Blob bindings can't set ContentType and other properties

[buchizo]

The blob output binding feature set always application/octet-stream to ContentType property. If possible, I would like to modified some blob properties.

And, Just now I don't found documents about some bindings. Example, Blob output binding can use %rand-guid%. And file name placeholder can use {name} from input binding.

I want to know details about bindings.

[christopheranderson]

This is definitely an issue. It would be helpful to know if you're trying to use C#/Node. Could just share a code sample with us?

We have a variety of ideas for how to make this smoother. We'd appreciate your input on how you'd like to set the Content Type, as well.

[buchizo]

Example: https://gist.github.com/buchizo/2f8ac640a21cd78920eccbfd7e0d267d

If I use CloudBlockBlob, I can set ContentType property. But it's not easily.

[christopheranderson]

Agreed that you shouldn't have to use CloudBlockBlob - we should aim to make this work cross language, which means using generic types.

[christopheranderson]

We should think through how we'd design this.

[christopheranderson]

I think this is related to binding data improvements we've had in mind for node.

[mathewc]

Another related issue here: https://github.com/Azure/azure-webjobs-sdk-script/issues/465. In general, we want to allow "object" bindings. I.e., allow a user to specify dataType: "object" in their binding metadata, which we translate to a JObject binding on the extension, with the extension handling the mapping from Blob/EventData => JObject, which can then be exposed to script.

[Adamsimsy]

Any progress on being able to configure the content/mimetype when the output type is "blob" in Azure functions?

[mathewc]

Not yet - we'll get to it :)

[Adamsimsy]

Cool looking forward to it :D

[ricklove]

Found this after making my feature request in #1664.

There, I specified that I would like to be able to set properties to static values like this:

{
    "name": "outOutputBlob",
    "type": "blob",
    "direction": "out",
    "path": "{container}/{blob}",
    "connection": "AZURE_STORAGE_CONNECTION_STRING",
    "properties": {
        "cacheControl": "public, max-age 86400",
        "contentType": "application/json",
        "contentEncoding": "gzip"
    }
}

Maybe to set the value at runtime:

context.bindings.outputBlob = {data: '...'};
context.bindingsMetadata.outputBlob.properties = {contentType:'application/json'}; 

[AlejandroGil]

Is there any progress on this?

[paulbatum]

No progress on this yet. Right now our main priority for JavaScript is getting the new out-of-proc model used in functions V2 to have feature and behavior parity with V1. Switching from Edge.js to a seperate node.exe process communicating over grpc is a pretty large change with a tail of bugs that will impact users trying to upgrade to V2 if not fixed.

[AlejandroGil]

Thank you Paul,

I finally resolved it using Azure storage SDK:

var azure = require('azure-storage');
var streamifier = require('streamifier');

var options = {contentSettings:{contentType:'application/xml'}}
content_stream = streamifier.createReadStream("content");
var blobService = azure.createBlobService("DefaultEndpointsProtocol=https;AccountName=.....");
content_stream.pipe(blobService.createWriteStreamToBlockBlob(container, outputFileName, options, function(error, result, response){...}

[lucasmike]

any update on this issues?

[paulbatum]

My comment above still reflects the current state.

[nemanjamil]

This is one of the solutions for upload image and set the adequate mime - content type https://github.com/nemanjamil/azure-functions/blob/master/azure_upload_image.js

[mikhailshilkov]

This basically means that the example from the docs (repeated twice) doesn't work. For some files (e.g. text/html), it copies the contents but breaks the content type. For others (e.g. png), it breaks the content too: I got the encoding messed up and a "copy" file is twice as long.

Tested with these bindings:

{"disabled":false,"bindings":[
  {"authLevel":"anonymous","type":"httpTrigger","direction":"in","name":"req","route":"{name}"},
  {"type":"http","direction":"out","name":"response"},
  {"name":"original","type":"blob","direction":"in","path":"files/{name}","connection":"StorageConnectionStringKey"},
  {"name":"copy","type":"blob","direction":"out","path":"files/copy-{name}","connection":"StorageConnectionStringKey"}
]}

[forki]

still not possible? that's a bummer

[shahedurrahman]

Is there any progress on this? Thanks

[eastonharvey]

Any updates on this? Would like to set properties on a Service Bus binding.

[matses]

any updates on this?

[alexanderomnix]

any update?

[SashiDareddy]

2021 and still waiting for this feature.

[invisibleaxm]

Any chance you we can get an update?

[NewFuture]

5 Years have passed!

[shanselman]

👀

[WestDiscGolf]

Just came across this issue. It also applied to the new isolated process model for C# as well. Any news?

[shanselman]

This is how Jeff Hollan solved it for me https://github.com/shanselman/azurefridayaggregator/pull/1/files

It's not clean, but it works. I would prefer that I be able to set the content type more readily in a single line.

On Sat, Jan 8, 2022 at 1:22 PM Adam Storr @.***> wrote:

Just came across this issue. It also applied to the new isolated process model for C# as well. Any news?

— Reply to this email directly, view it on GitHub https://github.com/Azure/azure-functions-host/issues/364#issuecomment-1008157025, or unsubscribe https://github.com/notifications/unsubscribe-auth/AAAAWTBDL24O5H3LCKAYLTLUVCTIHANCNFSM4CEKPBKA . You are receiving this because you commented.Message ID: @.***>

[WestDiscGolf]

@shanselman thanks for sharing the link. The Blob bindings in the new isolated model don't give those options unfortunately. I guess the only option will be to inject a BlockBlobClient manually through DI and save it that way instead of an BlobOutput binding.

[WestDiscGolf]

What I ended up doing was not using the binding at all.

1. Registering the BlobServiceClient in ConfigureServices

services.AddAzureClients(builder =>
        {
            builder.AddBlobServiceClient(hostContext.Configuration["AzureWebJobsStorage"]);
        });

2. Injecting into the azure function, through dependency injection, a BlobServiceClient.

3. In the timer function method getting a Blob Container Client.

var containerClient = _blobServiceClient.GetBlobContainerClient("my-blob-name");

4. Creating a BlockBlobClient from the Container client.

var blockClient = containerClient.GetBlockBlobClient("blob-name.json");

5. Writing the data to a stream and uploading it like @shanselman example.

Stream jsonStream = new MemoryStream();
await JsonSerializer.SerializeAsync(jsonStream, mydata, new JsonSerializerOptions() { WriteIndented = true });
jsonStream.Position = 0;
await blockClient.UploadAsync(jsonStream, new BlobHttpHeaders() { ContentType = "application/json" });

Hope this helps others.