Proposal: Comprehensive Excel Data Validation System

[tianyufeng925]

Background

Hi FastExcel community! 👋

I've just submitted a focused PR that adds basic required field validation utilities to FastExcel. While working on this feature, I realized there's a broader opportunity to enhance FastExcel's data validation capabilities in a systematic way.

Current Contribution

The recently submitted PR includes:

• ExcelValidationUtils for required field validation
• @ExcelRequired annotation
• Comprehensive unit tests
• Full English documentation

This small but solid foundation got me thinking about the bigger picture...

Future Vision

I'd like to propose a comprehensive Excel data validation system that could include:

🎯 Dropdown Selection Validation

• @ExcelSelect annotation with predefined options
• Automatic dropdown creation in Excel templates
• Validation during data import

🔢 Numeric Range Validation

• @ExcelNumberValidation with min/max values
• Decimal places control
• Custom error messages with placeholders

📅 Date Range Validation

• @ExcelDateValidation with format specification
• Date range boundaries (min/max dates)
• Flexible date format support

🔧 Additional Features

• Auto-increment ID generation
• Default value handling
• Smart template adaptation

Benefits for FastExcel Community

1. Improved Data Quality - Prevent invalid data at the source
2. Better User Experience - Clear validation feedback in Excel
3. Enterprise Ready - Professional validation capabilities
4. Developer Friendly - Simple annotation-based approach
5. Backward Compatible - Zero impact on existing code

Implementation Approach

I propose implementing these features incrementally:

1. ✅ Phase 1: Required field validation (recently submitted)
2. 🎯 Phase 2: Dropdown selection validation
3. 📊 Phase 3: Numeric and date validation
4. 🚀 Phase 4: Advanced features (auto-increment, defaults)

Each phase would be a separate, focused PR that builds on the previous foundation.

Questions for the Community

1. Priority: Which validation features would be most valuable to you?
2. API Design: Do you prefer annotation-based or programmatic configuration?
3. Compatibility: Any concerns about maintaining backward compatibility?
4. Use Cases: What specific validation scenarios do you encounter?

Example Usage Vision

@Data
public class ProjectData {
    @AutoIncrementId(start = 1)
    @ExcelProperty("ID")
    private Integer id;
    
    @ExcelProperty("Project Type")
    @ExcelSelect({"Infrastructure", "Building", "Municipal", "Water"})
    private String projectType;
    
    @ExcelProperty("Budget")
    @ExcelNumberValidation(min = 0.0, max = 999999.99, decimalPlaces = 2)
    @ExcelRequired(message = "Budget is required")
    private BigDecimal budget;
    
    @ExcelProperty("Start Date")
    @ExcelDateValidation(format = "yyyy-MM-dd", minDate = "2020-01-01", maxDate = "2030-12-31")
    private Date startDate;
    
    @ExcelProperty("Department")
    @ExcelDefaultValue("Engineering")
    private String department;
}

// Usage
EasyExcel.write(fileName, ProjectData.class)
    .registerWriteHandler(new ExcelSelectHandler(ProjectData.class))
    .registerWriteHandler(new ExcelNumberValidationHandler(ProjectData.class))
    .registerWriteHandler(new ExcelDateValidationHandler(ProjectData.class))
    .registerWriteHandler(new ExcelDefaultValueHandler(ProjectData.class))
    .registerWriteHandler(new AutoIncrementIdHandler())
    .sheet("Project Data")
    .doWrite(dataList);

[wangmiscoding]

It seems there are some similarities with my PR. I think their suggestion to integrate with javax.validation.Validator is a great idea.

[AlchemyDing]

It seems there are some similarities with my PR. I think their suggestion to integrate with javax.validation.Validator is a great idea.

@wangmiscoding I agree to use jsr-303, I think using javax.validation for data validation is sufficient.
As a lightweight and efficient Excel parsing/importing tool, Fast-Excel should keep new features as simple as possible.

[wangmiscoding]

It seems there are some similarities with my PR. I think their suggestion to integrate with javax.validation.Validator is a great idea.
@wangmiscoding I agree to use jsr-303, I think using javax.validation for data validation is sufficient.
As a lightweight and efficient Excel parsing/importing tool, Fast-Excel should keep new features as simple as possible.

Yes, are you interested in completing this feature?

[AlchemyDing]

I can do it, if the community supports it

[wangmiscoding]

I can do it, if the community supports it如果社区支持，我可以做到

@delei Hi😊,What do you think?

[wangmiscoding]

@tianyufeng925 Perhaps we could collaborate?

[wangmiscoding]

#282

[tianyufeng925]

Hi @wangmiscoding! 👋

Thanks for reaching out! I just reviewed your PR #282 and I can see we're both working on validation capabilities for FastExcel - that's exciting!

What I noticed from your approach:

I see you've put a lot of thought into the validation framework integration. The javax.validation approach is definitely interesting and could provide a more standardized way to handle validations.

