Unlike queries, mutations are typically used to create/update/delete data or perform server side-effects. For this purpose, TanStack Query exports a useMutation hook.
Here's an example of a mutation that adds a new todo to the server:
<script setup>
import { useMutation } from '@tanstack/vue-query'
const { isLoading, isError, error, isSuccess, mutate } = useMutation({
mutationFn: (newTodo) => axios.post('/todos', newTodo),
})
function addTodo() {
mutate({ id: new Date(), title: 'Do Laundry' })
}
</script>
<template>
<span v-if="isLoading">Adding todo...</span>
<span v-else-if="isError">An error occurred: {{ error.message }}</span>
<span v-else-if="isSuccess">Todo added!</span>
<button @click="addTodo">Create Todo</button>
</template>
<script setup>
import { useMutation } from '@tanstack/vue-query'
const { isLoading, isError, error, isSuccess, mutate } = useMutation({
mutationFn: (newTodo) => axios.post('/todos', newTodo),
})
function addTodo() {
mutate({ id: new Date(), title: 'Do Laundry' })
}
</script>
<template>
<span v-if="isLoading">Adding todo...</span>
<span v-else-if="isError">An error occurred: {{ error.message }}</span>
<span v-else-if="isSuccess">Todo added!</span>
<button @click="addTodo">Create Todo</button>
</template>
A mutation can only be in one of the following states at any given moment:
Beyond those primary states, more information is available depending on the state of the mutation:
In the example above, you also saw that you can pass variables to your mutations function by calling the mutate function with a single variable or object.
Even with just variables, mutations aren't all that special, but when used with the onSuccess option, the Query Client's invalidateQueries method and the Query Client's setQueryData method, mutations become a very powerful tool.
It's sometimes the case that you need to clear the error or data of a mutation request. To do this, you can use the reset function to handle this:
<script>
import { useMutation } from '@tanstack/vue-query'
const { error, mutate, reset } = useMutation({
mutationFn: (newTodo) => axios.post('/todos', newTodo),
})
function addTodo() {
mutate({ id: new Date(), title: 'Do Laundry' })
}
</script>
<template>
<span v-else-if="error">
<span>An error occurred: {{ error.message }}</span>
<button @click="reset">Reset error</button>
</span>
<button @click="addTodo">Create Todo</button>
</template>
<script>
import { useMutation } from '@tanstack/vue-query'
const { error, mutate, reset } = useMutation({
mutationFn: (newTodo) => axios.post('/todos', newTodo),
})
function addTodo() {
mutate({ id: new Date(), title: 'Do Laundry' })
}
</script>
<template>
<span v-else-if="error">
<span>An error occurred: {{ error.message }}</span>
<button @click="reset">Reset error</button>
</span>
<button @click="addTodo">Create Todo</button>
</template>
useMutation comes with some helper options that allow quick and easy side-effects at any stage during the mutation lifecycle. These come in handy for both invalidating and refetching queries after mutations and even optimistic updates
useMutation({
mutationFn: addTodo,
onMutate: (variables) => {
// A mutation is about to happen!
// Optionally return a context containing data to use when for example rolling back
return { id: 1 }
},
onError: (error, variables, context) => {
// An error happened!
console.log(`rolling back optimistic update with id ${context.id}`)
},
onSuccess: (data, variables, context) => {
// Boom baby!
},
onSettled: (data, error, variables, context) => {
// Error or success... doesn't matter!
},
})
useMutation({
mutationFn: addTodo,
onMutate: (variables) => {
// A mutation is about to happen!
// Optionally return a context containing data to use when for example rolling back
return { id: 1 }
},
onError: (error, variables, context) => {
// An error happened!
console.log(`rolling back optimistic update with id ${context.id}`)
},
onSuccess: (data, variables, context) => {
// Boom baby!
},
onSettled: (data, error, variables, context) => {
// Error or success... doesn't matter!
},
})
When returning a promise in any of the callback functions it will first be awaited before the next callback is called:
useMutation({
mutationFn: addTodo,
onSuccess: async () => {
console.log("I'm first!")
},
onSettled: async () => {
console.log("I'm second!")
},
})
useMutation({
mutationFn: addTodo,
onSuccess: async () => {
console.log("I'm first!")
