CODEWITHSUNDEEP
javaregexjsfbean-validation
sotn
sotn

Reputation: 2101

How to skip @Pattern validation on a blank field?

I am using JSR303 bean validation annotations in my JSF managed bean to validate text input. Here are the annotations:

@Size(min=0, max=20, message = "Value cannot be more than 20 characters")
@Pattern(regexp = "[^|]", message = "Invalid entry. See field description.")  
private String txt;

The @Pattern annotation throws an error when a pipe character is found in the string. But when a user leaves the field blank and clicks submit, the error is also thrown. Why is this happening when the field is blank?

Upvotes: 1

Views: 3719

Answers (1)

palacsint
palacsint

Reputation: 28885

Because the regexp [^|] needs exactly one character to match. You should use a quantifier: [^|]*

Here are some tests:

System.out.println(Pattern.matches("[^|]", "")); // false
System.out.println(Pattern.matches("[^|]", "a")); // true
System.out.println(Pattern.matches("[^|]", "aaa")); // false
System.out.println(Pattern.matches("[^|]*", "")); // true
System.out.println(Pattern.matches("[^|]*", "aaa")); // true
System.out.println(Pattern.matches("[^|]*", "a|a")); // false

Upvotes: 4

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