String functions

For string processing, AQL offers the following functions:

CHAR_LENGTH()

CHAR_LENGTH(value) → length

Return the number of characters in value (not byte length).

Note: This functions returns the number of utf8 code points not the number of characters.

CONCAT()

CONCAT(value1, value2, ... valueN) → str

Concatenate the values passed as value1 to valueN.

  • values (any, repeatable): elements of arbitrary type (at least 1)
  • returns str (string): a concatenation of the elements. null values are ignored.
CONCAT("foo", "bar", "baz") // "foobarbaz"
CONCAT(1, 2, 3) // "123"
CONCAT("foo", [5, 6], {bar: "baz"}) // "foo[5,6]{\"bar\":\"baz\"}"

CONCAT(anyArray) → str

If a single array is passed to CONCAT(), its members are concatenated.

  • anyArray (array): array with elements of arbitrary type
  • returns str (string): a concatenation of the array elements. null values are ignored.
CONCAT( [ "foo", "bar", "baz" ] ) // "foobarbaz"
CONCAT( [1, 2, 3] ) // "123"

CONCAT_SEPARATOR()

CONCAT_SEPARATOR(separator, value1, value2, ... valueN) → joinedString

Concatenate the strings passed as arguments value1 to valueN using the separator string.

  • separator (string): an arbitrary separator string
  • values (string|array, repeatable): strings or arrays of strings as multiple arguments (at least 1)
  • returns joinedString (string): a concatenated string of the elements, using separator as separator string. null values are ignored. Array value arguments are expanded automatically, and their individual members will be concatenated. Nested arrays will be expanded too, but with their elements separated by commas if they have more than a single element.
CONCAT_SEPARATOR(", ", "foo", "bar", "baz")
// "foo, bar, baz"

CONCAT_SEPARATOR(", ", [ "foo", "bar", "baz" ])
// "foo, bar, baz"

CONCAT_SEPARATOR(", ", [ "foo", [ "b", "a", "r" ], "baz" ])
// [ "foo, b,a,r, baz" ]

CONCAT_SEPARATOR("-", [1, 2, 3, null], [4, null, 5])
// "1-2-3-4-5"

CONTAINS()

CONTAINS(text, search, returnIndex) → match

Check whether the string search is contained in the string text. The string matching performed by CONTAINS is case-sensitive.

  • text (string): the haystack
  • search (string): the needle
  • returnIndex (bool, optional): if set to true, the character position of the match is returned instead of a boolean. The default is false. The default is false.
  • returns match (bool|number): by default, true is returned if search is contained in text, and false otherwise. With returnIndex set to true, the position of the first occurrence of search within text is returned (starting at offset 0), or -1 if search is not contained in text.
CONTAINS("foobarbaz", "bar") // true
CONTAINS("foobarbaz", "horse") // false
CONTAINS("foobarbaz", "ba", true) // 3
CONTAINS("foobarbaz", "horse", true) // -1

COUNT()

This is an alias for LENGTH().

FIND_FIRST()

FIND_FIRST(text, search, start, end) → position

Return the position of the first occurrence of the string search inside the string text. Positions start at 0.

  • text (string): the haystack
  • search (string): the needle
  • start (number, optional): limit the search to a subset of the text, beginning at start
  • end (number, optional): limit the search to a subset of the text, ending at end
  • returns position (number): the character position of the match. If search is not contained in text, -1 is returned.
FIND_FIRST("foobarbaz", "ba") // 3
FIND_FIRST("foobarbaz", "ba", 4) // 6
FIND_FIRST("foobarbaz", "ba", 0, 3) // -1

FIND_LAST()

FIND_LAST(text, search, start, end) → position

Return the position of the last occurrence of the string search inside the string text. Positions start at 0.

  • text (string): the haystack
  • search (string): the needle
  • start (number, optional): limit the search to a subset of the text, beginning at start
  • end (number, optional): limit the search to a subset of the text, ending at end
  • returns position (number): the character position of the match. If search is not contained in text, -1 is returned.
FIND_LAST("foobarbaz", "ba") // 6
FIND_LAST("foobarbaz", "ba", 7) // -1
FIND_LAST("foobarbaz", "ba", 0, 4) // 3

JSON_PARSE()

JSON_PARSE(text) → value

Return an AQL value described by the JSON-encoded input string.

