Support passing `model` builders directly as parameters

[joshtriplett]

Describe the feature

Currently, calling a method that accepts a model struct requires first constructing the builder (ModelStruct::builder()), then calling methods on it, then calling .build() at the end. I'd love to leave off the .build() and have the method accepting the structure handle that, reducing boilerplate in the common case of constructing such a model struct and immediately passing it.

Use Case

Consider the following code:

        let reservation = self
            .ec2
            .run_instances()
            .launch_template(
                aws_sdk_ec2::model::LaunchTemplateSpecification::builder()
                    .launch_template_name(launch_template_name)
                    .build(),
            )
            .instance_type(instance_type.clone())
            /* ... */
            .send()
            .instrument(info_span!("RunInstances"))
            .await?;

If LaunchTemplateSpecification implemented From<Builder>, and launch_template accepted impl Into<LaunchTemplateSpecification>, that would allow leaving off the .build().

Proposed Solution

No response

Other Information

No response

Acknowledgements

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

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[Velfi]

I think this is an interesting proposal and I agree that less boilerplate is better. Thanks for submitting it.

[canadiannomad]

I'm running into this as well.. I find it very odd. Here is what I want to do:

• Get a ECS Task Definition (using describe_task_definition),
• Modify the returned TaskDefinition
• Send the TaskDefinition to register_task_definition

But the SDK won't let me do that. I have to manually rebuild that TaskDefinition with builder functions. I expect I'll have the same problem as I make changes to ALB Rules as well..

I've encountered this all over the SDK where it seems to deliberately prevent me from working with the Structs it provides me to repurpose for another purpose.

If I have a fully formed *Input(eg Lambda's InvokeInput, or SSM's GetParameterInput) struct, why am I not allowed to send it directly to the API?