Support changing dataType for a binding in v4

v3 function.json content:

{
    "name": "myQueueItem",
    "type": "queueTrigger",
    "direction": "in",
    "queueName": "helloworldqueue",
    "connection": "storage_APPSETTING",
    "dataType": "binary"
}

v3 index.js content:

module.exports = async function (context, myQueueItem) {
    context.log('JavaScript queue trigger function processed work item', myQueueItem);
};

In v3 the type of myQueueItem changes based on the value of dataType. If you set dataType to binary, myQueueItem will be a Buffer. Otherwise, myQueueItem will either be a string or possibly a parsed object if the string was JSON.

In v4, we don't allow users to change myQueueItem to a Buffer type, which we should. This does not apply to http triggers, but probably applies to several other triggers/bindings other than storage queue.

Is there any news on this issue? Or a way to help fix it?

No updates, but this is still planned to be fixed before we GA. For a workaround, either use the v3 model or use generics:

import { app, InvocationContext, trigger } from "@azure/functions";

export async function storageQueueTrigger1(queueItem: unknown, context: InvocationContext): Promise<void> {
    context.log(`Is it a buffer? ${Buffer.isBuffer(queueItem)}`);
}

app.generic('storageQueueTrigger1', {
    trigger: trigger.generic({
        type: 'queueTrigger',
        queueName: 'testqueue',
        connection: 'storage_APPSETTING',
        dataType: 'binary'
    }),
    handler: storageQueueTrigger1
});

Eric Jizba (@ejizba)

Bumping into this, I have a storage extra input trying to load a PDF file, and I cannot get the blob content as a binary.

Eric Jizba (@ejizba) is there a workaround when using the v4 extraInputs for setting the dataType?

Daniel Castro (@castrodd)

This has been de-prioritized in favor of a feature that uses @azure/storage-blob sdk types, where basically we would give you a BlobClient as the trigger input or extra input and you can use the client to get the content however you want. Daniel Castro (@castrodd) is working on a prototype now, related to #99 and #203

In the meantime, the only workaround for extra inputs is to use the sdk and create the blob client yourself. There is no workaround for trigger inputs. Actually, I already mentioned a workaround above using generics, that should still work for both.

Thanks for the details! I ended up using @azure/storage-blob but I like to try using any opportunity to reduce/simplify code 🙂 I'll have a look at generics, seems like a nice workaround.

As its still not fixed yet you can use this workaround :

app.eventHub('LiveData', {
    connection: '...',
    eventHubName: 'messages/events',
    cardinality: 'many',
    consumerGroup: '%...%',
    handler: ...,
    dataType: 'binary',
} as any);

add the dataType and simply force cast as any and it works. it looks like it's just a typescript definition issue.

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Support changing dataType for a binding in v4 #72

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Support changing dataType for a binding in v4 #72

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vsantele commented on May 29, 2023

ejizba commented on May 31, 2023

sinedied commented on Mar 27, 2024

ejizba commented on Mar 28, 2024

sinedied commented on Mar 29, 2024

rohsyl commented on Jul 18, 2024

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