My current approach:

My PR focuses on a lightweight, FastExcel-native solution with:

• Simple @ExcelRequired annotation
• ExcelValidationUtils for batch validation
• Minimal dependencies and overhead

Potential collaboration ideas:

1. Complementary approaches: Your javax.validation integration could be the "advanced" validation layer, while mine provides the basic/lightweight option

2. Feature division:

   • You could focus on the javax.validation integration
   • I could continue with FastExcel-native annotations (dropdown, numeric, date validations)
   • Both approaches could coexist and serve different use cases

3. Unified solution: We could combine the best of both approaches into a comprehensive validation system

Questions for you:

1. What's your timeline for PR Added validation functionality when reading files, generating error messages based on validation results. Supports manually adding error messages #282?
2. Are you planning to cover all validation types (dropdown, numeric, date) or focusing on specific areas?
3. Would you be interested in a hybrid approach where we support both javax.validation and native FastExcel annotations?

I'm definitely open to collaboration! I think having multiple contributors working on validation will make the feature much stronger.

What do you think would be the best way to coordinate our efforts? 🤝

[wangmiscoding]

Hi @wangmiscoding! 👋  你好！👋

Thanks for reaching out! I just reviewed your PR #282 and I can see we're both working on validation capabilities for FastExcel - that's exciting!感谢您的联系！我刚刚查看了您的 PR #282 ，我可以看到我们都在开发 FastExcel 的验证功能 - 这很令人兴奋！

What I noticed from your approach:

我从你的方法中注意到：
I see you've put a lot of thought into the validation framework integration. The javax.validation approach is definitely interesting and could provide a more standardized way to handle validations.我看到你在验证框架集成上花了很多心思。javax.validation 方法绝对很有趣，可以提供一种更标准化的方式来处理验证。

My current approach:  我目前的方法：

My PR focuses on a lightweight, FastExcel-native solution with:我的 PR 专注于轻量级的 FastExcel 原生解决方案，具有：

• Simple @ExcelRequired annotation简单的 @ExcelRequired 注释
• ExcelValidationUtils for batch validationExcelValidationUtils 用于批量验证
• Minimal dependencies and overhead最小的依赖项和开销

Potential collaboration ideas:

潜在的合作想法：

1. Complementary approaches: Your javax.validation integration could be the "advanced" validation layer, while mine provides the basic/lightweight option补充**方法 **：您的 javax.validation 集成可以是“高级”验证层，而我的集成则提供基本/轻量级选项

2. Feature division:**功能划分 **：

   • You could focus on the javax.validation integration您可以专注于 javax.validation 集成
   • I could continue with FastExcel-native annotations (dropdown, numeric, date validations)我可以继续使用 FastExcel 原生注释（下拉列表、数字、日期验证）
   • Both approaches could coexist and serve different use cases这两种方法可以共存并服务于不同的用例

3. Unified solution: We could combine the best of both approaches into a comprehensive validation system**统一解决方案 **：我们可以将两种方法的优点结合到一个全面的验证系统中

Questions for you:  给你的问题：

1. What's your timeline for PR Added validation functionality when reading files, generating error messages based on validation results. Supports manually adding error messages #282?你们的公关时间表是怎样的？ Added validation functionality when reading files, generating error messages based on validation results. Supports manually adding error messages #282
2. Are you planning to cover all validation types (dropdown, numeric, date) or focusing on specific areas?您是否计划涵盖所有验证类型（下拉列表、数字、日期）或专注于特定区域？
3. Would you be interested in a hybrid approach where we support both javax.validation and native FastExcel annotations?您是否对我们同时支持 javax.validation 和原生 FastExcel 注释的混合方法感兴趣？

I'm definitely open to collaboration! I think having multiple contributors working on validation will make the feature much stronger.我绝对愿意合作！我认为让多个贡献者从事验证将使该功能更加强大。

What do you think would be the best way to coordinate our efforts? 🤝您认为协调我们努力的最佳方式是什么？🤝

Hello😊, sorry I’ve been a bit busy recently, but now I can start working on my tasks. I plan to improve the import validation feature. I’m going to use javax.validation.Validator for validation, so it will be enough to use native annotations like @NotNull, @notblank, etc.
Additionally, I plan to provide some default Converter implementations for error messages, and allow users to replace them with their own.
What do you think?

[delei]

Verification features are indeed what we need, and the community is willing to listen to more suggestions.

FYI, We are not in a hurry to decide how to implement them. Anyone with ideas is welcome to share them ,and provide as many specific implementation ideas as possible.

[tianyufeng925]

Thanks @delei! Really appreciate the support and the open approach to exploring different implementation ideas.

Since the community is interested, I'd love to gather more specific feedback:

For the community: What validation scenarios do you encounter most often in your Excel workflows?

• Required field validation?
• Dropdown selections?
• Numeric ranges?
• Date validations?
• Custom business rules?

Implementation preferences:

• Annotation-based (like my proposal)?
• Programmatic configuration?
• Integration with existing validation frameworks (like @wangmiscoding's javax.validation approach)?

I think having multiple implementation approaches could actually be a strength - different use cases might benefit from different approaches.

Looking forward to more community input!

[delei]

We plan to start incorporating it into the roadmap after the 1.3.0 release.If possible, please organise and describe the specific implementation approach, which can also be done in stages.

For example, how to support javax.validation.Validator, how to add or modify the existing API and etc.