns a method giving you a function you can expose in your service. Anytime I'm updating my state it's always after a network call. I assume there are plenty of scenarios where you'd want to update your state without a network call so this is why you would want to have an updater available to your component to call. The question is if an updater and patchState are really doing the same thing then is it a better practice to call an updater in an effect or use patchState, or maybe am I putting too much logic in my effect?
On a side note, the docs say an updater method is supposed to be a pure function. If you're using it to your push an object onto an array then is it really pure?
// adding the selectors so people know what components are subscribing to
readonly approvals$ = this.select(state => state.requestApprovals);
readonly registration$ = this.select(state => state);
readonly updateAssessment = this.effect(($judgement: Observable<{id: string, isApproved: boolean}>) => {
return $judgement.pipe(
switchMap((evaluation) => {
const state = this.get();
return this.requestApproval.patch(state.id, state.companyName, evaluation.id, evaluation.isApproved).pipe(
tapResponse(
(result) => {
// is it better to call patchState()?
this.patchState((state) => {
for(let i = 0; i < state.requestApprovals.length; i++) {
if(state.requestApprovals[i].id == result.id) {
state.requestApprovals[i].isApproved = result.isApproved;
}
}
// the take away is you must assign a whole new array object when you update it.
state.requestApprovals = Object.assign([], state.requestApprovals);
return state;
});
// or this updater?
// this.applyDecisionPatch(evaluation);
},
// oh look! another updater reassigning my array to the state so
// it propagates to subscribers to reset the UI
() => { this.reverseDecision(); }
)
);
})
);
});
// this is private to make sure this can only be called after a network request
private readonly applyDecisionPatch = this.updater((state, value: {id: string, isApproved: boolean}) => {
for(let i = 0; i < state.requestApprovals.length; i++) {
if(state.requestApprovals[i].id == value.id) {
state.requestApprovals[i].isApproved = value.isApproved;
}
}
state.requestApprovals = Object.assign([], state.requestApprovals);
return state;
});
Note: There's no tag for ngrx-component-store so couldn't tag it.
An updater can be compared to a reducer.
All the options to modify the state should change it in an immutable way.
A library like ngrx-immer can be used to make this easier.
The main difference is that updater receives the current state, and you can change the state based on it. E.g. a conditional update, or can be used with #ngrx/entity
While with setState and patchState, you just set state properties.
setState updates the whole state object, whereas patchState only sets the given properties and doesn't touch the rest of the state object.
These two methods are also easier to use when you just want to set the state, because you don't have to create an updater function.
To answer the side question, push is not immutable. Instead of creating a new instance, it updates the array instance.
I have a component that receives data from an emit function and I wish to push object's onto an array. The trouble is when I push object onto array the object is empty?? Here is the code :
<script setup>
let formDataHistory = ref([]);
// Method to be called when there is an emiterUIUpdate event emiited
// from form-modal.vue #param(data) is the form data sent from the
// form submission via the event bus. We will then send this data back
// down to child display-scrap component via a prop.
const updateUI = (data) => {
console.log(data);
formDataHistory.value.push(data);
console.log(formDataHistory);
};
</script>
And a snapshot in devtools after pushing item onto array:
formdataHistory's first element is an empty object after the push action. Any help on proper way to mutate an array is most welcome.
Two suggestions:
Always use const on reactive variables: const formDataHistory = ref([]);. The reference itself should never change, only the value.
Try formDataHistory.value = [...formDataHistory.value, data];. It might be that refs only update if the content is replaced instead of mutated.
I want to load all the items on start without showing any message, but once after loaded. I want to capture any new row in subscriber and show it to the desktop notification.
The problem is, I'm not sure how to check if all the previous items are loaded and if the row is new item or is it from previous existing item.
this.items = this.af.database.list('notifications/'+this.uid+'/');
this.items.subscribe(list => {
list.forEach(row => {
// doing something here...
});
// once all the rows are finished loading, then any new row, show desktop notification message
});
I have user lodash for the minimal code.
