CODEWITHSUNDEEP
schemaietf-netmod-yangyang
Olumide
Olumide

Reputation: 5819

Default string values for union types in Yang Schema

Why can't the leaf wibble be assigned a default value "-"in the following schema (comments not in schema, added to post for clarity)

module type
{
    namespace "example.com";
    prefix "foo";
    
    typedef optional-value {
        type  union {
            type uint8 {
                range "0 .. 99";
            }
            
            type string {
                pattern "^-$";
            }
        }
    }
    
    container bar {
        leaf wibble {
            type optional-value;
            default "-"; ### NOT OKAY
        }
        
        leaf wobble {
            type optional-value;
            default 42;  ### OKAY
        }
    }
}

yanglint (version 0.16.105) does not validate the above schema and returns the error message:

err : Invalid value "-" in "wibble" element. (/type:wibble)
err : Module "type" parsing failed.

Done some more experimenting and it appears that strings with patterns cannot be assigned default values

module tmp
{
    namespace "example.com";
    prefix "foo";
    
    container bar {
        leaf wibble {
            type string {
                pattern "^x$";
            }
            default "x";    ### NOT OKAY
        }
        
        leaf wobble {
            type string;
            default "y";    ### OKAY
        }
    }
}

yanglint output:

err : Value "x" does not satisfy the constraint "^x$" (range, length, or pattern). (/tmp:wibble)
err : Module "tmp" parsing failed.

Upvotes: 0

Views: 955

Answers (1)

Piotr Babij
Piotr Babij

Reputation: 927

In YANG one uses the regex flavor from XML Schema which doesn't require ^$ to anchor expressions so that they math the entire value. All XSD expressions are implicitly anchored. You could try to remove these characters from your patterns and give it another try.

Upvotes: 1

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