React JS Local Storage update on view change - javascript

How can I update certain properties of a local storage item or object as new data is inputted throughout the user journey and not lose what was previously entered or if the user decides to update?
My journey of 5 containers consisting of asking the user to input the following:
Name: string
Avatar: integer
Favourite Genres: multiple strings
On the first view I have created the local storage object / item that sets the name within the handleSubmit function.
handleSubmit(event) {
event.preventDefault();
//Profile object
let profile = { 'name': this.state.name, 'avatar': null, 'genres': '' };
// Put the object into storage
localStorage.setItem('profile', JSON.stringify(profile));
// Retrieve the object from storage
var retrievedObject = localStorage.getItem('profile');
//Log object
console.log('retrievedObject: ', JSON.parse(retrievedObject));
//On form submission update view
this.props.history.push('/profile/hello');
}
On my second view I want to update only the avatar property and maintain what the user had inputted in the previous view.
I'm doing this within the handleSelect function like so:
handleSelect(i) {
let selectedAvatarId;
let avatars = this.state.avatars;
avatars = avatars.map((val, index) => {
val.isActive = index === i ? true : false;
return val;
});
this.setState({
selectedAvatarId: selectedAvatarId
})
//Profile object
let profile = { 'avatar': i };
//Update local storage with selected avatar
localStorage.setItem('profile', JSON.stringify(profile));
}

You will need to read the existing value from localStorage, parse it as JSON and then manipulate the data, and write it back. There are numerous libraries out there for easily working with localStorage, but something along the lines of this should work as a generic function:
function updateProfile = (updatedData) => {
const profile = JSON.parse(localStorage.getItem('profile'));
Object.keys(updatedData).forEach((key) => {
profile[key] = updatedData[key];
});
localStorage.setItem('profile', JSON.stringify(profile));
}
If you use object spread, it could look a lot cleaner too:
function updateProfile = (updatedData) => {
const profile = {
...JSON.parse(localStorage.getItem('profile')),
...updatedData
};
localStorage.setItem('profile', JSON.stringify(profile));
}
There should probably be some safety checks in the above code, but hopefully gives you an idea for a starting point.

The only option as far as I know is to get it as a Json, amend accordingly and then save it is again.

Related

How to pass data of an object to HTML file

I have few posts in my app, and I want that when user selects one of them, he to be redirected to a Post.html page which contains all details about that specific product. I have two methods, createPost() for creating a product dynamically where I pass postId in order to keep track of that product, and getPosts() to get the posts from database. I am saving all posts in an array in localStorage to have data about the selected product in Post.html. I added an addEventListener() but not sure how to use it. The problem is that I am stuck how to get the information of that post and pass it to Post.html.
function getPosts() {
firebase
.firestore()
.collection("products")
.get().then(snapshot => {
let products = [];
snapshot.docs.forEach((doc) => {
products.push(doc.data());
createPost(
doc.data().title,
doc.data().description,
doc.data().price,
doc.data().postId
);
});
localStorage.setItem(`${products}`, JSON.stringify(products));
})
.catch((err) => {
console.log(err);
});
}
function createPost(title, description, price, postId) {
let div = document.createElement("div");
div.setAttribute("class", "product-home-show");
......
div.appendChild(divSellerRoundImage);
div.appendChild(divSellerName);
div.appendChild(divProductDescription);
div.appendChild(divProductName);
div.appendChild(divProductPrice);
productsCollection.appendChild(div);
div.addEventListener("click", function () {
// console.log(localStorage.getItem());
// window.location.href = "post.html";
});
}
You can get data from localStorage on another page. Use localStorage.getItem(keyName); Also keep in mind the first argument to setItem is the key name. I'd recommend changing your code to: localStorage.setItem("products", JSON.stringify(products));. Then you'll be able to retrieve your product list with they key "products."
Also, if you're saving an object, you'll need to parse it since it will be saved as a string. You can use JSON.parse
For example:
var retrievedData = localStorage.getItem("products");
var productListObject = JSON.parse(retrievedData);
You can save the selected post ID in another value in local storage, or a cookie. Lastly, you may want to consider using sessionStorage if you don't need the data stored after the session is over. See this link for more information

