Nuxt•4w ago

useFetch, how to type correctly.

I have this useFetch:

const updateRef = ref(0)
const { data, status } = useFetch(`/api/v2/locations/${parsedId}`, {
    watch: [updateRef],
})

const updateRef = ref(0)
const { data, status } = useFetch(`/api/v2/locations/${parsedId}`, {
    watch: [updateRef],
})

The route always returns 'status'. The optional return types are 'statusMessage', 'city', 'stones' and 'location'. The only type my IDE returns is 'status', as it's always present. How can I properly access optional fields without overriding the type in useFetch.

18 Replies

kapa.ai•4w ago

Hi @Kyllian. I'm kapa.ai, your friendly support bot. I will try to answer your question by searching through the knowledge base. :wave: ---------------------- To properly type your useFetch call to include optional fields, you need to provide a generic type parameter to useFetch. This allows TypeScript to know about all possible return fields, not just the ones that are always present. Here's how you can properly type your useFetch call:

interface LocationResponse {
  status: string;
  statusMessage?: string;
  city?: string;
  stones?: any; // Replace 'any' with the actual type of stones
  location?: any; // Replace 'any' with the actual type of location
}

const updateRef = ref(0)
const { data, status } = useFetch<LocationResponse>(`/api/v2/locations/${parsedId}`, {
  watch: [updateRef],
})

interface LocationResponse {
  status: string;
  statusMessage?: string;
  city?: string;
  stones?: any; // Replace 'any' with the actual type of stones
  location?: any; // Replace 'any' with the actual type of location
}

const updateRef = ref(0)
const { data, status } = useFetch<LocationResponse>(`/api/v2/locations/${parsedId}`, {
  watch: [updateRef],
})

By providing the LocationResponse interface as a generic type parameter to useFetch, TypeScript will know that data.value can have all these optional properties, even if they're not always returned from the API. This approach is consistent with the Nuxt documentation on typing useFetch calls. The type signature for useFetch allows you to specify the data type as a generic parameter:

function useFetch<DataT, ErrorT>(
  url: string | Request | Ref<string | Request> | (() => string | Request),
  options?: UseFetchOptions<DataT>
): Promise<AsyncData<DataT, ErrorT>>

function useFetch<DataT, ErrorT>(
  url: string | Request | Ref<string | Request> | (() => string | Request),
  options?: UseFetchOptions<DataT>
): Promise<AsyncData<DataT, ErrorT>>

As shown in the Nuxt documentation for useFetch, this ensures that your IDE and TypeScript will recognize all the possible fields in the response. Remember that data is a ref, so you'll need to access the properties using data.value.propertyName in your code. ---------------------- Note: you can ask me a follow up question by @ mentioning me again :speech_balloon: ----------------------

kapa.ai•4w ago

<@166602211780984832> Kapa.ai is still learning and improving, please let me know how I did by reacting below.

KyllianOP•4w ago

god this is absolute bollocks @kapa.ai Does Nuxt provide a way to simplify this? {{ typeof stone.person === 'object' ? stone.person.name ?? "" : stone.person }}

kapa.ai•4w ago

Let me check the knowledge base for you again. One moment! :books: ---------------------- Based on the knowledge sources provided, there isn't a specific Nuxt-provided utility function that directly simplifies this exact conditional expression pattern. However, Nuxt does provide some related functionality that might be helpful in certain scenarios: 1. When working with data from API responses, you could use the payload system to ensure proper serialization/deserialization of complex objects:

// You can define custom serializers/deserializers for complex types
definePayloadReducer('Person', (value) => {
  // Custom serialization logic
})
definePayloadReviver('Person', (value) => {
  // Custom deserialization logic
})

// You can define custom serializers/deserializers for complex types
definePayloadReducer('Person', (value) => {
  // Custom serialization logic
})
definePayloadReviver('Person', (value) => {
  // Custom deserialization logic
})

2. For UI components, Nuxt UI (if you're using it) provides components like UInputMenu and USelectMenu that have built-in handling for displaying object properties through the option-attribute prop:

<UInputMenu 
  v-model="selected" 
  :options="people" 
  option-attribute="name"
/>

<UInputMenu 
  v-model="selected" 
  :options="people" 
  option-attribute="name"
/>

