set Reader to Body

[mattn]

bind stdin to Body in the struct. Now it's possible to upload S3 object like below.

$ ./aws-sdk-client-go s3 PutObject '{"bucket": "my-upload-test", "key":"ないしょ.txt"} < ないしょ.txt'

[fujiwara]

@mattn Thank you! This is a great feature! But, I found a io.Reader field that is not named Body in another struct. For example lambda#InvokeAsyncInput.

I want to support these io.Reader fields by uniform flags (for example --bind-input Body=(filename or -). So, could you allow me to use the idea of this PR in my code? (of course I'll commit with co-author @mattn -san).

[mattn]

Yes, please

[mattn]

How can we set not only Body but also ContentType and ContentLength at the same time?

[fujiwara]

How can we set not only Body but also ContentType and ContentLength at the same time?

ContentType can be set into an Input struct as below.

$ aws-sdk-clent-go s3 PubObject '{"Bucket":"example","Key":"example","ContentType":"text/plain"}' ...

But ContentLength cannot be determined before it is read all from stdin.

For example, PutChunkInput has Data io.Reader and Length int64 fields, so we cannot generally decide the length field name.

As an idea, add --length-field=ContentLength to set the length after it is read all from stdin.

[fujiwara]

I searched Input structs that have io.Reader and *Length* fields from all.

2024/05/20 13:47:18 found io.Reader field in backupstorage.NotifyObjectCompleteInput MetadataBlob io.Reader
2024/05/20 13:47:18 found MetadataBlobLength field in backupstorage.NotifyObjectCompleteInput MetadataBlobLength MetadataBlobLength
2024/05/20 13:47:18 found io.Reader field in backupstorage.PutChunkInput Data io.Reader
2024/05/20 13:47:18 found Length field in backupstorage.PutChunkInput Length Length
2024/05/20 13:47:18 found io.Reader field in backupstorage.PutObjectInput InlineChunk io.Reader
2024/05/20 13:47:18 found InlineChunkLength field in backupstorage.PutObjectInput InlineChunkLength InlineChunkLength
2024/05/20 13:47:19 found io.Reader field in ebs.PutSnapshotBlockInput BlockData io.Reader
2024/05/20 13:47:19 found DataLength field in ebs.PutSnapshotBlockInput DataLength DataLength
2024/05/20 13:47:19 found io.Reader field in s3.PutObjectInput Body io.Reader
2024/05/20 13:47:19 found ContentLength field in s3.PutObjectInput ContentLength ContentLength
2024/05/20 13:47:19 found io.Reader field in s3.UploadPartInput Body io.Reader
2024/05/20 13:47:19 found ContentLength field in s3.UploadPartInput ContentLength ContentLength
2024/05/20 13:47:19 found io.Reader field in s3.WriteGetObjectResponseInput Body io.Reader
2024/05/20 13:47:19 found ContentLength field in s3.WriteGetObjectResponseInput ContentLength ContentLength

I think the length field can be set automatically by code generation.

[mattn]

If there will never be more than one Reader in a struct in the future, I see no problem with the --length-fied flag.

[fujiwara]

@mattn Sorry, I've missed committing past. Added co-author by this commit. bf89ea2

[mattn]

No prob 👍