object of data specific to current logged in user

The goal is the user can save up to 7 field vals in obj userA, logout, log back in and the saved vals are there, retrievable. Specific to each user.
I am trying to create an object i.e. userA and update it, as the
user saves each field value (i.e. BaseMap: basemapSaved), save
the updated state in local storage, then retrieve saved state using
local storage. So, when the user logs out, then logs back in, their
saved data is still there specific to their username.
Below is my most recent attempt (full js): Any pointers? Am I going about this all wrong?
UPDATED ATTEMPT BELOW WITH BOUNTY.
I am simply trying to save an object of data and a field within it (i.e. userA.BaseMap.basemapSaved;) with local storage, on click.
I later want to parse that saved object in local storage, get that field, and update my API object i.e. object.data.field (userA.BaseMap.basemapSaved;) with the value saved and gathered. I can do this pro grammatically pretty easy, but the idea is to save the state per user, so they can log out, then log back in and have their selection saved.
// Here I am trying to initialize the variables
var currentUser;
var basemapSaved;
var userA[key] = {};
// This function I am getting the logged in username, I want to set this as the object key in userA i.e. userA[key]
function checkUser() {
var node = document.querySelectorAll("span.username")[0];
currentUser = node.textContent;
var key = currentUser;
console.log("current user is:" + key);
}
// This is just a handler to wait to my basemap gallery loads before trying to save
var basemapMod = document.getElementsByClassName("basemap")[0];
basemapMod.addEventListener('click', ()=>{
setTimeout(
function() {
BaseMapSaver();
}, 2000);
});
function BaseMapSaver() {
savebtnBM.addEventListener('click', ()=>{
checkUser();
// This is where I get the data from my API to save, gathers fine
basemapSaved = app.widget.Manager.Gallery.activeBasemap.Item.id;
// Below I am trying to set it, at first without the object key but would like to use the key
var saveMap = localStorage.setItem('userA', JSON.stringify(userA));
console.log(userA);
});
}
// Home button
var defaultViewHbtn = document.getElementById("home");
defaultViewHbtn.addEventListener('click', ()=>{
checkUser();
// Here I try to parse the value from local storage object
const userAParseValue = JSON.parse(localStorage.getItem('userA'));
// Errors with Uncaught TypeError: Cannot read property 'BaseMap' of undefined
userBaseMap = userAParseValue.userA.BaseMap.basemapSaved;
console.log(userBaseMap);
app.widget.Manager.Gallery.activeBasemap.Item.id = {
portalItem: {
id: userA.BaseMap.basemapSaved // this is where I want to load saved value from local storage object
}
};
});
It Should work check addEventListener function:-
Hbtn.addEventListener('click', ()=>{
checkUser();
const userAParseValue = JSON.parse(localStorage.getItem('userA'));
userBaseMap = userAParseValue.userA.BaseMap.basemapSaved;
console.log(userBaseMap);
myApp.widgets.bigData.Gallery.map = {
Item: {
id: userA.BaseMap.basemapSaved
}
};
});
You can use localStorage and the approach you're trying to make work, but you'll end up with localStorage having a separate object for each user. If that's OK then you use localStorage after load to check if a user is logged in and then load the users' data. Then update the data to the localStorage when the values change. You may check inline comments for details:
HTML if there is a user logged in:
<h3>User <span class="username"><?php echo $user; ?></span> is logged in</h3>
<form method="post">
<input type="hidden" name="action" value="logout"/>
<button type="submit">Logout</button>
</form>
<hr/>
<div>
<h2>User counter: <span id="counter"></span></h2>
<div>
<button id="inc-counter">Increase</button>
<button id="dec-counter">Decrease</button>
</div>
</div>
Javascript to handle localStorage:
// Get user stored on page HTML
const user = document.querySelector("span.username");
// Something to update/alter using user data and/or user input
const counter = document.querySelector("#counter");
const incCounter = document.querySelector("#inc-counter");
const decCounter = document.querySelector("#dec-counter");
if(user) { // If there is a user logged in
// Get the username
const username = user.textContent;
// Get the localStorage the belongs to that user (using username for key)
let storageUser = JSON.parse(localStorage.getItem(username) || 'null');
// Use default user object if the user has no previous settings stored
