Question

I’m trying to write a function in clojure that prints out xml using clojure.xml/emit.

(ns test.xml.emit
  (:use clojure.core)
  (:require [clojure.xml :as xml]))

(defn testemit []
  (xml/emit {:tag :web-app
             :attrs {:xmlns:xsi "http://www.w3.org/2001/XMLSchema-instance"
                     :xmlns "http://java.sun.com/xml/ns/javaee"
                     :xmlns:web "http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"
                     :xsi:schemaLocation "http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"
                     :id "Foo"
                     :version "1.0"},
             :content [{:display-name "FooBar+"}
                       {:listener
                        {:listener-class "com.example.server.Main"}}
                       {:filter
                        {:filter-name "guiceFilter"}
                        {:filter-class "com.google.inject.servlet.GuiceFilter"}}
                       {:filter-mappings
                        {:filter-name "guiceFilter"}
                        {:url-pattern "/*"}}]}))

I know what the exception means, but I’m not sure howit relates to my code. Could someone please point me in the right direction?
The full stack trace is available at https://gist.github.com/1838248

Thank you for your time and consideration

Answer 1

The error for this in Clojure 1.3 is a bit more helpful: “Map literal must contain an even number of forms”.

The problem is in the last two entries of the :content vector: they are literal maps containing three forms. Maps consist of key-value pairs, so must contain an even number.

Further, the stuff in :content doesn’t look like valid data to pass to emit. Each node should have :tag, :attrs, and :content attributes, or be a string.