README
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Validation Package
Overview
The validation package provides utilities for validating data in Go applications. It offers a structured way to perform validations, collect validation errors, and report them in a consistent format. This package is useful for validating user input, request data, or any other data that needs to conform to certain rules or constraints.
Features
- Structured Validation: Collect and report validation errors in a structured way
- Common Validators: Built-in validators for common validation scenarios
- Generic Support: Type-safe validation with Go generics
- Composable Validation: Combine multiple validators for complex validation rules
- Field-Level Validation: Validate individual fields with specific error messages
- Collection Validation: Validate all items in a collection
Installation
go get github.com/abitofhelp/servicelib/validation
Quick Start
See the Basic Validation Example for a complete, runnable example of how to use the validation package.
Configuration
The validation package does not require any specific configuration. It can be used directly without any setup.
API Documentation
Core Types
ValidationResult
The ValidationResult struct is the main entry point for the validation package. It provides methods for collecting and reporting validation errors.
See the Basic Validation Example for a complete, runnable example of how to use the ValidationResult struct.
ValidationError
The ValidationError struct represents a validation error with a message and a field name.
Key Methods
NewValidationResult
The NewValidationResult function creates a new validation result.
AddError
The AddError method adds an error to the validation result.
IsValid
The IsValid method checks if the validation result is valid (has no errors).
Error
The Error method returns an error if the validation result is not valid.
Common Validators
The validation package provides several common validators:
Required: Validates that a value is not emptyMinLength: Validates that a string has a minimum lengthMaxLength: Validates that a string has a maximum lengthPattern: Validates that a string matches a regular expression patternPastDate: Validates that a date is in the pastValidDateRange: Validates that a date range is validValidateID: Validates that an ID is validAllTrue: Validates that all items in a collection satisfy a conditionValidateAll: Validates all items in a collection
See the Date Validation Example for a complete, runnable example of how to use date validators.
Examples
For complete, runnable examples, see the following files in the examples directory:
- Basic Validation Example - Shows how to use basic validators
- Collection Validation Example - Shows how to validate collections
- Custom Validation Example - Shows how to create custom validators
- Date Validation Example - Shows how to validate dates
Best Practices
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Create a Validation Result Early: Create a validation result at the beginning of your validation function and pass it to all validators.
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Use Field Names Consistently: Use consistent field names across your application to make error messages more understandable.
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Combine Validators: Combine multiple validators for complex validation rules.
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Validate Collections Properly: Use ValidateAll for collections where each item needs validation.
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Return Early for Critical Validations: For performance reasons, return early if critical validations fail.
See the Custom Validation Example for a complete, runnable example of how to implement these best practices.
Troubleshooting
Common Issues
Validation Errors Not Being Reported
Issue: Validation errors are not being reported even though validation is failing.
Solution: Ensure that you are checking the result of IsValid() or using the Error() method to get the validation errors.
Inconsistent Error Messages
Issue: Error messages are inconsistent or not descriptive enough.
Solution: Use consistent field names and descriptive error messages. Consider creating custom validators for complex validation rules.
Performance Issues with Large Collections
Issue: Validation is slow for large collections.
Solution: Consider validating only a subset of the collection or implementing pagination. For critical validations, return early if they fail.
Related Components
- Errors - The errors component is used by the validation package for error handling.
- Context - The context component can be used with the validation package for context-aware validation.
- Logging - The logging component can be used with the validation package for logging validation errors.
Contributing
Contributions to this component are welcome! Please see the Contributing Guide for more information.
License
This project is licensed under the MIT License - see the LICENSE file for details.
Documentation
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Index ¶
- func AllTrue[T any](items []T, predicate func(T) bool) bool
- func MaxLength(value string, max int, field string, result *ValidationResult)
- func MinLength(value string, min int, field string, result *ValidationResult)
- func PastDate(value time.Time, field string, result *ValidationResult)
- func Pattern(value, pattern, field string, result *ValidationResult)
- func Required(value, field string, result *ValidationResult)
- func ValidDateRange(start, end time.Time, startField, endField string, result *ValidationResult)
- func ValidateAll[T any](items []T, validator func(T, int, *ValidationResult), result *ValidationResult)
- func ValidateID(id, field string, result *ValidationResult)
- type ValidationResult
Constants ¶
This section is empty.
Variables ¶
This section is empty.
Functions ¶
func MaxLength ¶
func MaxLength(value string, max int, field string, result *ValidationResult)
MaxLength validates that a string has a maximum length
func MinLength ¶
func MinLength(value string, min int, field string, result *ValidationResult)
MinLength validates that a string has a minimum length
func PastDate ¶
func PastDate(value time.Time, field string, result *ValidationResult)
PastDate validates that a date is in the past
func Pattern ¶
func Pattern(value, pattern, field string, result *ValidationResult)
Pattern validates that a string matches a regular expression
func Required ¶
func Required(value, field string, result *ValidationResult)
Required validates that a string is not empty
func ValidDateRange ¶
func ValidDateRange(start, end time.Time, startField, endField string, result *ValidationResult)
ValidDateRange validates that a start date is before an end date
func ValidateAll ¶
func ValidateAll[T any](items []T, validator func(T, int, *ValidationResult), result *ValidationResult)
ValidateAll validates all items in a slice
func ValidateID ¶
func ValidateID(id, field string, result *ValidationResult)
ValidateID validates that an ID is not empty
Types ¶
type ValidationResult ¶
type ValidationResult struct {
// contains filtered or unexported fields
}
ValidationResult holds the result of a validation operation
func NewValidationResult ¶
func NewValidationResult() *ValidationResult
NewValidationResult creates a new ValidationResult
func (*ValidationResult) AddError ¶
func (v *ValidationResult) AddError(msg, field string)
AddError adds an error to the validation result
func (*ValidationResult) Error ¶
func (v *ValidationResult) Error() error
Error returns the validation errors as an error
func (*ValidationResult) IsValid ¶
func (v *ValidationResult) IsValid() bool
IsValid returns true if there are no validation errors
Source Files