  • text (string): the string to parse as JSON
  • returns value (mixed): the value corresponding to the given JSON text. For input values that are no valid JSON strings, the function will return null.
JSON_PARSE("123") // 123
JSON_PARSE("[ true, false, 2 ]") // [ true, false, 2 ]
JSON_PARSE("\\\"abc\\\"") // "abc"
JSON_PARSE("{\\\"a\\\": 1}") // { a : 1 }
JSON_PARSE("abc") // null

JSON_STRINGIFY()

JSON_STRINGIFY(value) → text

Return a JSON string representation of the input value.

  • value (mixed): the value to convert to a JSON string
  • returns text (string): the JSON string representing value. For input values that cannot be converted to JSON, the function will return null.
JSON_STRINGIFY("1") // "1"
JSON_STRINGIFY("abc") // "\"abc\""
JSON_STRINGIFY("[1, 2, 3]") // "[1,2,3]"

LEFT()

LEFT(value, length) → substring

Return the length leftmost characters of the string value.

  • value (string): a string
  • length (number): how many characters to return
  • returns substring (string): at most length characters of value, starting on the left-hand side of the string
LEFT("foobar", 3) // "foo"
LEFT("foobar", 10) // "foobar"

LENGTH()

LENGTH(str) → length

Determine the character length of a string.

  • str (string): a string. If a number is passed, it will be casted to string first.
  • returns length (number): the character length of str (not byte length)
LENGTH("foobar") // 6
LENGTH("电脑坏了") // 4

LENGTH() can also determine the number of elements in an array, the number of attribute keys of an object / document and the amount of documents in a collection.

LIKE()

LIKE(text, search, caseInsensitive) → bool

Check whether the pattern search is contained in the string text, using wildcard matching.

  • text (string): the string to search in
  • search (string): a search pattern that can contain the wildcard characters % (meaning any sequence of characters, including none) and _ (any single character). Literal % and : must be escaped with two backslashes (four in arangosh). search cannot be a variable or a document attribute. The actual value must be present at query parse time already.
  • caseInsensitive (bool, optional): if set to true, the matching will be case-insensitive. The default is false.
  • returns bool (bool): true if the pattern is contained in text, and false otherwise
LIKE("cart", "ca_t")   // true
LIKE("carrot", "ca_t") // false
LIKE("carrot", "ca%t") // true

LIKE("foo bar baz", "bar")   // false
LIKE("foo bar baz", "%bar%") // true
LIKE("bar", "%bar%")         // true

LIKE("FoO bAr BaZ", "fOo%bAz")       // false
LIKE("FoO bAr BaZ", "fOo%bAz", true) // true

LOWER()

LOWER(value) → lowerCaseString

Convert upper-case letters in value to their lower-case counterparts. All other characters are returned unchanged.

  • value (string): a string
  • returns lowerCaseString (string): value with upper-case characters converted to lower-case characters

LTRIM()

LTRIM(value, chars) → strippedString

Return the string value with whitespace stripped from the start only.

  • value (string): a string
  • chars (string, optional): override the characters that should be removed from the string. It defaults to \r\n \t (i.e. 0x0d, 0x0a, 0x20 and 0x09).
  • returns strippedString (string): value without chars at the left-hand side
LTRIM("foo bar") // "foo bar"
LTRIM("  foo bar  ") // "foo bar  "
LTRIM("--==[foo-bar]==--", "-=[]") // "foo-bar]==--"

MD5()

MD5(text) → hash

Calculate the MD5 checksum for text and return it in a hexadecimal string representation.

  • text (string): a string
  • returns hash (string): MD5 checksum as hex string
MD5("foobar") // "3858f62230ac3c915f300c664312c63f"

RANDOM_TOKEN()

RANDOM_TOKEN(length) → randomString

Generate a pseudo-random token string with the specified length. The algorithm for token generation should be treated as opaque.

  • length (number): desired string length for the token. It must be greater than 0 and at most 65536.
  • returns randomString (string): a generated token consisting of lowercase letters, uppercase letters and numbers
RANDOM_TOKEN(8) // "zGl09z42"
RANDOM_TOKEN(8) // "m9w50Ft9"

REGEX_TEST()

REGEX_TEST(text, search, caseInsensitive) → bool

Check whether the pattern search is contained in the string text, using regular expression matching.