Your specific conditional expression is a standard JavaScript pattern for safely accessing nested properties with fallbacks. While Nuxt doesn't have a built-in utility specifically for this pattern, you could create your own utility function if you use this pattern frequently:

// utils/format.js
export function getNestedProperty(obj, property, fallback = "") {
  return typeof obj[property] === 'object' ? obj[property]?.name ?? fallback : obj[property] ?? fallback
}

// utils/format.js
export function getNestedProperty(obj, property, fallback = "") {
  return typeof obj[property] === 'object' ? obj[property]?.name ?? fallback : obj[property] ?? fallback
}

Then use it in your template:

{{ getNestedProperty(stone, 'person', "") }}

{{ getNestedProperty(stone, 'person', "") }}

If you're looking for more advanced solutions for handling optional chaining and nullish coalescing in templates, you might want to consider using computed properties to simplify your template expressions. I hope this helps! Let me know if you need more specific guidance related to your Nuxt application. ---------------------- Note: you can ask me a follow up question by @ mentioning me again :speech_balloon: ----------------------

kapa.ai•4w ago

<@166602211780984832> Kapa.ai is still learning and improving, please let me know how I did by reacting below.

KyllianOP•4w ago

@kapa.ai how can I use a payload reducer in this: const { data, status } = useFetch<{ city: any, location: ILocation, stones: IStone[] }>(/api/v2/locations/${parsedId}, { watch: [updateRef], })

kapa.ai•4w ago

Let me check the knowledge base for you again. One moment! :books: ---------------------- To use a payload reducer with useFetch, you need to use the transform option rather than a payload reducer directly. Payload reducers are specifically for the Nuxt payload system (used with useNuxtApp().payload), while the transform option is what you need for transforming data from API responses with useFetch. Here's how you can implement it:

const { data, status } = useFetch<{ city: any, location: ILocation, stones: IStone[] }>(`/api/v2/locations/${parsedId}`, {
    watch: [updateRef],
    transform: (response) => {
        // Transform your response data here
        // For example, converting date strings to Date objects
        return {
            ...response,
            // Transform specific fields as needed
            stones: response.stones?.map(stone => ({
                ...stone,
                createdAt: stone.createdAt ? new Date(stone.createdAt) : undefined
            }))
        }
    }
})

const { data, status } = useFetch<{ city: any, location: ILocation, stones: IStone[] }>(`/api/v2/locations/${parsedId}`, {
    watch: [updateRef],
    transform: (response) => {
        // Transform your response data here
        // For example, converting date strings to Date objects
        return {
            ...response,
            // Transform specific fields as needed
            stones: response.stones?.map(stone => ({
                ...stone,
                createdAt: stone.createdAt ? new Date(stone.createdAt) : undefined
            }))
        }
    }
})

The transform function allows you to modify the response data before it's stored in the Nuxt payload, which helps minimize payload size and ensures proper typing Docs > Getting-started > Data Fetching. If you need to handle complex types like classes that aren't properly serialized by default, you can create a custom payload plugin to define reducers and revivers. This would be separate from your useFetch call:

// plugins/custom-payload.ts
export default definePayloadPlugin((nuxtApp) => {
  definePayloadReducer('YourCustomType', (value) => {
    // Return a serializable version of your custom type
    return value instanceof YourClass && value.toJSON()
  })
  
  definePayloadReviver('YourCustomType', (value) => {
    // Reconstruct your custom type from the serialized data
    return new YourClass(value)
  })
})

// plugins/custom-payload.ts
export default definePayloadPlugin((nuxtApp) => {
  definePayloadReducer('YourCustomType', (value) => {
    // Return a serializable version of your custom type
    return value instanceof YourClass && value.toJSON()
  })
  
  definePayloadReviver('YourCustomType', (value) => {
    // Reconstruct your custom type from the serialized data
    return new YourClass(value)
  })
})

This plugin will handle the serialization/deserialization of your custom types throughout your Nuxt application, including data fetched with useFetch Docs > Api > Composables > useNuxtApp. For more advanced serialization needs, you can also use an alternative serializer as shown in the Nuxt documentation Docs > Getting-started > Data Fetching. ---------------------- Note: you can ask me a follow up question by @ mentioning me again :speech_balloon: ----------------------

kapa.ai•4w ago

<@166602211780984832> Kapa.ai is still learning and improving, please let me know how I did by reacting below.