let currentUser = storageUser || {
BaseMap: {
counter: 0
}
};
// Display the user data
function displayCounter() {
const BaseMap = 'BaseMap' in currentUser ? currentUser.BaseMap : {};
let userCounter = 'counter' in BaseMap ? BaseMap.counter : 0;
counter.textContent = userCounter;
}
// Alter the user data and save it to localStorage user settings object
function alterCounter(addToCounter) {
// Check if BaseMap object exists or default
const BaseMap = 'BaseMap' in currentUser ? currentUser.BaseMap : {};
// Check if data exists or default
let userCounter = 'counter' in BaseMap ? BaseMap.counter : 0;
// Alter user data according to user input
userCounter += addToCounter;
// Change user settings object
currentUser['BaseMap']['counter'] = userCounter;
// Save user settings object
localStorage.setItem(username, JSON.stringify(currentUser));
// Display altered user data
displayCounter();
}
// Initialize by display retrieved/default data
displayCounter();
// Add event listeners to user inputs
incCounter.addEventListener('click', () => alterCounter(1));
decCounter.addEventListener('click', () => alterCounter(-1));
}
You can check an online example that I've made at the link below:
https://zikro.gr/dbg/so/60010743/ (Users userA, userB both with password 1234 can be used for demonstration)
That will work and retrieve/save user data to the localStorage using username for each user. Keep in mind that this method will only save the user settings for a specific browser location. If you want to have user settings when the user logs in from anywhere, then you should go with the traditional workaround which is based on server session, but it's not so flexible when it comes to user settings because you'll have to update each data/setting using server requests each time the user makes a change which it's possible but it requires server + client implementation.
A combination of both server side settings storage + server session + client localStorage would be the best approach to this situation.
here is my answer
<html>
<body>
<span class="border username">121</span>
<div class="border basemap">Base Map</div>
<div class="border saveBtn">Save</div>
<div id="home" class="border">Home</div>
<style>
.border{
border: solid gray 1px;
border-radius: 2px;
text-align: center;
background: #eee;
margin: 5px;
width: 100px;
}
</style>
<script type="text/javascript">
// Here I am trying to initialize the variables
var key = 1;
var currentUser;
var basemapSaved;
var userA = {
BaseMap: {
id: 1234
}
};
var app = {
widget: {
Manager: {
Gallery: {
activeBasemap: {
Item: {
id: {
portalItem: {
id: 1234 // this is where I want to load saved value from local storage object
}
}
}
}
}
}
}
};
// This function I am getting the logged in username, I want to set this as the object key in userA i.e. userA[key]
function checkUser() {
var node = document.querySelectorAll("span.username")[0];
currentUser = node.textContent;
var key = currentUser;
console.log("current user is:" + key);
}
// This is just a handler to wait to my basemap gallery loads before trying to save
var basemapMod = document.getElementsByClassName("basemap")[0];
basemapMod.addEventListener('click', ()=>{
console.log("basemapMod click");
setTimeout(
function() {
BaseMapSaver();
}, 2000);
});
function BaseMapSaver() {
var savebtnBM = document.getElementsByClassName("saveBtn")[0];
savebtnBM.addEventListener('click', ()=>{
console.log("savebtnBM click");
checkUser();
// This is where I get the data from my API to save, gathers fine
basemapSaved = app.widget.Manager.Gallery.activeBasemap.Item.id.portalItem.id;
/** saving users, instead of userA */
const userAParseValue = JSON.parse(localStorage.getItem('users'));
userA.BaseMap.basemapSaved = basemapSaved;
const finalUsers = {...userAParseValue, userA}
// Below I am trying to set it, at first without the object key but would like to use the key
var saveMap = localStorage.setItem('users', JSON.stringify(finalUsers));
console.log(userA);
});
}
// Home button
var defaultViewHbtn = document.getElementById("home");
defaultViewHbtn.addEventListener('click', ()=>{
console.log("defaultViewHbtn click");
checkUser();
// Here I try to parse the value from local storage object
const userAParseValue = JSON.parse(localStorage.getItem('users'));
// Errors with Uncaught TypeError: Cannot read property 'BaseMap' of undefined
userBaseMap = userAParseValue.userA.BaseMap.basemapSaved;
console.log(userBaseMap);
app.widget.Manager.Gallery.activeBasemap.Item.id = {
