Conversion from *Input to *FluentBuilder

[robjtede]

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Describe the feature

An easy way to convert from *Inputs to *FluentBuilders or a way to use an *Input as a request as-is.

(I suspect the former is easier to accomplish and less of a semver hazard.)

Use Case

When an *Input is constructed elsewhere and passed into a function that starts constructing the *FluentBuilder using the S3 client, we are forced to deconstruct the already valid Input into the .set_*() methods provided which is error prone.

Proposed Solution

Using Rust RFC format:

impl ListObjectsV2FluentBuilder {
  pub fn from_input(input: ListObjectsV2Input) -> Self;
}

and etc. for other operations.

I'm mostly familiar with the S3 crate but imagine this applies to a wider scope.

Other Information

No response

Acknowledgements

• [ ] I may be able to implement this feature request
• [ ] This feature might incur a breaking change

A note for the community

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[rcoh]

Very reasonable! If you want to take a stab at it yourself, the relevant code is here.

For your use case, would you want a From impl, or would something like .set_input() or input_mut() work?

I'm also interested in your use case—you could construct the fluent builder and pass it around, but is the issue that you don't have access to the client at the time?

[robjtede]

Exactly. Our use case uses the Input and Output types in a trait interface that abstracts over in-memory, disk, and S3 "backends" but always trying to respect S3 parameter semantics.

Any of those alternative solutions would work for us, too.

[jdisanti]

I don't know if this helps your situation, but all input builder types have a send_with method: https://docs.rs/aws-sdk-s3/latest/aws_sdk_s3/operation/list_objects_v2/builders/struct.ListObjectsV2InputBuilder.html#method.send_with

[robjtede]

Almost. Would be enough if there was either:

• a way to convert an Input back into an InputBuilder
• a similar Input::send_with()

In general this just seems like a weird type dance that's done internally. Like, the thing that is sent is not the InputBuilder or the FluentBuilder; it's the Input! But it's so hard to use an input you have in any way.

[robjtede]

Luckily, I have control of the interface so I decided to change everything to *InputBuilders which does solve my specific issue since I now have access to send_with().