},
onSettled: async () => {
console.log("I'm second!")
},
})
You might find that you want to trigger additional callbacks beyond the ones defined on useMutation when calling mutate. This can be used to trigger component-specific side effects. To do that, you can provide any of the same callback options to the mutate function after your mutation variable. Supported options include: onSuccess, onError and onSettled. Please keep in mind that those additional callbacks won't run if your component unmounts before the mutation finishes.
useMutation({
mutationFn: addTodo,
onSuccess: (data, variables, context) => {
// I will fire first
},
onError: (error, variables, context) => {
// I will fire first
},
onSettled: (data, error, variables, context) => {
// I will fire first
},
})
mutate(todo, {
onSuccess: (data, variables, context) => {
// I will fire second!
},
onError: (error, variables, context) => {
// I will fire second!
},
onSettled: (data, error, variables, context) => {
// I will fire second!
},
})
useMutation({
mutationFn: addTodo,
onSuccess: (data, variables, context) => {
// I will fire first
},
onError: (error, variables, context) => {
// I will fire first
},
onSettled: (data, error, variables, context) => {
// I will fire first
},
})
mutate(todo, {
onSuccess: (data, variables, context) => {
// I will fire second!
},
onError: (error, variables, context) => {
// I will fire second!
},
onSettled: (data, error, variables, context) => {
// I will fire second!
},
})
There is a slight difference in handling onSuccess, onError and onSettled callbacks when it comes to consecutive mutations. When passed to the mutate function, they will be fired up only once and only if the component is still mounted. This is due to the fact that mutation observer is removed and resubscribed every time when the mutate function is called. On the contrary, useMutation handlers execute for each mutate call.
Be aware that most likely, mutationFn passed to useMutation is asynchronous. In that case, the order in which mutations are fulfilled may differ from the order of mutate function calls.
useMutation({
mutationFn: addTodo,
onSuccess: (data, error, variables, context) => {
// Will be called 3 times
},
})[('Todo 1', 'Todo 2', 'Todo 3')].forEach((todo) => {
mutate(todo, {
onSuccess: (data, error, variables, context) => {
// Will execute only once, for the last mutation (Todo 3),
// regardless which mutation resolves first
},
})
})
useMutation({
mutationFn: addTodo,
onSuccess: (data, error, variables, context) => {
// Will be called 3 times
},
})[('Todo 1', 'Todo 2', 'Todo 3')].forEach((todo) => {
mutate(todo, {
onSuccess: (data, error, variables, context) => {
// Will execute only once, for the last mutation (Todo 3),
// regardless which mutation resolves first
},
})
})
Use mutateAsync instead of mutate to get a promise which will resolve on success or throw on an error. This can for example be used to compose side effects.
const mutation = useMutation({ mutationFn: addTodo })
try {
const todo = await mutation.mutateAsync(todo)
console.log(todo)
} catch (error) {
console.error(error)
} finally {
console.log('done')
}
const mutation = useMutation({ mutationFn: addTodo })
try {
const todo = await mutation.mutateAsync(todo)
console.log(todo)
} catch (error) {
console.error(error)
} finally {
console.log('done')
}
By default TanStack Query will not retry a mutation on error, but it is possible with the retry option:
const mutation = useMutation({
mutationFn: addTodo,
retry: 3,
})
const mutation = useMutation({
mutationFn: addTodo,
retry: 3,
})
If mutations fail because the device is offline, they will be retried in the same order when the device reconnects.
