Classic Google App Engine - storing an uploaded image to Cloud Storage - how to, on local dev environment?

[david...@gmail.com]

Hi, I really need some help here - I've spent ages experimenting and trying to find a good example on how to upload an image from browser to Cloud Storage that doesn't involve user ownership with oAuth, but now I've read this comment in a sample:

https://github.com/GoogleCloudPlatform/gcloud-golang/blob/master/examples/storage/appengine/app.go

// NOTE: the cloud.google.com/go/storage package is not compatible with

// dev_appserver.py, so this example will not work in a local development

// environment.

I'm wondering, is it even possible? How do I write my app if I can't run on my local machine?

[Dave Day]

Can you explain a little about what you mean by "user ownership with OAuth"? What use case are you aiming at?

The easiest way to get uploads from users in app engine is with blobstore.UploadURL and its partner blobstore.ParseUpload (https://godoc.org/google.golang.org/appengine/blobstore#UploadURL). Both of these URLs work perfectly well with the dev environment.

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[david...@gmail.com]

I'm wanting the user to fil out a form in the browser, most of the fields will end up in the datastore but the user can also upload an image from a file field within the multipart form. That image will be public, i.e. not owned by them. This image will then be used by the site on various pages.

As to the blobstore, the docs recommend using Cloud Storage instead; I have not found any statements that say Cloud Storage does not work with classic app engine.

Thanks, for helping out here.

[Dave Day]

It sounds like that will suit your needs then. Note that you can specify a bucket name in the upload options which make sure the upload ends up in cloud storage:

https://godoc.org/google.golang.org/appengine/blobstore#UploadURLOptions

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[david...@gmail.com]

Thanks Dave, I have your suggest approach working. (Who would have known to use the blobstore library to upload to cloud storage?)

I specified my default cloud storage bucket in the options to blobstore.UploadURL.

However, in the cloud storage console, it looks like my image has been uploaded to the blobstore until I click an icon and then I get this popup:

"This blob is stored in Google Cloud Storage. However, you should not manage it there. If you move, copy, or rename your blob in Google Cloud Storage, you will no longer be able to access it in Blobstore."

So now I'm a bit worried that this method is going to come back and bite me. Should I be concerned?

On Friday, August 12, 2016 at 1:03:21 PM UTC+10, Dave Day wrote:

It sounds like that will suit your needs then. Note that you can specify a bucket name in the upload options which make sure the upload ends up in cloud storage:

https://godoc.org/google.golang.org/appengine/blobstore#UploadURLOptions

On 12 August 2016 at 12:43, <david...@gmail.com> wrote:

I'm wanting the user to fil out a form in the browser, most of the fields will end up in the datastore but the user can also upload an image from a file field within the multipart form. That image will be public, i.e. not owned by them. This image will then be used by the site on various pages.

As to the blobstore, the docs recommend using Cloud Storage instead; I have not found any statements that say Cloud Storage does not work with classic app engine.

Thanks, for helping out here.

On Friday, August 12, 2016 at 11:21:38 AM UTC+10, Dave Day wrote:

Can you explain a little about what you mean by "user ownership with OAuth"? What use case are you aiming at?

The easiest way to get uploads from users in app engine is with blobstore.UploadURL and its partner blobstore.ParseUpload (https://godoc.org/google.golang.org/appengine/blobstore#UploadURL). Both of these URLs work perfectly well with the dev environment.

On 11 August 2016 at 16:58, <david...@gmail.com> wrote:

Hi, I really need some help here - I've spent ages experimenting and trying to find a good example on how to upload an image from browser to Cloud Storage that doesn't involve user ownership with oAuth, but now I've read this comment in a sample:

https://github.com/GoogleCloudPlatform/gcloud-golang/blob/master/examples/storage/appengine/app.go

// NOTE: the cloud.google.com/go/storage package is not compatible with

// dev_appserver.py, so this example will not work in a local development

// environment.

I'm wondering, is it even possible? How do I write my app if I can't run on my local machine?

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[Dave Day]

"This blob is stored in Google Cloud Storage. However, you should not manage it there. If you move, copy, or rename your blob in Google Cloud Storage, you will no longer be able to access it in Blobstore."

So now I'm a bit worried that this method is going to come back and bite me. Should I be concerned?

Only if you're planning to move, copy or rename your blob :)

Basically if you're planning to access the blobs/objects only through the google.golang.org/appengine/blobstore package then you'll be fine.

If you want to use a combination approach (by accessing GCS directly), then you will need to be more careful. For example, if you upload an object using "blobstore.UploadURL" and then move it in GCS, you may invalidate the associated appengine.BlobKey and make it unaccessible to blobstore.NewReader (for example).