Vue V Model Value

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Modified3 years, 1 month ago. Is there anyway to set a default value to an input to the value of another input field in case it has been left empty.Looks like I can't specify this in the data nor in the v-model attribute:.

Using Vue v-model in custom components

Any help is welcome.Thanks. 33 gold badges1616 silver badges2929 bronze badges. 2929 bronze badges. There is probably 37 different ways of doing it. The question is what is important, robustness, maintainability, ease of implementation, scalability etc. Here is a solution that prioritizes ease of implementation.

It relies on using @change and :value instead of the v-model magic. This will leave font2 and font3 as null if they are not changed. 1515 gold badges8585 silver badges133133 bronze badges. 133133 bronze badges. You will have to use a combination of v-model and computed properties' getters and setters to achieve what you want.

Declare an internal data store for the fonts, let's call the f1, f2, and f3. Give f1 your default value of 14:.

  • Now, when the component is mounted, you will want to interpolate the values accordingly.
  • This can be done in the vm.mounted() callback:. The last step is to setup your computed properties, so that whenever font1, font2, or font3 changes, they will update the internal font data store appropriately:.
  • See proof-of-concept below:. 1313 gold badges8181 silver badges104104 bronze badges.

104104 bronze badges. You could use a Boolean set to false for both input 1 and input 2 elements and update it to true when a value is entered. 11 gold badge1111 silver badges2929 bronze badges. 2929 bronze badges.

Using a nested object with v-model

Modified3 years, 3 months ago.

Working with nested arrays

So my searches on this topic are coming back with various GitHub issue tracking discussions from a while ago. Essentially, I have the following Bootstrap Select input:.

Using an object with v-model

Firstly, excuse the mix of v- and : binding syntax.

Secondly, the on-change binding is triggering the countryCountyConfiguration function, I have stripped it back to its simplest form for ease of debugging:.

Conclusion

Effectively, the best was I can describe this issue is that v-on:change="countryCountyConfiguration" is always one step behind v-model="selectedCountry" ..

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always displaying the previous v-model binding.

However, I really need the on change to feedback on country - such that if X country is chosen I will provide a dynamic choice of Counties and/or States. I was wondering, how would I get v-on:change="countryCountyConfiguration" and v-model="selectedCountry" to work in conjunction? 66 gold badges2727 silver badges5353 bronze badges. 5353 bronze badges. Ideally, that should not happen. It seems to be a problem with the component.

It would happen because change event is firing before the event which is responsible for v-model.

By default v-model uses :value and v-on:input as value and event pair.

In your case, you should resort to explicit one-way data binding and avoid the use of v-model as:.

Using v-model with null

Your countryCountyConfiguration will be:. 1313 gold badges4444 silver badges100100 bronze badges. 100100 bronze badges.

what about do it like this. using '$nextTick'.. Kyeseung KimKyeseung Kim. By using Vue's new Composition API, it feels like Vue's reactivity system has been freed of the constraints of the component. This article tells you that how to work with components and v-model more easily.

What is Vue v-model?

If you've worked with Vue, you know the v-model directive:. It's a great shortcut to save us from typing template markup like this:. The great thing is that we can also use it on components:. However, to implement this contract of a prop and an event, the component would have to look something like this:.

# The challenge: Reduce boilerplate

Basics of v-model

# Turn it into a composable

.lazy

This seems pretty verbose, however. We have to do this because we cannot directly write to the prop.We have to emit the correct event and leave it to the parent to decide how to deal with the update we communicate, because it’s the parent’s data, not that of our component.

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So we can’t use v-model on the input in this case. There are patterns of how to deal with this in the Options API that you may know from Vue 2, but today I want to look at how we can solve this challenge in a neat way with the tools offered by the Composition API.

What we want to achieve is an abstraction that lets us use the same v-model shortcut on the input, even though we don’t actually want to write to our local state and instead want to emit the correct event.

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This is what we want the template to look like when we’re done:. So let’s implement this with the composition API:. In setup, we create such a computed property, but a special one: our computed prop has a getter and setter, so we can actually read its derived value as well as assign it a new value.

Modifiers for v-model

This is how our computed prop behaves when used in Javascript:.

By returning this computed prop from the setup() function, we expose it to our template. And there, we can now use it with v-model to have a nice clean template:. Now the template is pretty clean.

But at the same time, we had to write a bunch of boilerplate in setup() to achieve this.

It seems we just moved the boilerplate from the template to the setup function.
So let’s extract this logic into its own function—a composition function—or for short: a “composable”.