Mutations can be persisted to storage if needed and resumed at a later point. This can be done with the hydration functions:
const queryClient = new QueryClient()
// Define the "addTodo" mutation
queryClient.setMutationDefaults(['addTodo'], {
mutationFn: addTodo,
onMutate: async (variables) => {
// Cancel current queries for the todos list
await queryClient.cancelQueries({ queryKey: ['todos'] })
// Create optimistic todo
const optimisticTodo = { id: uuid(), title: variables.title }
// Add optimistic todo to todos list
queryClient.setQueryData(['todos'], (old) => [...old, optimisticTodo])
// Return context with the optimistic todo
return { optimisticTodo }
},
onSuccess: (result, variables, context) => {
// Replace optimistic todo in the todos list with the result
queryClient.setQueryData(['todos'], (old) =>
old.map((todo) =>
todo.id === context.optimisticTodo.id ? result : todo,
),
)
},
onError: (error, variables, context) => {
// Remove optimistic todo from the todos list
queryClient.setQueryData(['todos'], (old) =>
old.filter((todo) => todo.id !== context.optimisticTodo.id),
)
},
retry: 3,
})
// Start mutation in some component:
const mutation = useMutation({ mutationKey: ['addTodo'] })
mutation.mutate({ title: 'title' })
// If the mutation has been paused because the device is for example offline,
// Then the paused mutation can be dehydrated when the application quits:
const state = dehydrate(queryClient)
// The mutation can then be hydrated again when the application is started:
hydrate(queryClient, state)
// Resume the paused mutations:
queryClient.resumePausedMutations()
const queryClient = new QueryClient()
// Define the "addTodo" mutation
queryClient.setMutationDefaults(['addTodo'], {
mutationFn: addTodo,
onMutate: async (variables) => {
// Cancel current queries for the todos list
await queryClient.cancelQueries({ queryKey: ['todos'] })
// Create optimistic todo
const optimisticTodo = { id: uuid(), title: variables.title }
// Add optimistic todo to todos list
queryClient.setQueryData(['todos'], (old) => [...old, optimisticTodo])
// Return context with the optimistic todo
return { optimisticTodo }
},
onSuccess: (result, variables, context) => {
// Replace optimistic todo in the todos list with the result
queryClient.setQueryData(['todos'], (old) =>
old.map((todo) =>
todo.id === context.optimisticTodo.id ? result : todo,
),
)
},
onError: (error, variables, context) => {
// Remove optimistic todo from the todos list
queryClient.setQueryData(['todos'], (old) =>
old.filter((todo) => todo.id !== context.optimisticTodo.id),
)
},
retry: 3,
})
// Start mutation in some component:
const mutation = useMutation({ mutationKey: ['addTodo'] })
mutation.mutate({ title: 'title' })
// If the mutation has been paused because the device is for example offline,
// Then the paused mutation can be dehydrated when the application quits:
const state = dehydrate(queryClient)
// The mutation can then be hydrated again when the application is started:
hydrate(queryClient, state)
// Resume the paused mutations:
queryClient.resumePausedMutations()
If you persist offline mutations with the persistQueryClient plugin, mutations cannot be resumed when the page is reloaded unless you provide a default mutation function.
This is a technical limitation. When persisting to an external storage, only the state of mutations is persisted, as functions cannot be serialized. After hydration, the component that triggers the mutation might not be mounted, so calling resumePausedMutations might yield an error: No mutationFn found.
const client = new QueryClient({
defaultOptions: {
queries: {
cacheTime: 1000 * 60 * 60 * 24, // 24 hours
},
},
})
// we need a default mutation function so that paused mutations can resume after a page reload
queryClient.setMutationDefaults({
mutationKey: ['todos'],
mutationFn: ({ id, data }) => {
return api.updateTodo(id, data)
},
})
const vueQueryOptions: VueQueryPluginOptions = {
queryClient: client,
clientPersister: (queryClient) => {
return persistQueryClient({
queryClient,
persister: createSyncStoragePersister({ storage: localStorage }),
})
},
clientPersisterOnSuccess: (queryClient) => {
queryClient.resumePausedMutations()
},
}
createApp(App).use(VueQueryPlugin, vueQueryOptions).mount('#app')
const client = new QueryClient({
defaultOptions: {
queries: {
cacheTime: 1000 * 60 * 60 * 24, // 24 hours
},
},
})
// we need a default mutation function so that paused mutations can resume after a page reload
queryClient.setMutationDefaults({
mutationKey: ['todos'],
mutationFn: ({ id, data }) => {
return api.updateTodo(id, data)
},
})
const vueQueryOptions: VueQueryPluginOptions = {
queryClient: client,
clientPersister: (queryClient) => {
return persistQueryClient({
queryClient,
persister: createSyncStoragePersister({ storage: localStorage }),
})
},
clientPersisterOnSuccess: (queryClient) => {
queryClient.resumePausedMutations()
},
}
createApp(App).use(VueQueryPlugin, vueQueryOptions).mount('#app')
We also have an extensive offline example that covers both queries and mutations.