jep-data-extension is a project that extends JEP, the powerful mathematical expression parser and evaluator for Java, introducing data manipulation capabilities with custom functions and operators ready to use, including RegEx, XPath, JSONPath and Web Services.
For details about JEP core features, access JEP documentation.
Package | Name | Description |
---|---|---|
String functions | camel | Converts a string to camel case |
concat | Concatenates the arguments into a string. | |
endsWith | Returns 1 (true) if a string ends with the specified suffix. | |
findMatch | Returns the first match of the given regular expression found inside a string. | |
findMatches | Returns a list containing all matches of the given regular expression inside a string. | |
formatString | Returns a formatted string according to given pattern and variable arguments. | |
lpad/leftPad | Left-pads a string to a given size. | |
lcase/lower | Converts a text string to all lower-case letters. | |
matches | Returns a 1 if the given string contains at least one match of a given RegEx. | |
normalizeString | Normalizes a Unicode string, replacing accents and other diacritics with ASCII chars. | |
proper | Converts a string to proper case, i.e., only the first letter in each word in upper-case. | |
replace | Replaces all occurrences of a given string with another one. | |
replaceRegex | Replaces all matches of a given regular expression. | |
rpad/rightPad | Right-pads a string to a given size. | |
split | Splits a string into a string array based on a separating string or regular expression. | |
startsWith | Returns 1 if a string starts a given prefix. | |
trim | Removes leading and trailing spaces. | |
ucase/upper | Converts a text string to all upper-case letters. | |
Date functions | now/sysdate | Returns the system's current date & time. |
str2date | Converts a string into date by trying different patterns such as RFC-3339, RFC-822 and common ISO-8601 variations. | |
date2str | Converts a date into string using a specified format. | |
daysBetween | Returns the number of days between two dates. | |
endOfMonth | Returns a date corresponding to the last day of the month given a source date. | |
isLeapYear | Returns 1 if the given date or year number is a leap year, i.e., an year with 366 days. | |
year | Returns the year for a given date. | |
quarter | Returns the quarter of the year for a given date. | |
month | Returns the month for a given date, a number starting from 1 (Jan) to 12 (Dec). | |
isoWeekNumber | Returns the ISO week number for a given date. | |
weekday | Returns the day of the week of a date, a number from 1 (Sunday) to 7 (Saturday). | |
day | Returns the day of the month for a given date.. | |
hour | Returns the hour of day for a given date, as a number from 0 (12AM) to 23 (11PM). | |
minute | Returns the minute within the hour for a given date, as a number from 0 to 59. | |
second | Returns the seconds within the minute for a given date, a number from 0 to 59. | |
addDays | Returns the result from adding a number of days to a date. | |
Math functions | arabic | Converts a Roman numeral to Arabic. |
roman | Converts an Arabic numeral to Roman. | |
Data manipulation & filtering | xpath | Returns the result of the given XPath expression at the specified XML. |
jsonpath | Returns the result of the given JSONPath expression at the specified JSON. | |
Statistical functions | average | Returns the average of the elements inside a given array, JSON array or collection (including valid representations). |
count | Returns the number of elements inside a given array, JSON array or collection (including valid string representations). | |
max | Returns the largest value in a given array, JSON array or collection (including valid string representations). | |
min | Returns the smallest value in a given array, JSON array or collection (including valid string representations). | |
Random | uuid | Produces a randomly generated type 4 UUID (Universally-unique Identifier) string. |
Utility functions | distinct | Returns a list consisting of the distinct elements of a given list, array or JSON array. |
getEnv | Returns the value of an environment variable. | |
getSystemProperty | Returns the value of system property. | |
isDecimal | Returns 1 if the given parameter is a number (including strings) containing decimals. | |
isEmpty | Returns 1 if a given parameter is either null or an empty String, JSON or collection. | |
isInteger | Returns 1 if the given number (or valid string) represents a whole number, i.e, which lacks decimals. | |
readFile | Returns the content of a text file in the file system. | |
typeOf/class | Returns the Java type associated with the given variable. | |
Cryptography functions | sha256 | Computes the SHA-256 hash of the given string and transforms the binary result into a hexadecimal string. |
toBase64 | Encodes a string to Base64 encoding scheme. | |
fromBase64 | Decodes a Base64 encoded string. | |
Web Services | httpGet | Returns data from a Web Service or RESTful API, as string. |
http | Invokes a specific method towards a Web Service/REST API. | |
httpHeader | This function groups a variable number of HTTP header entries for usage with other HTTP functions. | |
basicAuthorizationHeader | Generates a basic authorization header from a given username and password. | |
httpStatusCode | Returns the HTTP status code of a given WebServiceResponse. | |
httpResponse | Returns the HTTP response body from given WebServiceResponse, as string. |
âšī¸ Find examples in the wiki.