portalItem: {
id: userA.BaseMap.basemapSaved // this is where I want to load saved value from local storage object
}
};
});
</script>
</body>
</html>
I changed a few structures which were not coherent. Saving and loading them was causing discrepancies. I also suggest storing all users in a single object and accessing the data from userMap because multiple users can use same browser.
Based on the two requirements that you have defined in your original question, this should do what you ask.
The goal is the user can save up to 7 field vals in obj userA, logout, log back in and the saved vals are there, retrievable. Specific to each user.
I am trying to create an object i.e. userA and update it, as the user saves each field value (i.e. BaseMap: basemapSaved), save the updated state in local storage, then retrieve saved state using local storage. So, when the user logs out, then logs back in, their saved data is still there specific to their username.
// retrieve user from localstorage. defaults to {}
// This looks to retrieve the user from local storage by username.
// Returns a `userObj` an object with two properties.
// `username` - the name of the user
// `user` - the stored object that was retrieved from local storage.
// defaults to {} if nothing in user storage
// Not a good strategy btw, a lot of us share the same names :)
function getUser(username) {
let user = localStorage.getItem(username) || {};
try {
user = JSON.parse(user);
} catch (e) {
user = {};
}
return { username, user }
}
// Store user object in localstorage
// Store a user in local storage, keyed by their username
function setUser(username, user) {
localStorage.setItem(username, JSON.stringify(user));
}
// set a key/ value on user object in localstorage
// Don't allow anymore than 7 properties to be stored on the user object
function setUserProperty(userObj, key, value) {
let { username, user } = userObj;
if (Object.keys(user).length > 7) {
throw new Error('user properties exceeds 7')
}
user[key] = value;
setUser(username, user);
}
// modified to return a user from local storage or {}
function checkUser() {
var node = document.querySelectorAll("span.username")[0];
const currentUser = node.textContent;
return getUser(currentUser);
}
// This is just a handler to wait to my basemap gallery loads before trying to save
var basemapMod = document.getElementsByClassName("basemap")[0];
basemapMod.addEventListener('click', () => {
setTimeout(
function() {
BaseMapSaver();
}, 2000);
});
// Fyi Capitals indicate constructors - not functions!
function BaseMapSaver() {
savebtnBM.addEventListener('click', () => {
const userObj = checkUser(); // get the user from localstorage
const basemapSaved = app.widget.Manager.Gallery.activeBasemap.Item.id;
setUserProperty(userObj, 'basemap', basemapSaved) // store the basemap on the user object in local storage with the key 'basemap'
console.log(JSON.stringify(userObj));
});
}
var defaultViewHbtn = document.getElementById("home");
defaultViewHbtn.addEventListener('click', () => {
// get user from localstorage
const { user } = checkUser();
const userBaseMap = user.basemap
// if we have a store basemap
if (userBaseMap) {
app.widget.Manager.Gallery.activeBasemap.Item.id = {
portalItem: {
id: userBaseMap // load it
}
};
}
});
There are many ways to handle this depending upon your use case. You have specifically mentioned LocalStorage hence everyone is suggesting the same but cookies will fit your bill as well as long as you handle the expiry time properly for them.
Local Storage
Make an Object of fields you will like to store for that user
let obj = {'keyname' : value, 'keyname' : value};
//store it - mapping it with user
localStorage.setItem('userID', JSON.stringify(obj));
//retrieve and use on login success
let ret_obj= localStorage.getItem('userID');
Cookies
You can set an arbitrary expiration time and then you again have choice of choosing just one variable or store it as a JSON itself.
document.cookie = "userName=Robert; expires=Fri, 31 Dec 9999 23:59:59 GMT";
*Cookies will hold limited amount of data, as in not huge data (Which I don't think is the use case here because I checked your jsfiddle example, you are basically trying to store some data)
If you want to store JSON data in cookies check this out Click Here
*Why am I suggesting cookies? Many enterprises already do something similar for example even post logging out when you visit a website
they will display your name and ask you to sign-in, it is just a
personalisation addition.

