NiFi record path expression

Use this information to understand the different expressions that are available, what they do, and how they work.

Expressions can be divided into two groups.

Target expressions, which produce value that can be assigned to target field, such as substringAfter( /name, ' ' ). A target expression can also be used within a filter but does not return a boolean (true or false value) and therefore cannot itself be an entire filter. For example, you can use a path such as [ substringAfter(/name, ' ') = 'Doe'] but you cannot use [ substringAfter(/name, ' ') ] because doing so doesn’t really make sense, as filters must be boolean values.
Filter expressions, which are to be used as a filter, such as [ contains(/name,'John') ].

Standalone functions

Function name	Description
`substring`	`substring(value (expression), start index (int), end index (int))`. The substring function returns a portion of a String value. The function requires 3 arguments; the value to take a portion of, the 0-based start index (inclusive), and the 0-based end index (exclusive). The start index and end index can be 0 to indicate the first character of a String, a positive integer to indicate the nth index into the string, or a negative integer. If the value is a negative integer, say -n, then this represents the nth character for the end. A value of-1 indicates the last character in the String. For example, `substring( 'hello world', 0, -1 )` means to take the string hello, and return characters 0 through the last character, so the return value is hello world.
`substringAfter`	Expression function `substringAfter(value (expression), pattern (literal))`. Returns the portion of a String value that occurs after the first occurrence of some other value.
`substringAfterLast`	expression function `substringAfterLast(value (expression), pattern (literal))`. Returns the portion of a String value that occurs after the last occurrence of some other value.
`substringBefore`	expression function `substringBefore(value (expression), pattern (literal))`, pattern (literal)). Returns the portion of a String value that occurs before the first occurrence of some other value.
`substringBeforelLast`	Expression function `substringBeforeLast(value (expression), pattern (literal))`. Returns the portion of a String value that occurs before the last occurrence of some other value.
`replace`	Expression function `replace(value (expression), pattern (literal), replace (literal))`. Replaces all occurrences of a String with another String.
`replaceRegex`	Expression function `replaceRegex(value (expression), pattern (regex), replace (literal))`. Evaluates a Regular Expression against the contents of a String value and replaces any match with another value. This function requires 3 arguments; the String to run the regular expression against, the regular expression to run, and the replacement value. The replacement value may optionally use back-references, such as $1.
`concat`	Expression function `concat(value (expression), ...)`. Concatenates all the arguments together.
`fieldName`	Expression function `fieldName(value (expression)`. Normally, when a path is given to a particular field in a Record, what is returned is the value of that field. It can sometimes be useful, however, to obtain the name of the field instead of the value. To do this, we can use the fieldName function.
`toDate`	Expression function `toDate(value (expression), format (literal), zone (literal))`. Converts a String to a date.
`toString`	Expression function `toString(value (expression), encoding (literal))`. Converts a value to a String, using the given character set if the input type is "bytes"
`toBytes`	Expression function `toBytes(value (expression), encoding (literal))`. Converts a String to byte[], using the given character set.
`coalesce`	Expression function `coalesce(value (expression), ...)`. Returns the first value from the given arguments that is non-null.
`format`	Expression function `format(value (expression), format (literal), zone (literal))`. Converts a Date to a String in the given format with an optional time zone.
`trim`	Expression function `trim(value (expression))`. Removes whitespace from the start and end of a string.
`toUpperCase`	Expression function `toUpperCase(value (expression))`. Change the entire String to upper case.
`toLowerCase`	Expression function `toLowerCase(value (expression))`. Changes the entire string to lower case.
`base64Encode`	Expression function `base64Encode(value (expression))`. Converts a String using Base64 encoding, using the UTF-8 character set.
`base64Decode`	Expression function `base64Decode(value (expression))`. Decodes a Base64-encoded String.
`escapeJson`	Expression function `escapeJson(value (expression))`. JSON Stringifies a Record, Array or simple field (e.g. String), using the UTF-8 character set.
`unescapeJson`	Expression function `unescapeJson(value (expression))`. Converts a stringified JSON element to a Record, Array or simple field (e.g. String), using the UTF-8 character set.
`hash`	Expression function `hash(value (expression), algorithm (literal))`. Converts a String using a hash algorithm (HA-384, SHA-224, SHA-256, MD2, SHA, SHA-512, MD5).
`padLeft`	Expression function `padLeft(value (expression), length (int), pad (literal))`. Prepends characters to the input String until it reaches the desired length.
`padRight`	Expression function `padRight(value (expression), length (int), pad (literal))`. Appends characters to the input String until it reaches the desired length.
`uuid5`	Expression function `uuid5(value (expression), namespace (expression))`. Inserts a UUID v5 into the target field.
`zipValue`	Expression function `zipValue(key (expression), value (expression), field (literal), delimiter (literal))`. zip key string and value strings and get value for given field name using given delimiter.
`delimitedField`	Expression function `delimitedField(value (expression), index (literal number), delimiter(literal))`. Splits value by delimiter if given, otherwise by spaces and get field value at index.
`csvLookup`	Expression function `csvLookup(lookupName (literal), key (expression), default (expression))`. Returns look up value from CSV. Currently, only default value is used and the the actual lookup should be directly implemented in NiFi common template.
`path`	Expression function (/)
`property`	Expression function (without prefix slash or surrounded qoutes)
`identifier`	Expression function internal
`literalString`	Expression function (surrounded by quotes)
`literalNumber`	Expression function (value number including decimal and scientific numbers)

Filter functions

Function name	Description
`equal`	conditional filter (=)
`notEqual`	Conditional filter (!=)
`greater`	Conditional filter (>)
`greaterAndEqual`	Conditional filter (>=)
`lesser`	Conditional filter (<)
`lesserAndEqual`	Conditional filter (<=)
`contains`	Conditional filter `contains(value (expression), pattern (literal))`. Returns true if a string value contains the provided substring, false otherwise.
`matchesRegex`	Conditional filter `matchesRegex(value (expression), pattern (regex))`. Evaluates a Regular Expression against the contents of a string value and returns true if the Regular Expression exactly matches the String value, false otherwise.
`startsWith`	Conditional filter `startsWith(value (expression), pattern (literal))`. Returns true if a string value starts with the provided substring, false otherwise.
`endsWith`	Conditional filter `endsWith(value (expression), pattern (literal))`. Returns true if a string value ends with the provided substring, false otherwise.
`not`	Conditional filter `not(value (condition))`. Inverts the value of the function or expression that is passed into the not function.
`isEmpty`	Conditional filter `isEmpty(value (expression))`. Returns true if the provided value is either null or is an empty string.
`isBlank`	Conditional filter `isBlank(value (expression))`. Returns true if the provided value is either null or is an empty string or a string that consists only of white space (spaces, tabs, carriage returns, and new-line characters).
`zipContains`	Conditional filter `zipContains(key (expression), value (expression), field (literal), delimiter (literal))`. zip key string and value strings and test if it contains given field name using given delimiter.