Need Regular Expression in scala

Question

This is my response

   scala > val a= """{"string":"{\"data\":{\"id\":\"2c91809f4ef7678b014ef86ee28511c2\",\"unitName\":\"gatlir1\",\"owner\":\"gatlir1\",\"description\":\"gatlir1\",\"nofChairs\":0,\"nofBeds\":0,\"nofApptStartWithInHour\":0,\"nofApptDischargeWithInHour\":0,\"modifiedDateTime\":\"Aug 4, 2015 4:18:13 AM\"},\"status\":\"SUCCESS\",\"message\":\"unit_save\"}"}"""

i need to fetch id value from that response in scala. i have stored response in one variable. and i have written regular expression for that and stored in another variable.

Here is the problem , i am getting error. RegEx:

     scala> val b= """{\"id\":\"(\w+)\""""

while inserting regex into "b" , i didn't get any error, but while comparing i am getting error

if i write expression like this

          scala> a.matches(b) 

error:

  java.util.regex.PatternSyntaxException: Illegal repetition
   {\"id\":\"(\w+)\"
   at java.util.regex.Pattern.error(Pattern.java:1955)
   at java.util.regex.Pattern.closure(Pattern.java:3157)
   at java.util.regex.Pattern.sequence(Pattern.java:2134)
   at java.util.regex.Pattern.expr(Pattern.java:1996)
   at java.util.regex.Pattern.compile(Pattern.java:1696)
   at java.util.regex.Pattern.<init>(Pattern.java:1351)
   at java.util.regex.Pattern.compile(Pattern.java:1028)
   at java.util.regex.Pattern.matches(Pattern.java:1133)
   at java.lang.String.matches(String.java:2109)

could any one help me in this..

Answer 1

Why are you using regular expressions here? Just read the JSON. JSON is not a regular language, and can not be easily described with regex.

Here's one of many library's that will parse JSON for Scala https://github.com/json4s/json4s

It'll also make accessing any of the other objects inside much easier.

Answer 2

您应该转义{ ：

val b= """\{\"id\":\"(\w+)\""""

Answer 3

Here is the fixed code:

val a= """{"string":"{"data":{"id":"2c91809f4ef7678b014ef86ee28511c2","unitName":"gatlir1","owner":"gatlir1","description":"gatlir1","nofChairs":0,"nofBeds":0,"nofApptStartWithInHour":0,"nofApptDischargeWithInHour":0,"modifiedDateTime":"Aug 4, 2015 4:18:13 AM"},"status":"SUCCESS","message":"unit_save"}"}"""
val b= """\{"id":"(\w+)""".r
val allMatches = b.findAllMatchIn(a)
allMatches.foreach { m =>
     println(m.group(1))
}

It prints: 2c91809f4ef7678b014ef86ee28511c2 .

See demo

Note you do not have to escape double quotes inside """ quoted strings (see this SO answer ).