String Extension

This extension provides basic string handling capabilities such as con-cat, length, convert to lowercase, replace all, etc. String extension can be used in a query as follows. Following are the functions of the String extension.

Char At function

Syntax	`<string> str:charAt(<string> str, <int> index)`
Extension Type	Function
Description	Returns the char value as a string value at the specified index.
Example	`charAt("WSO2", 1)` returns `'S'`.

Coalesce function

Syntax	`< int\|long\|float\|double\|string\|boolean > str: coalesce (< int\|long\|float\|double\|string\|boolean > arg1, < int\|long\|float\|double\|string\|boolean > arg2 ,.., < int\|long\|float\|double\|string\|boolean > argN )`
Extension Type	Function
Description	Returns the value of the first of its input parameters that is not null.
Parameters	This functions accepts any number of parameters. The parameters can be of different types.
Return Type	This is the same as the type of the first input parameter that is not null.
Examples	`coalesce("123", null, "789")` returns `"123"`. `coalesce(null, "BBB", "CCC")` returns `"BBB"`. `coalesce(null, null, null)` returns `null`.

Concatenation function

Syntax	`<string> str: concat ( <int\|long\|float\|double\|string\|boolean > arg1, < int\|long\|float\|double\|string\|boolean > arg2 ,.., < int\|long\|float\|double\|string\|boolean > argN )`
Extension Type	Function
Description	Returns a string that is the result of concatenating the given arguments: `arg1` , `arg2` , .., `argN` .
Examples	`concat("D533", "8JU^", "XYZ")` returns `"D5338JU^XYZ"`. `concat("AAA", null, "CCC")` returns `"AAACCC"`.

Contains function

Syntax	`<bool> str: contains ( < string> inputSequence, <string> searchingSequence )`
Extension Type	Function
Description	This method returns `true` if `inputSequence` contains the specified sequence of char values in the `searchingSequence` .
Example	`contains("21 products are produced by WSO2 currently", "WSO2")` returns `true`.

Hexadecimal function

Syntax	`<string> str: hex ( < string> str)`
Extension Type	Function
Description	Returns a hexadecimal string representation of `str` .
Example	`hex("MySQL")` returns `"4d7953514c"`.

Length function

Syntax	`<int> str: length ( < string> str)`
Extension Type	Function
Description	Returns the length of the string: `str` .
Examples	`length("Hello World")` returns `11`.

Lower Case function

Syntax	`<string> str: lower ( < string> str)`
Extension Type	Function
Description	Converts the capital letters in the `str` input string to the equivalent simple letters.
Example	`lower("WSO2 cep ")` returns `"wso2 cep "`.

Regular Expression function

Syntax	`<boolean> str: regexp ( < string> str, <string> regex )`
Extension Type	Function
Description	Returns `true` if the given string (i.e. `str` `)` matches the given regular expression (i.e. `regex` ). Returns `false` if the string does not match the regular expression.
Example	`regexp("WSO2 abcdh", "WSO(.*h)")` returns `true`.

Repeat function

Syntax	`<string> str: repeat ( < string> str, <int> times)`
Extension Type	Function
Description	Repeats the specified string (i.e. `string` ) for the specified number of times (i.e. `times` ).
Example	`repeat("StRing 1", 3)` returns `"StRing 1StRing 1StRing 1"`.

Replace All function

Syntax	`<string> str: replaceAll ( < string> str, <string> regex , <string> replacement)`
Extension Type	Function
Description	Replaces each substring of the given string (i.e. `str` ) that matches the given regular expression (i.e. `regex` ) with the string specified as the replacement (i.e. `replacement` ).
Example	`replaceAll("hello hi hello", 'hello', 'test')` returns `"test hi test"`.

Replace First function

Syntax	`<string> str: replaceFirst (< string> str , <string> regex , <string> replacement )`
Extension Type	Function
Description	Replaces the first substring that matches the given regular expression (i.e. `regex`) with the string specified as the replacement (i.e. `replacement`)
Example	`replaceFirst("hello WSO2 A hello", 'WSO2(.*)A', 'XXXX')` returns `"hello XXXX hello"`.

Reverse function

Syntax	`<string> str: reverse ( < string> str)`
Extension Type	Function
Description	Returns the reverse ordered string of `str` .
Example	`reverse("Hello World")` returns `"dlroW olleH"`.

Split function

Syntax	`<string> str: split ( <string> sourceString, <string> splitCharacter, <int> returnedOutputPosition )`
Extension Type	Function
Description	This method splits the given `sourceString` by given `splitCharacter` and returns the string in the index given by `returnedOutputPosition` .
Example	`split("WSO2,ABM,NSFT", ",", 0)` returns `WSO2`.

String Compare function

Syntax	`<int> str: strcmp ( < string> str, <string> compareTo)`
Extension Type	Function
Description	Compares `str` with `compareTo` strings lexicographically.
Examples	`strcmp("Hello", 'Hello')` returns `0`. `strcmp("AbCDefghiJ KLMN", 'Hello')` returns `-7`.

Sub String function

Syntax	`<string> str: substr ( < string> sourceText, <int> beginIndex )`
Extension Type	Function
Description	Returns a ne string that is a substring of `sourceText.`
Example	`substr("AbCDefghiJ KLMN", 4)` returns `"efghiJ KLMN"`.

Syntax	`<string> str: substr ( < string> sourceText, <int> beginIndex, <int> length )`
Extension Type	Function
Description	Returns a new string that is a substring of `sourceText`.
Example	`substr("AbCDefghiJ KLMN", 2, 4)` returns `"CDef"`.

Syntax	`<string> str: substr ( < string> sourceText, <string> regex)`
Extension Type	Function
Description	Returns a new string that is a substring of `sourceText`.
Examples	`substr("WSO2D efghiJ KLMN", '^WSO2(.*)')` returns `"WSO2D efghiJ KLMN"`.

Syntax	`<string> str: substr ( < string> sourceText, <string> regex, <int> groupNumber )`
Extension Type	Function
Description	Returns a new string that is a substring of `sourceText`.
Example	`substr("WSO2 cep WSO2 XX E hi hA WSO2 heAllo", 'WSO2(.)A(.)', 2)` returns `" ello"`.

Trim function

Syntax	`<string> str: trim ( < string> str)`
Extension Type	Function
Description	Returns a copy of `str` , with the leading and/or trailing white-spaces omitted.
Example	`trim(" AbCDefghiJ KLMN ")` returns `"AbCDefghiJ KLMN"`.

Unhexadecimal function

Syntax	`<string> str: unhex ( < string> str)`
Extension Type	Function
Description	This is the equivalent of the `unhex` function in mysql 5.0. `unhex(str)` interprets each pair of characters in `str` as a hexadecimal number. Also see hex () string extension.
Example	`unhex("4d7953514c")` returns `"MySQL"`.

Upper Case function

Syntax	`<string> str: upper ( <string> str)`
Extension Type	Function
Description	Converts the simple letters in the given input string (i.e. `str` ) to the equivalent capital letters.
Example	`upper("Hello World")` returns `"HELLO WORLD"`.