Async issue with State in React Native

I'm trying to build a simple app that lets the user type a name of a movie in a search bar, and get a list of all the movies related to that name (from an external public API).
I have a problem with the actual state updating.
If a user will type "Star", the list will show just movies with "Sta". So if the user would like to see the actual list of "Star" movies, he'd need to type "Star " (with an extra char to update the previous state).
In other words, the search query is one char behind the State.
How should it be written in React Native?
state = {
query: "",
data: []
};
searchUpdate = e => {
let query = this.state.query;
this.setState({ query: e }, () => {
if (query.length > 2) {
this.searchQuery(query.toLowerCase());
}
});
};
searchQuery = async query => {
try {
const get = await fetch(`${API.URL}/?s=${query}&${API.KEY}`);
const get2 = await get.json();
const data = get2.Search; // .Search is to get the actual array from the json
this.setState({ data });
} catch (err) {
console.log(err);
}
};
You don't have to rely on state for the query, just get the value from the event in the change handler
searchUpdate = e => {
if(e.target.value.length > 2) {
this.searchQuery(e.target.value)
}
};
You could keep state updated as well if you need to in order to maintain the value of the input correctly, but you don't need it for the search.
However, to answer what you're problem is, you are getting the value of state.query from the previous state. The first line of your searchUpdate function is getting the value of your query from the current state, which doesn't yet contain the updated value that triggered the searchUpdate function.
I don't prefer to send api call every change of letters. You should send API just when user stop typing and this can achieved by debounce function from lodash
debounce-lodash
this is the best practise and best for user and server instead of sending 10 requests in long phases
the next thing You get the value from previous state you should do API call after changing state as
const changeStateQuery = query => {
this.setState({query}, () => {
//call api call after already changing state
})
}

Firebase - Update specific fields simultaneously without replacing all of the data

I would like to be able to publish simultaneously in two directories of my Firebase database. I created a function for this, according to the example proposed in the "Update specific fields" section of the Firebase Javascript documentation:
function linkTwoUsers(user1, user2) {
// The two users are "connected".
var user1Data = {
userLink: user2
};
var user2Data = {
userLink: user1
};
var updates = {};
updates["/users/" + user1] = user1Data;
updates["/users/" + user2] = user2Data;
return database
.ref()
.update(updates)
.then(() => {
return res.status(200).end();
})
.catch(error => {
return res.status(500).send("Error: " + error.message);
});
}
The problem is that when I run the function, instead of uploading the directories, it replaces all the data present in it.
Here are the user directories before the function:
And then:
How do we make sure the data doesn't overwrite the others? Thank you for your help.
Try to narrow your path to just the property you are trying to update:
updates["/users/" + user1 + "/userLink/"] = user1;
updates["/users/" + user2 + "/userLink/"] = user2;
It seems as though you're creating an entirely new object when you set:
var userData = { someThing: stuff }
When you pass that in, it will override the original object. One way you might solve this (there might be a more efficient way) is to grab the objects from Firebase, add the new property and value to the object, then send the entire object back into Firebase.
In some javascript frameworks, you should be able to use the spread operator to set all of an object's props to another object like this:
var newObject = { ...originalObject }
newObject.userData = "something"
// then save newObject to firebase

how can i save object in mobille storage using react native

I am building an application in which I want to save user data. and user able to see that data later. I am using AsyncStorage.. i want to store multiple values in one key. I used AsyncStorage.setItem.. here is my code..
var obj ={
name : "sabih",
color : "blue"
}
AsyncStorage.setItem('myKey', JSON.stringify(obj))
.then(() => {
console.log('data saved')
})
but when i get data with AsyncStorage.getItem. it gives me like this
{"name":"sabih" , "color" : "blue"}
Code here
AsyncStorage.getItem("myKey").then((data) => {
var userData = JSON.parse(data)
console.log(userData, 'Get Values')
}).done();
How can i set name's and color's value in state. or how can i render these values in my react native application..
Thanks in advance.
and please attach a snap of solution if possible..
Create a function inside your file and call that function passing your asyncstrorage value as parameter as below :-
_renderDetail=(item)=>{
this.setState({user:item});
}
and inside your asyncStorage code edit as :-
AsyncStorage.getItem("myKey").then((data) => {
var userData = JSON.parse(data);
console.log(userData, 'Get Values');
this._renderDetail(userData);
}).done();
and then you can use this state variables inside your render function as :-
<Text>{this.state.user.name}</Text>
<Text>{this.state.user.color}</Text>

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