Saving an `ArrayBuffer` with `defineCachedEventHandler` & NuxtHub cache

[vast swan]

I'm trying to return an ArrayBuffer (with an image) from my cached event handler.

This is working correctly with a regular handler, but with caching it returns {}, presumably because useStorage.set is used in cached functions instead of experimental setItemRaw.

Is there any way around this?

I thought of declaring a custom storage provider which only handles array buffers, but if I override the cache storage driver I'll override it for all of them?

I suppose I could wrap the NuxtHub cache driver, and detect ArrayBuffers with some more complex serialization but this seems very complicated?

[pearl girder]

Hi @vast swan. I'm kapa.ai, your friendly support bot. I will try to answer your question by searching through the knowledge base. :wave:

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Your question is about using defineCachedEventHandler with ArrayBuffers in Nuxt, which is a relevant topic for this AI assistant. Let's explore the available information to address your concern.

The issue you're facing with caching ArrayBuffers using defineCachedEventHandler is indeed related to the serialization process. By default, Nuxt uses JSON serialization for caching, which doesn't handle ArrayBuffers well.

Unfortunately, the provided knowledge sources don't contain specific information about handling ArrayBuffers with defineCachedEventHandler or using NuxtHub cache. However, we can explore some potential approaches based on the available information:

1. Custom Serialization:
   As mentioned in the Nuxt documentation on data fetching, Nuxt doesn't currently support an alternative serializer to JSON.stringify. However, you can return your payload as a normal string and utilize the toJSON method to maintain type safety. You could potentially adapt this approach to handle ArrayBuffers.

2. Using unstorage:
   Nuxt's caching system is built on top of unstorage. According to the unstorage documentation, there's an experimental setItemRaw method that might be suitable for ArrayBuffers. However, it's not clear if this is directly accessible through Nuxt's defineCachedEventHandler.

3. Custom Storage Driver:
   As you suggested, creating a custom storage driver could be a solution. The unstorage documentation on custom drivers provides information on how to create one. However, as you noted, overriding the entire cache storage driver might affect other parts of your application.

4. Wrapping Existing Driver:
   Your idea of wrapping the NuxtHub cache driver and detecting ArrayBuffers for special handling could be a viable solution, albeit complex. This approach would allow you to maintain the existing functionality while adding support for ArrayBuffers.

Given the limitations of the current caching system with ArrayBuffers, you might need to consider alternative approaches:

1. Convert the ArrayBuffer to a Base64 string before caching and convert it back when retrieving.
2. Store the ArrayBuffer separately (e.g., in the filesystem or a different storage system) and cache only a reference to it.
3. Use a different caching strategy for routes that return ArrayBuffers.

Unfortunately, there isn't a straightforward solution based on the provided knowledge sources. You might need to experiment with these approaches or seek more specific guidance from the Nuxt community or documentation.

If you decide to implement a custom solution, make sure to thoroughly test it to ensure it doesn't negatively impact the performance or functionality of your application.

Note: you can ask me a follow up question by @ mentioning me again :speech_balloon:

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