This library provides functions for parsing and manipulating HL7 version 2.x Messages.

To use these functions, first require it in your project.

(ns com.example.project
  (:require
    [com.nervestaple.hl7-parser.parser :as parser]
    [com.nervestaple.hl7-parser.message :as message]))

The "parser" namespace contains functions for parsing and emitting HL7 version 2.x messages. The "message" namespace contains functions for pulling specific information out of a parsed message as well as manipulating messages.

In addition, the "dump" namespace has some functions for displaying a parsed message in a human-readable format. The "util" namespace has methods that may come in handy while your developing your HL7 solution. The "test" namespace contains functions to make testing easier, including a test HL7 message.

In this example we have the text of an incoming HL7 version 2.x message in a var called "text-message" parsing it is as easy as...

(def parsed-message (parser/parse message))

The parsed message is a hash-map that contains all of the information contained in the message. It's not a lot of fun to look at.

{:delimiters {:field 124, :component 94, :subcomponent 38,
              :repeating 126, :escape 92}, 
 :segments [{:id "MSH", :fields [{:content "^~\\&"} 
            {:content ["AcmeHIS"]} {:content ["StJohn"]}
            {:content ["CATH"]} {:content["StJohn"]}...]}

The "message" namespace provides functions that make it easy to get the information you need out of this structure.

user> (message/get-field parsed-message "MSH" 10)
({:content ["1291058687937"]})

You probably just want the actual value and not the field from the parsed data structure.

user> (message/get-field-first-value parsed-message "MSH" 10)
"1291058687937"

Take a look at the source code, there are functions for retrieving whole segments, extracting text and changing the value of fields.

Generating acknowledgment messages is easy, we provide a function in the message namespace just for this purpose. Pass in the required options, your acknowledgment status and the parsed message that you are acknowledging.

(message/ack-message {:sending-app "MYAPP"
                      :sending-facility "TEST LAB"
                      :production-mode "P"
                      :version "2.3"
                      :text-message "Successfully received"}
                      "AA" parsed-message)

This function will return a parsed message containing the acknowledgment.

Creating new HL7 messages is easy. You'll need a set of delimiters, you can create these manually or retrieve them from a message you have already parsed.

user> (:delimiters parsed-message)
{:field 124, :component 94, :subcomponent 38, :repeating 126,
:escape 92}

Delimiters are stored by their character code in a hashmap. You can use the "delimiters-struct" in the "parser" namespace if you need to setup your own.

user> (struct-map parser/delimiters-struct :field 124
:component 94 :subcomponent 38 repeating 126 escape 92)

We have functions for building up messages in the "message" namespace.

(create-message my-delimiters
  (create-segment "MSH"
      (create-field (parser/pr-delimiters my-delimiters))
      (create-field ["MYAPP"])
      (create-field ["TEST LAB"])
      (create-field ["19202830920"])))

That's not a real message or a complete MSH segment but you get the idea.

Emitting a message is also pretty straightforward.

user> (parser/pr-message parsed-message)
MSH|^~\&|AcmeHIS|StJohn|CATH|StJohn|20061019172719|...

You can also emit pieces of a message, like the delimiters or a segment or field. The field and segment methods require that you also pass in the delimiters for the message.

user> (parser/pr-segment my-delimiters pid-segment)
"PID|||20301||Durden^Tyler^^^Mr.||19700312|M|||..."

I am actively using this library in several projects and will continue to work on this code. If you have any suggestions or patches, please fork this project and send me a pull request. :)