// this varible holds the initial loaded keys
let loadedKeys = [];
this.items = this.af.database.list('notifications/'+this.uid+'/');
this.items.subscribe((list)=>{
// we skip it while initial load
if(!_.isEmpty(loadedKeys)){
// different is the new keys
let newKeys = _.difference(_.map(list, "$key"), loadedKeys);
if(!_.isEmpty(newKeys)){
// ... notification code here
}
}
loadedKeys = _.map(list, "$key");
});
The behave you are looking for is the default Subject approach in RxJS.
Check this reactiveX url to follow the marble diagram of Publish Subject (the equivalent for Subject in RxJS).
So you have two easy options:
1) manually index witch rows you want to display like #bash replied
2) create a Rx.Subject() and assign only the newest's rows to it. Then you subscribe to this subject in your app workflow.
The advantage of method 2 is when a new .subscribe occur, it will not retrieve previous data.
Edit: I wrote this codepen as a guide to implement your custom RxJS Subject. Hope it helps.
Assuming your rows have something unique to match with previous rows you can do the following:
// A Row item has a unique identifier id
interface Row {
id: number;
}
this.rows: Row[];
this.items$ = this.af.database.list(`notifications/${this.uid}/`).pipe(
tap(list => {
// if rows is not array, first time...
if(!Array.isArray(this.rows)) {
// first time nothing to do
return;
}
// returns true if some item from list is not found in this.rows
const foundNewRow = list.some(item => {
return ! this.rows.find(row => row.id === item.id);
});
if (foundNewRow) {
// call method to show desktop message here
}
}
);
I used a pipe and a tap operator (that you will have to import). If you subscribe to this.items$ the tap operator will do the work:
this.items$.subscribe((items => this.rows = items));
If you do not want to set this.rows when normally subscribing than you can also do this in the tap operator. But that would assume you only use it for checking difference between existing and new items.
This Meteor client public method needs to re run when the Meteor.user().profile.propA changes which is does fine, but it also runs when profile.propB changes or added. How can I stop it from re running when any other child property of profile has changed or added but only for profile.propA? Thanks
myListener: () => {
Tracker.autorun(() => {
if (Meteor.userId()) {
const indexes = Meteor.user().profile.propA;
if (!indexes || indexes.length <= 0) return;
dict.set('myStuff', indexes);
console.log('auto has run');
}
});
},
on the mongodb terminal:
db.users.update({'_id':'123abc'}, {$set: {'profile.propB':'B'}})
triggers the autorun. even though the reactive data source is Meteor.user().profile.propA;
Mongo.Collection.findOne allows you to specify which fields are retrieved from the local database using the fields option. Only changes to the fields specified there will trigger the autorun again.
Since Meteor.user() is just a shorthand for Meteor.users.findOne(Meteor.userId()), you can do the following to get updates for propA only:
const indexes = Meteor.users.findOne(Meteor.userId(), {
fields: {
'profile.propA': 1
}
});
Note that indexes will only contain profile.propA and the document's _id. If you need more data from the user document but still want to receive reactive updates separately, you have to fetch that data in a second autorun.
I'm using React with Meteor and am having trouble keeping my data updated. Here is my getMeteorData() code in a Conversation component
getMeteorData() {
var vertices_handle = Meteor.subscribe('VertexIDs', this.props.conversation_id);
return {
vertices: Vertices.find({conversation: this.props.conversation_id}).fetch(),
ready: vertices_handle.ready()
};
}
The subscription only returns the IDs of the posts (vertices) and I use this data to render more components:
renderPostList() {
return this.data.vertices.map((post) => {
return <PostThread
key = {post._id}
root_id = {post._id}
conversation_id = {this.props.conversation_id} />;
});
}
Within the PostThread component I subscribe to each post individually by its ID to get the rest of the data as needed. However, when I remove something from the Vertices collection, the Conversation component doesn't seem to be updating. I can see in MeteorToys that the Vertices collection on the client has removed a post, but this change sometimes isn't reflected in the UI. Sometimes when a post is removed the UI updates correctly but other times it doesn't and I have not been able to find a pattern to this.