JEP offers a good set of operators for common arithmetic and logical operations, for example: addition (+
), subtraction (-
), multiplication (*
), division (/
), modulus (%
), power (^
), "Boolean And" (&&
), "Boolean Or" (||
), and "Boolean Not" (!
). These operators can be used when required and are supported by JEP.
Standard JEP relational operators accept only numerical variables (including string representation of non-complex, numerical values). These operators have been overloaded to allow comparison of dates, as well as string representations of valid dates:
- Less than (
<
) - Less than or equal to (
<=
) - Greater than (
>
) - Greater than or equal to (
<=
) - Equal (
==
) - Not equal (
!=
)
This allows the usage of dates in expressions that can be evaluated to true
or false
. For example:
if("2017-03-11T10:15:00:123Z" < now(), "past", "not past")
Standard "element" operator ([]
) was overloaded to support data extraction out of JSON arrays and other collections by index.
jsonArray[1] //extracts the first element of the given jsonArray
Note: Also achievable using the function
get(jsonArray, 1)
.
If you are using Maven, add jep-data-extension as a dependency to your pom.xml file.
<dependency>
<groupId>net.obvj</groupId>
<artifactId>jep-data-extension</artifactId>
<version>1.0.7</version>
</dependency>
If you use other dependency managers (such as Gradle, Grape, Ivy, etc.) click here.
-
Add
jep-data-extensions
to your class path -
Put your source variables in a map:
Map<String, Object> myVariables = new HashMap<>(); myVariables.put("myText", "foo");
-
Use the
JEPContextFactory
class to create an extended JEP object with all available extensions:JEP jep = JEPContextFactory.newContext(myVariables);
Note: Alternatively, you may use the
JEPContextFactory.newContext()
to receive a new context with no initial variables. You may add them later, callingjep.addVariable(String, Object)
. -
Parse your expression:
Node node = jep.parseExpresion("replace(myText, \"oo\", \"ee\")");
-
Evaluate the expression with JEP's
evaluate
method:String result = (String) jep.evaluate(node); //result = "fee"
-
Alternatively, you can use the assignment operator inside an expression. The new variable will be available in JEP context for reuse and can be retrieved using the
getVarValue
method:Node node = jep.parseExpression("myText = replace(\"fear\", \"f\", \"d\")")); jep.evaluate(node); String result = (String) jep.getVarValue("myText"); //result = "dear"
The ExpressionEvaluatorFacade
is a convenient object to quickly parse a single expression. A single call to the evaluate
method will create a new evaluation context and return the expression result directly. It accepts a map with initial variables for use in the operation.
-
Put your source variables in a map:
Map<String, Object> myVariables = new HashMap<>(); myVariables.put("date1", "2018-12-20T09:10:00.123456789Z");
-
Evaluate your expression:
String expression = "if(date1 < now(), \"overdue\", \"not overdue\")"; String result = (String) ExpressionEvaluatorFacade.evaluate(expression, myVariables); //result = "overdue"
-
Run
jep-data-extension
JAR file from a terminal:$ java -jar jep-data-extension-1.0.2.jar
-
Consume the RESTful API with the
httpGet
function:JEP > dateTime = httpGet("http://date.jsontest.com/") { "time": "08:31:19 PM", "date": "05-12-2012" }
-
Filter the JSON using a JsonPath expression that extracts the date field:
JEP > date = jsonpath(dateTime, "$.date") 05-12-2012
-
Check the type of the generated
date
variable:JEP > class(date) java.lang.String
-
Convert the string to Date:
JEP > date = str2date(date, "dd-MM-yyyy") Wed Dec 05 00:00:00 BRST 2012
-
Extract the week number from the converted date:
JEP > isoWeekNumber(date) 49