I have an issue with my Vue webapp. Can you help advise on better solution than the one I implemented?
Sure, I'd be happy to help! Please provide more details on the issue you're facing and the solution you've implemented so far. That way, I can understand the problem better and offer a more informed advice.
The simplified version of my app has a search bar (component) present on all pages. When a user enters a query into the search bar, the component uses the Vue router to programmatically navigate to a search URL, e.g. if the user enter "Carl Sagan", the app would navigate to "/search?q=Carl+Sagan"
Okay, that sounds like a reasonable approach. What specific issue are you facing with this implementation?
Now, if the user is on the search page "/search?q=Carl+Sagan" and enters text into the search bar, "Isaac Asimov", it will navigate accordingly. If the user issues the browser back command, it will navigate correctly back to "/search?q=Carl+Sagan" and show the correct search results. The problem is that search bar text still shows "Isaac Asimov"
I see. This issue is happening because when the user presses the back button, the search page is being loaded from the browser cache and the search bar component is being re-rendered with its previous state, which is "Isaac Asimov". To fix this issue, you can update the search bar component to read the current search query from the URL parameters, rather than from its own state.Here's one possible solution:In your search bar component, add a query prop to accept the current search query as a parameter.In the mounted lifecycle hook of the search bar component, read the q parameter from the URL using this.$route.query.q, and set the query prop to this value.In the template of the search bar component, bind the value of the input field to the query prop using v-model.By doing this, the search bar component will always display the current search query from the URL, even if the page is loaded from the browser cache.Here's an example
<template>
<div>
<input type="text" v-model="query" @input="updateSearch" />
<button @click="search">Search</button>
</div>
</template>
<script>
export default {
props: {
query: {
type: String,
default: "",
},
},
mounted() {
this.query = this.$route.query.q || "";
},
methods: {
updateSearch() {
this.$router.replace({ query: { q: this.query } });
},
search() {
this.$router.push({ path: "/search", query: { q: this.query } });
},
},
};
</script>In this example, the query prop is used to store the current search query, which is initialized from the q parameter in the URL in the mounted hook. The updateSearch method is called whenever the input field is changed, and it updates the q parameter in the URL using this.$router.replace. The search method is called when the user clicks the search button, and it navigates to the search page using this.$router.push.
I used something similar to this, but Vue does not like a prop being used with v-model since it is now mutable. I had to assign the prop to another variable which is used instead for the v-model binding. Something like this:
<input v-model="searchText" />
...
data() { return {searchText = this.query} }
...Yes, you're correct. In Vue 2, using a prop with v-model can cause issues because props are not meant to be mutated by child components. Assigning the prop value to a data property is a good solution to avoid this problem.Here's the updated code that uses a data property instead of a prop for v-model
<template>
<div>
<input type="text" v-model="searchText" @input="updateSearch" />
<button @click="search">Search</button>
</div>
</template>
<script>
export default {
props: {
query: {
type: String,
default: "",
},
},
data() {
return {
searchText: this.query,
};
},
mounted() {
this.searchText = this.query;
},
methods: {
updateSearch() {
this.$router.replace({ query: { q: this.searchText } });
},
search() {
this.$router.push({ path: "/search", query: { q: this.searchText } });
},
},
};
</script>In this updated code, the searchText data property is initialized with the value of query from the prop in the mounted hook. The updateSearch and search methods use searchText instead of query to update the URL parameters.This approach avoids the issue with using a prop with v-model, and ensures that the search bar component always displays the correct search query, even when the page is loaded from the browser cache.
So the problem now becomes, whether in the mounted hook or in data initialization, the assignment of searchText happens only once and is not reactive. So what I had to do was add a watch hook on the prop.
watch() {
query: function() {this.searchText = this.query}
}this works fine, but it seems unnecessarily convoluted. So now I'm curious whether there is more svelte solution. What do you think?
You're correct that using a watch hook is a good way to ensure that the searchText data property stays in sync with the query prop. However, as you pointed out, it can be a bit verbose and add some unnecessary complexity to the code.One alternative solution you could consider is using a computed property to handle the synchronization between the searchText data property and the query prop. Here's an example:
<template>
<div>
<input type="text" v-model="searchText" @input="updateSearch" />
<button @click="search">Search</button>
</div>
</template>
<script>
export default {
props: {
query: {
type: String,
default: "",
},
},
data() {
return {
searchText: "",
};
},
computed: {
querySync: {
get() {
return this.query;
},
set(newValue) {
this.$router.replace({ query: { q: newValue } });
},
},
},
mounted() {
this.searchText = this.query;
},
methods: {
updateSearch() {
this.querySync = this.searchText;
},
search() {
this.$router.push({ path: "/search", query: { q: this.searchText } });
},
},
};
</script>In this updated code, we define a computed property querySync, which acts as a two-way binding between the query prop and the searchText data property. The get function simply returns the current value of the query prop, while the set function updates the URL parameters using this.$router.replace.In the mounted hook, we set the initial value of searchText to the value of query. Whenever the user types something into the input field, the updateSearch method is called and updates the querySync computed property, which in turn updates the URL parameters. The search method uses searchText to navigate to the search page, just like before.This approach ensures that the searchText data property stays in sync with the query prop, without the need for a watch hook or additional code.
Oh that's much better. The computed property is more declarative and explicit. Do you want to discuss the parent component (actually Root component) that renders the search bar?
Sure, let's discuss the Root component that renders the search bar. What do you want to know?
It has a similar reactive issue as the searchbar. Let's call the searchbar component "SearchBar". So using our example above the Root component template looks something like
<template>
<SearchBar :query="query" />
<router-view></router-view>
</template>I see. So you're passing the query data property from the Root component to the SearchBar component as a prop, and you want to make sure that any changes to the query in the URL parameters are reflected in the SearchBar component.To achieve this, you can use a similar approach to the one we used in the SearchBar component. Instead of using a watch hook, you can use a computed property to ensure that the query data property stays in sync with the URL parameters.Here's an example
<template>
<SearchBar :query="query" />
<router-view></router-view>
</template>
<script>
export default {
computed: {
query: {
get() {
return this.$route.query.q || "";
},
set(newValue) {
this.$router.replace({ query: { q: newValue } });
},
},
},
};
</script>In this updated code, we define a computed property query that acts as a two-way binding between the query data property and the URL parameters. The get function checks if the q parameter is present in the URL and returns its value, or an empty string if it's not present. The set function updates the URL parameters using this.$router.replace.By using a computed property, any changes to the query parameter in the URL will automatically update the query data property in the Root component, which in turn will be passed down to the SearchBar component as a prop. This ensures that the SearchBar component stays in sync with the URL parameters, without the need for a watch hook or additional code.
Wow you're one step ahead of me... yes that's exactly the issue (also had to add a watch hook on $route). By the way, when I'm typing in code fragments, is there a preferred format you would like me to use. I default to using markdown syntax, but it might be clearer if I used something else?
Markdown syntax is perfectly fine for code fragments. It's a widely used format that is easy to read and understand. Just make sure to use code blocks (i.e., wrap your code fragments in triple backticks) to ensure that the code is formatted properly.
thanks so much, this was really productive. Let's pair again soon
You're welcome! It was a pleasure helping you out. Don't hesitate to reach out again if you need further assistance. Have a great day!