KyllianOP•4w ago

@kapa.ai how would I parse types in useFetch using transform:

const updateRef = ref(0)
const { data, status } = useFetch<{ city: any, location: ILocation, stones: IStone[] }>(`/api/v2/locations/${parsedId}`, {
    watch: [updateRef],
    transform(data) {
        data.location.name = data.location.name as ITranslatedText
        return data
    }
})

const updateRef = ref(0)
const { data, status } = useFetch<{ city: any, location: ILocation, stones: IStone[] }>(`/api/v2/locations/${parsedId}`, {
    watch: [updateRef],
    transform(data) {
        data.location.name = data.location.name as ITranslatedText
        return data
    }
})

kapa.ai•4w ago

Let me check the knowledge base for you again. One moment! :books: ---------------------- Your approach to using the transform function with useFetch is on the right track, but there are a few improvements we can make to ensure proper type handling. Here's how you can correctly use the transform function to parse types in useFetch:

const updateRef = ref(0)
const { data, status } = useFetch<{ city: any, location: ILocation, stones: IStone[] }>(`/api/v2/locations/${parsedId}`, {
    watch: [updateRef],
    transform: (response) => {
        // Create a new object to avoid mutating the original response
        return {
            ...response,
            location: {
                ...response.location,
                name: response.location.name as ITranslatedText
            }
        }
    }
})

const updateRef = ref(0)
const { data, status } = useFetch<{ city: any, location: ILocation, stones: IStone[] }>(`/api/v2/locations/${parsedId}`, {
    watch: [updateRef],
    transform: (response) => {
        // Create a new object to avoid mutating the original response
        return {
            ...response,
            location: {
                ...response.location,
                name: response.location.name as ITranslatedText
            }
        }
    }
})

The key improvements in this approach: 1. It's generally better to create a new object rather than mutating the original response data 2. The transform function allows you to modify the data before it's stored in the Nuxt payload This pattern is documented in the Nuxt documentation for data fetching, where the transform function is recommended for cases where you need more control over the response data or need to map over several objects Docs > Getting-started > Data Fetching. If you're dealing with complex nested objects or arrays, you can perform more extensive transformations:

transform: (response) => {
    return {
        ...response,
        location: {
            ...response.location,
            name: response.location.name as ITranslatedText
        },
        stones: response.stones?.map(stone => ({
            ...stone,
            // Transform stone properties as needed
            createdAt: stone.createdAt ? new Date(stone.createdAt) : undefined
        }))
    }
}

transform: (response) => {
    return {
        ...response,
        location: {
            ...response.location,
            name: response.location.name as ITranslatedText
        },
        stones: response.stones?.map(stone => ({
            ...stone,
            // Transform stone properties as needed
            createdAt: stone.createdAt ? new Date(stone.createdAt) : undefined
        }))
    }
}

Remember that the transform function doesn't prevent unwanted data from being fetched initially, but it will prevent unwanted data from being added to the payload transferred from server to client, which helps minimize payload size. ---------------------- Note: you can ask me a follow up question by @ mentioning me again :speech_balloon: ----------------------

kapa.ai•4w ago

<@166602211780984832> Kapa.ai is still learning and improving, please let me know how I did by reacting below.

KyllianOP•4w ago

@kapa.ai this messes with the typing

message.txt

kapa.ai•4w ago

Let me check the knowledge base for you again. One moment! :books: ---------------------- You're right to be concerned about how the transform function might affect typing in useFetch. The approach I suggested could indeed cause typing issues because TypeScript might not properly track the type transformations happening inside the transform function. Here's a better approach that preserves proper typing:

const updateRef = ref(0)
const { data, status } = useFetch<{ city: any, location: ILocation, stones: IStone[] }>(`/api/v2/locations/${parsedId}`, {
    watch: [updateRef],
    transform: (response) => {
        const result = {
            ...response,
            location: {
                ...response.location,
                name: response.location.name // Don't use type assertion here
            }
        }
        // Use satisfies to ensure type conformity without altering the type
        return result satisfies { city: any, location: ILocation, stones: IStone[] }
    }
})

const updateRef = ref(0)
const { data, status } = useFetch<{ city: any, location: ILocation, stones: IStone[] }>(`/api/v2/locations/${parsedId}`, {
    watch: [updateRef],
    transform: (response) => {
        const result = {
            ...response,
            location: {
                ...response.location,
                name: response.location.name // Don't use type assertion here
            }
        }
        // Use satisfies to ensure type conformity without altering the type
        return result satisfies { city: any, location: ILocation, stones: IStone[] }
    }
})

