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fmbenhassine opened this issue Apr 28, 2025 · 6 comments · May be fixed by #4840
Open

Use contextual lambdas to configure batch artefacts #4818

fmbenhassine opened this issue Apr 28, 2025 · 6 comments · May be fixed by #4840
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in: infrastructure related-to: item-readers-writers type: feature
Milestone
6.0.0

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@fmbenhassine
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This request is about improving the builders of item readers and writers to use Lambdas for configuration options:

Current API:

var reader = new FlatFileItemReaderBuilder()
 .resource(...)
 .delimited()
 .delimiter(",")
 .quoteCharacter('"')
 ...
 .build();

Proposal:

var reader = new FlatFileItemReaderBuilder()
 .resource(...)
 .delimited ( config -> config.delimiter(',').quoteCharcter( '"' ))
 ...
 .build();

cc @joshlong
@fmbenhassine fmbenhassine added this to the 6.0.0 milestone Apr 28, 2025
@kwondh5217
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Hi @fmbenhassine,

This looks like a great improvement!
I would love to work on this issue. Could you please assign it to me if that's fine?

@fmbenhassine
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@kwondh5217 Sure! Thank you for your offer to help!

I believe Spring Security pioneered this configuration approach in the portfolio, so you can take a look there for inspiration.

@kwondh5217
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Hi @fmbenhassine, thank you for your guidance earlier!

I’d like to clarify the intended direction of the enhancement.

From what I understand, the idea is not just to support lambda-based configuration in FlatFileItemReaderBuilder, but to establish a general DSL-style configuration approach across all ItemReader and ItemWriter builders.

Would you recommend introducing a shared abstraction (e.g. a ConfigurerAwareBuilder base class similar to AbstractConfiguredSecurityBuilder in Spring Security) to support this pattern?

Also, in terms of behavior:

Should we throw an exception when both chaining and lambda styles are used?

Or should we allow overriding?

Or should we allow both and apply in order?

I want to align with the broader design direction before proceeding. Thank you again for your support.

@fmbenhassine
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I don't think we need new builders. My initial thinking was about adding new methods to existing builders that accept Consumer<Spec>, similar to the one in SF here: https://github.com/spring-projects/spring-framework/blob/main/spring-beans/src/main/java/org/springframework/beans/factory/BeanRegistry.java#L96

Here is also the original issue in Spring Security: spring-projects/spring-security#5557

So we can imagine new configuration specifications like DelimitedSpec, FixedLengthSpec, etc and use them in current builders.

@kwondh5217
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Thanks for the detailed guidance @fmbenhassine !
The direction is clear now. I’ll proceed with adding Consumer-based configuration methods to the existing builders using DelimitedSpec and FixedLengthSpec style objects as discussed.

I’ll share a draft PR soon for feedback. Appreciate your support!

@kwondh5217 kwondh5217 linked a pull request May 10, 2025 that will close this issue
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@kwondh5217
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Hi @fmbenhassine,
I’ve submitted a pull request that addresses this issue.
Could you take a look? 🙇‍♂️
Thank you !

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Support Lambda configuration in FlatFileItem builders kwondh5217/spring-batch
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@fmbenhassine @kwondh5217