  • text (string): the string to search in
  • search (string): a regular expression search pattern
  • returns bool (bool): true if the pattern is contained in text, and false otherwise

The regular expression may consist of literal characters and the following characters and sequences:

  • . – the dot matches any single character except line terminators. To include line terminators, use [\s\S] instead to simulate . with DOTALL flag.
  • \d – matches a single digit, equivalent to [0-9]
  • \s – matches a single whitespace character
  • \S – matches a single non-whitespace character
  • \t – matches a tab character
  • \r – matches a carriage return
  • \n – matches a line-feed character
  • [xyz] – set of characters. matches any of the enclosed characters (i.e. x, y or z in this case
  • [^xyz] – negated set of characters. matches any other character than the enclosed ones (i.e. anything but x, y or z in this case)
  • [x-z] – range of characters. Matches any of the characters in the specified range, e.g. [0-9A-F] to match any character in 0123456789ABCDEF
  • [^x-z] – negated range of characters. Matches any other character than the ones specified in the range
  • (xyz) – defines and matches a pattern group
  • (x|y) – matches either x or y
  • ^ – matches the beginning of the string (e.g. ^xyz)
  • $ – matches the end of the string (e.g. xyz$)

Note that the characters ., *, ?, [, ], (, ), {, }, ^, and $ have a special meaning in regular expressions and may need to be escaped using a backslash, which requires escaping itself (\\). A literal backslash needs to be escaped using another escaped backslash, i.e. \\\\. In arangosh, the amount of backslashes needs to be doubled.

Characters and sequences may optionally be repeated using the following quantifiers:

  • x* – matches zero or more occurrences of x
  • x+ – matches one or more occurrences of x
  • x? – matches one or zero occurrences of x
  • x{y} – matches exactly y occurrences of x
  • x{y,z} – matches between y and z occurrences of x
  • x{y,} – matches at least y occurences of x

Note that xyz+ matches xyzzz, but if you want to match xyzxyz instead, you need to define a pattern group by wrapping the subexpression in parentheses and place the quantifier right behind it: (xyz)+.

If the regular expression in search is invalid, a warning will be raised and the function will return false.

REGEX_TEST("the quick brown fox", "the.*fox") // true
REGEX_TEST("the quick brown fox", "^(a|the)\s+(quick|slow).*f.x$") // true
REGEX_TEST("the\nquick\nbrown\nfox", "^the(\n[a-w]+)+\nfox$") // true

REVERSE()

REVERSE(value) → reversedString

Return the reverse of the string str.

  • value (string): a string
  • returns reversedString (string): a new string with the characters in reverse order
REVERSE("foobar") // "raboof"
REVERSE("电脑坏了") // "了坏脑电"

RIGHT(value, length) → substring

Return the length rightmost characters of the string value.

  • value (string): a string
  • length (number): how many characters to return
  • returns substring (string): at most length characters of value, starting on the right-hand side of the string
RIGHT("foobar", 3) // "bar"
RIGHT("foobar", 10) // "foobar"

RTRIM()

RTRIM(value, chars) → strippedString

Return the string value with whitespace stripped from the end only.

  • value (string): a string
  • chars (string, optional): override the characters that should be removed from the string. It defaults to \r\n \t (i.e. 0x0d, 0x0a, 0x20 and 0x09).
  • returns strippedString (string): value without chars at the right-hand side
RTRIM("foo bar") // "foo bar"
RTRIM("  foo bar  ") // "  foo bar"
RTRIM("--==[foo-bar]==--", "-=[]") // "--==[foo-bar"

SHA1()

SHA1(text) → hash

Calculate the SHA1 checksum for text and returns it in a hexadecimal string representation.

  • text (string): a string
  • returns hash (string): SHA1 checksum as hex string
SHA1("foobar") // "8843d7f92416211de9ebb963ff4ce28125932878"

SPLIT()

SPLIT(value, separator, limit) → strArray

Split the given string value into a list of strings, using the separator.

