47685 stream to blob #62298
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47685 stream to blob #62298
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@dotnet-policy-service agree |
martincostello
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@MaxxBahr could the same be achieved from user code ? The issue speaks about not loading the whole (video) stream into memory at the same time. This PR does load it all. |
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@pavelsavara : The design details for the blob() method are outlined in the related design proposal #61826. |
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Commenter does not have sufficient privileges for PR 62298 in repo dotnet/aspnetcore |
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/azp run |
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Commenter does not have sufficient privileges for PR 62298 in repo dotnet/aspnetcore |
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For starters, there need to be E2E tests for this. |
javiercn
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Sep 5, 2025
| */ | ||
| export function createJSObjectReference(jsObject: any): any { | ||
| if (jsObject && typeof jsObject === "object") { | ||
| if (jsObject && (typeof jsObject === "object" || jsObject instanceof Function)) { |
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It's unclear why this change is needed
javiercn
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| async readableStreamToBlob(mimeType: string = "application/octet-stream"): Promise<string> { | ||
| const reader = (await this.stream()).getReader(); | ||
| const chunks: BlobPart[] = []; | ||
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| while (true) { | ||
| const { done, value } = await reader.read(); | ||
| if (done) break; | ||
| chunks.push(value); | ||
| } | ||
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| const blob = new Blob(chunks, {type: mimeType}); | ||
| const url = URL.createObjectURL(blob); | ||
| return url; | ||
| } |
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This is not building a blob, but an object URL
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Add blob() method to JS side of Blazor DotNetStreamReference
Added method readableStreamToBlob() which returns a Blob from the given stream.
Description
The readableStreamToBlob method is an asynchronous function defined on the internal DotNetStream class. Its purpose is to convert a JavaScript ReadableStream (typically received from .NET interop) into a Blob URL that can be used in browser APIs (such as for downloads or displaying media).
Step-by-step Description
Obtain a Stream Reader:
The function first awaits the result of this.stream(), which returns a ReadableStream. It then calls .getReader() on this stream to obtain a reader for consuming the stream's data chunks.
Read All Chunks:
It initializes an empty array called chunks. Using a while (true) loop, it repeatedly calls reader.read(), which returns a promise resolving to an object with { done, value }.
If done is true, the stream has ended and the loop breaks.
Otherwise, it pushes the value (a chunk of data, typically a [Uint8Array]) into the [chunks] array.
Create a Blob:
After reading all chunks, it creates a new [Blob] from the collected [chunks] array. The mimeType parameter (defaulting to "application/octet-stream") is used as the Blob's type.
Create a Blob URL:
It then calls URL.createObjectURL(blob) to generate a temporary URL representing the Blob's data in memory.
Return the URL:
The function returns this Blob URL as a string. This URL can be used in browser contexts to reference the streamed data (for example, as a download link or image source).
Fixes #47685