From db88b28779cacc303d2dfe3190ab25c7bd741b50 Mon Sep 17 00:00:00 2001
From: maxlath <k@maxlath.eu>
Date: Mon, 22 Aug 2016 21:49:30 +0200
Subject: [PATCH] documenting mapper

---
 README.md | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/README.md b/README.md
index 4f94025..6ef3fae 100644
--- a/README.md
+++ b/README.md
@@ -46,6 +46,25 @@ To keep a sync process going, run
 couch2elastic4sync
 ```
 
+### Format and filter documents
+
+A `mapper` function can be passed from the config to format documents before being put to ElasticSearch:
+```ini
+database=http://localhost:5984/idx-edm-v5
+elasticsearch=http://elastic-1.com:9200/idx-edm-v5/listing
+mapper=path/to/my-mapper.js
+```
+
+Where my-mapper.js could be something like
+```
+module.exports = function (doc) {
+  // apply formatting here
+  return doc
+}
+```
+
+If the function returns empty, the document is filtered-out
+
 ## License
 
 MIT