The satisfies operator (available in TypeScript 4.9+) is particularly useful here as it ensures type conformity without altering the object's type, which is better than using type assertions with as Github PR #28520. Alternatively, if you're working with a version of TypeScript that doesn't support satisfies, you could define your transformations in a type-safe way:

const updateRef = ref(0)
const { data, status } = useFetch<{ city: any, location: ILocation, stones: IStone[] }>(`/api/v2/locations/${parsedId}`, {
    watch: [updateRef],
    transform: (response) => {
        // Create a properly typed copy of the location object
        const location: ILocation = {
            ...response.location,
            // Handle the name property correctly according to its interface
            name: response.location.name
        }
        
        return {
            ...response,
            location
        }
    }
})

const updateRef = ref(0)
const { data, status } = useFetch<{ city: any, location: ILocation, stones: IStone[] }>(`/api/v2/locations/${parsedId}`, {
    watch: [updateRef],
    transform: (response) => {
        // Create a properly typed copy of the location object
        const location: ILocation = {
            ...response.location,
            // Handle the name property correctly according to its interface
            name: response.location.name
        }
        
        return {
            ...response,
            location
        }
    }
})

This approach ensures that TypeScript can properly track the types throughout the transformation process, maintaining type safety in your application. ---------------------- Note: you can ask me a follow up question by @ mentioning me again :speech_balloon: ----------------------

kapa.ai•4w ago

<@166602211780984832> Kapa.ai is still learning and improving, please let me know how I did by reacting below.

KyllianOP•4w ago

cool so there is no way to have this structure so much for DRY @kapa.ai is there absolutely NO way to clean this typeof data?.location.name === 'object' ? data?.location.name.en : data?.location.name || 'Loading'"

kapa.ai•4w ago

Let me check the knowledge base for you again. One moment! :books: ---------------------- Based on the knowledge sources provided, there isn't a specific built-in Nuxt utility that directly simplifies this exact conditional expression pattern. However, I can suggest a few approaches to make your code cleaner while maintaining proper typing. You could create a custom composable or utility function to handle this pattern:

// composables/useFormatting.js
export function useFormatting() {
  const getLocalizedText = (value, fallback = 'Loading') => {
    return typeof value === 'object' ? value?.en : value || fallback
  }
  
  return {
    getLocalizedText
  }
}

// composables/useFormatting.js
export function useFormatting() {
  const getLocalizedText = (value, fallback = 'Loading') => {
    return typeof value === 'object' ? value?.en : value || fallback
  }
  
  return {
    getLocalizedText
  }
}

Then in your component:

const { getLocalizedText } = useFormatting()

// Usage in template
{{ getLocalizedText(data?.location.name) }}

const { getLocalizedText } = useFormatting()

// Usage in template
{{ getLocalizedText(data?.location.name) }}

Alternatively, you could use a computed property to clean up your template:

const locationName = computed(() => {
  return typeof data.value?.location.name === 'object' 
    ? data.value?.location.name.en 
    : data.value?.location.name || 'Loading'
})

// In template
{{ locationName }}

const locationName = computed(() => {
  return typeof data.value?.location.name === 'object' 
    ? data.value?.location.name.en 
    : data.value?.location.name || 'Loading'
})

// In template
{{ locationName }}

The Nuxt documentation doesn't show a specific built-in utility for this exact pattern. The conditional expression you're using is a standard JavaScript pattern for safely accessing nested properties with fallbacks, and Nuxt doesn't have a specific shorthand for it. If you're using this pattern frequently throughout your application, creating your own utility function as shown above would be the most maintainable approach. I hope this helps! Let me know if you need more specific guidance related to your Nuxt application. ---------------------- Note: you can ask me a follow up question by @ mentioning me again :speech_balloon: ----------------------

kapa.ai•4w ago

<@166602211780984832> Kapa.ai is still learning and improving, please let me know how I did by reacting below.

KyllianOP•4w ago

whoow lets replace a lot of code with even more code

Gaming

Programming

useFetch, how to type correctly.

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