Cloudera Docs

Evaluating Multiple Attributes

When it becomes necessary to evaluate the same conditions against multiple attributes, this can be accomplished by means of the and and or functions. However, this quickly becomes tedious, error-prone, and difficult to maintain. For this reason, NiFi provides several functions for evaluating the same conditions against groups of attributes at the same time.

anyAttribute

Description: Checks to see if any of the given attributes, match the given condition. This function has no subject and takes one or more arguments that are the names of attributes to which the remainder of the Expression is to be applied. If any of the attributes specified, when evaluated against the rest of the Expression, returns a value of true, then this function will return true. Otherwise, this function will return false.

Subject Type: No Subject

Arguments:

  • Attribute Names : One or more attribute names to evaluate

Return Type: Boolean

Examples: Given that the "abc" attribute contains the value "hello world", "xyz" contains "good bye world", and "filename" contains "file.txt" consider the following examples:

Table 1. Table 28. anyAttribute Examples
Expression Value
${anyAttribute("abc", "xyz"):contains("bye")} true
${anyAttribute("filename","xyz"):toUpper():contains("e")} false

allAttributes

Description: Checks to see if all of the given attributes match the given condition. This function has no subject and takes one or more arguments that are the names of attributes to which the remainder of the Expression is to be applied. If all of the attributes specified, when evaluated against the rest of the Expression, returns a value of true, then this function will return true. Otherwise, this function will return false.

Subject Type: No Subject

Arguments:

  • Attribute Names : One or more attribute names to evaluate

Return Type: Boolean

Examples: Given that the "abc" attribute contains the value "hello world", "xyz" contains "good bye world", and "filename" contains "file.txt" consider the following examples:

Table 2. Table 29. allAttributes Example
Expression Value
${allAttributes("abc", "xyz"):contains("world")} true 
${allAttributes("abc",
                "filename","xyz"):toUpper():contains("e")}
 false

anyMatchingAttribute

Description: Checks to see if any of the given attributes, match the given condition. This function has no subject and takes one or more arguments that are Regular Expressions to match against attribute names. Any attribute whose name matches one of the supplied Regular Expressions will be evaluated against the rest of the Expression. If any of the attributes specified, when evaluated against the rest of the Expression, returns a value of true, then this function will return true. Otherwise, this function will return false.

Subject Type: No Subject

Arguments:

  • Regex : One or more Regular Expressions (in the Java Pattern syntax) to evaluate against attribute names

Return Type: Boolean

Examples: Given that the "abc" attribute contains the value "hello world", "xyz" contains "good bye world", and "filename" contains "file.txt" consider the following examples:

Table 3. Table 30. anyMatchingAttribute Example
Expression Value
${anyMatchingAttribute("[ax].*"):contains('bye')} true
${anyMatchingAttribute(".*"):isNull()} false

allMatchingAttributes

Description: Checks to see if any of the given attributes, match the given condition. This function has no subject and takes one or more arguments that are Regular Expressions to match against attribute names. Any attribute whose name matches one of the supplied Regular Expressions will be evaluated against the rest of the Expression. If all of the attributes specified, when evaluated against the rest of the Expression, return a value of true, then this function will return true. Otherwise, this function will return false.

Subject Type: No Subject

  • Regex : One or more Regular Expressions (in the Java Pattern syntax) to evaluate against attribute names

Return Type: Boolean

Examples: Given that the "abc" attribute contains the value "hello world", "xyz" contains "good bye world", and "filename" contains "file.txt" consider the following examples:

Table 4. Table 31. anyMatchingAttributes Examples
Expression Value
${allMatchingAttributes("[ax].*"):contains("world")} true
${allMatchingAttributes(".*"):isNull()} false
${allMatchingAttributes("f.*"):count()} 1

anyDelineatedValue

Description: Splits a String apart according to a delimiter that is provided, and then evaluates each of the values against the rest of the Expression. If the Expression, when evaluated against any of the individual values, returns true, this function returns true. Otherwise, the function returns false.

Subject Type: No Subject

Arguments:

  • Delineated Value : The value that is delineated. This is generally an embedded Expression, though it does not have to be.

  • Delimiter : The value to use to split apart the delineatedValue argument.

Return Type: Boolean

Examples: Given that the "number_list" attribute contains the value "1,2,3,4,5", and the "word_list" attribute contains the value "the,and,or,not", consider the following examples:

Table 5. Table 32. anyDelineatedValue Examples
Expression Value
${anyDelineatedValue("${number_list}", ","):contains("5")} true 
${anyDelineatedValue("this that and",
                ","):equals("${word_list}")}
 false

allDelineatedValues

Description: Splits a String apart according to a delimiter that is provided, and then evaluates each of the values against the rest of the Expression. If the Expression, when evaluated against all of the individual values, returns true in each case, then this function returns true. Otherwise, the function returns false.

Subject Type: No Subject

Arguments:

  • Delineated Value : The value that is delineated. This is generally an embedded Expression, though it does not have to be.

  • Delimiter : The value to use to split apart the delineatedValue argument.

Return Type: Boolean

Examples: Given that the "number_list" attribute contains the value "1,2,3,4,5", and the "word_list" attribute contains the value "those,known,or,not", consider the following examples:

Table 6. Table 33. allDelineatedValues Examples
Expression Value
${allDelineatedValues("${word_list}", ","):contains("o")} true
${allDelineatedValues("${number_list}", ","):count()} 5 
${allDelineatedValues("${number_list}",
              ","):matches("[0-9]+")}
 true
${allDelineatedValues("${word_list}", ","):matches('e')} false

join

Description: Aggregate function that concatenates multiple values with the specified delimiter. This function may be used only in conjunction with the allAttributes, allMatchingAttributes, and allDelineatedValues functions.

Subject Type: String

Arguments:

  • Delimiter : The String delimiter to use when joining values

Return Type: String

Examples: Given that the "abc" attribute contains the value "hello world", "xyz" contains "good bye world", and "filename" contains "file.txt" consider the following examples:

Table 7. Table 34. join Examples
Expression Value 
${allMatchingAttributes("[ax].*"):substringBefore("
                "):join("-")}
 hello-good
${allAttributes("abc", "xyz"):join(" now")} hello world nowgood bye world now

count

Description: Aggregate function that counts the number of non-null, non-false values returned by the allAttributes, allMatchingAttributes, and allDelineatedValues. This function may be used only in conjunction with the allAttributes, allMatchingAttributes, and allDelineatedValues functions.

Subject Type: Any

Arguments: No arguments

Return Type: Number

Examples: Given that the "abc" attribute contains the value "hello world", "xyz" contains "good bye world", and "number_list" contains "1,2,3,4,5" consider the following examples:

Table 8. Table 35. count Examples
Expression Value 
${allMatchingAttributes("[ax].*"):substringBefore("
              "):count()}
 2
${allAttributes("abc", "xyz"):contains("world"):count()} 1
${allDelineatedValues(${number_list}, ","):count()} 5
${allAttributes("abc", "non-existent-attr", "xyz"):count()} 2
${allMatchingAttributes(".*"):length():gt(10):count()} 2