  • value (string): a string
  • separator (string): either a string or a list of strings. If separator is an empty string, value will be split into a list of characters. If no separator is specified, value will be returned as array.
  • limit (number, optional): limit the number of split values in the result. If no limit is given, the number of splits returned is not bounded.
  • returns strArray (array): an array of strings
SPLIT( "foo-bar-baz", "-" ) // [ "foo", "bar", "baz" ]
SPLIT( "foo-bar-baz", "-", 1 ) // [ "foo", "bar-baz" ]
SPLIT( "foo, bar & baz", [ ", ", " & " ] ) // [ "foo", "bar", "baz" ]

SUBSTITUTE()

SUBSTITUTE(value, search, replace, limit) → substitutedString

Replace search values in the string value.

  • value (string): a string
  • search (string|array): if search is a string, all occurrences of search will be replaced in value. If search is an array of strings, each occurrence of a value contained in search will be replaced by the corresponding array element in replace. If replace has less list items than search, occurrences of unmapped search items will be replaced by an empty string.
  • replace (string|array, optional): a replacement string, or an array of strings to replace the corresponding elements of search with. Can have less elements than search or be left out to remove matches. If search is an array but replace is a string, then all matches will be replaced with replace.
  • limit (number, optional): cap the number of replacements to this value
  • returns substitutedString (string): a new string with matches replaced (or removed)
SUBSTITUTE( "the quick brown foxx", "quick", "lazy" )
// "the lazy brown foxx"

SUBSTITUTE( "the quick brown foxx", [ "quick", "foxx" ], [ "slow", "dog" ] )
// "the slow brown dog"

SUBSTITUTE( "the quick brown foxx", [ "the", "foxx" ], [ "that", "dog" ], 1 )
//  "that quick brown foxx"

SUBSTITUTE( "the quick brown foxx", [ "the", "quick", "foxx" ], [ "A", "VOID!" ] )
// "A VOID! brown "

SUBSTITUTE( "the quick brown foxx", [ "quick", "foxx" ], "xx" )
// "the xx brown xx"

SUBSTITUTE(value, mapping, limit) → substitutedString

Alternatively, search and replace can be specified in a combined value.

  • value (string): a string
  • mapping (object): a lookup map with search strings as keys and replacement strings as values. Empty strings and null as values remove matches.
  • limit (number, optional): cap the number of replacements to this value
  • returns substitutedString (string): a new string with matches replaced (or removed)
SUBSTITUTE("the quick brown foxx", {
  "quick": "small",
  "brown": "slow",
  "foxx": "ant"
})
// "the small slow ant"

SUBSTITUTE("the quick brown foxx", { 
  "quick": "",
  "brown": null,
  "foxx": "ant"
})
// "the   ant"

SUBSTITUTE("the quick brown foxx", {
  "quick": "small",
  "brown": "slow",
  "foxx": "ant"
}, 2)
// "the small slow foxx"

SUBSTRING()

SUBSTRING(value, offset, length) → substring

Return a substring of value.

  • value (string): a string
  • offset (number): start at offset, offsets start at position 0
  • length (number, optional): at most length characters, omit to get the substring from offset to the end of the string
  • returns substring (string): a substring of value

TRIM()

TRIM(value, type) → strippedString

Return the string value with whitespace stripped from the start and/or end.

The optional type parameter specifies from which parts of the string the whitespace is stripped. LTRIM() and RTRIM() are preferred however.

  • value (string): a string
  • type (number, optional): strip whitespace from the
    • 0 – start and end of the string
    • 1 – start of the string only
    • 2 – end of the string only The default is 0.

TRIM(value, chars) → strippedString

Return the string value with whitespace stripped from the start and end.

  • value (string): a string
  • chars (string, optional): override the characters that should be removed from the string. It defaults to \r\n \t (i.e. 0x0d, 0x0a, 0x20 and 0x09).
  • returns strippedString (string): value without chars on both sides
TRIM("foo bar") // "foo bar"
TRIM("  foo bar  ") // "foo bar"
TRIM("--==[foo-bar]==--", "-=[]") // "foo-bar"  
TRIM("  foobar\t \r\n ") // "foobar"
TRIM(";foo;bar;baz, ", ",; ") // "foo;bar;baz"

UPPER()

UPPER(value) → upperCaseString

Convert lower-case letters in value to their upper-case counterparts. All other characters are returned unchanged.

  • value (string): a string
  • returns upperCaseString (string): value with lower-case characters converted to upper-case characters