major changes:

-- fixed issue in case of target type different from source type -- changed default path in sample-config to output/data.json

Author: Gaurang Pansare

.gitignore

@@ -1,5 +1,6 @@
 # Custom
 config.js
+output
 
 # Logs
 logs

README.md

@@ -7,7 +7,7 @@ Since Node.js is single-threaded, `producer` and `consumer` cannot simultaneousl
 ### Usage:
 1. Clone the repo.
 2. Run `npm install` in the directory.
-3. Add `config.js` using [`config-sample.js`][1]
+3. Add `config.js` using [`config-sample.js`][1]. Exercise caution while setting source and target elastic hosts.
 4. (Optional) Set appropriate values in [`options.js`][2]
 5. Run the script
  ```

config-sample.js

@@ -15,7 +15,7 @@ module.exports = Object.freeze({
 "type": "_doc",
 
  //if options.consume.byFile is not set, this will be ignored
-"filePath": "data.json",
+"filePath": "output/data.json",
 
  //if options.consume.byElastic is not set, this will be ignored
 "host": "localhost:9200",

elastic.js

@@ -15,6 +15,14 @@ class Elastic{
  }
  this.batches = 0;
  this._scroll_id = null;
+
+ this._targetConfigCheckIf = property => flag => {
+ switch(flag){
+ case 'given': return !!config.target[property];
+ case 'same': return config.target[property] === config.source[property];
+ default: throw new Error(`Error with mapping: ${property}`);
+ }
+ }
  }
 
  async init(){
@@ -78,7 +86,6 @@ class Elastic{
  return accumulator.concat([{index}, hit._source])
  }, []);
 
- //console.log(body);
  console.log('Elastic Doc Count', this.target.doc_count.elastic);
  return this.targetClient.bulk({body});
  }
@@ -110,21 +117,40 @@ class Elastic{
  }
 
  async _transferMapping(source, target){
- let mapping = await source.indices.getMapping({
+ let sourceMapping = await source.indices.getMapping({
  index: config.source.index,
  type: config.source.type
  })
- console.log("Mapping: ", JSON.stringify(mapping));
+
+ let mapping = this._buildMappingFrom(sourceMapping);
 
  if(!await target.indices.exists({index: config.target.index}))
  await target.indices.create({index: config.target.index});
 
  return await target.indices.putMapping({
  index: config.target.index,
  type: config.target.type,
- body: mapping[config.source.index].mappings
+ body: mapping
  });
  }
+
+ //sourceMapping:
+ //{<index>: {"mappings": {<type>: {<the mapping>}}}}
+ //To return:
+ //{<type>: <mapping>}
+ _buildMappingFrom(sourceMapping){
+ let base = {};
+ let type = Object.assign({}, sourceMapping[config.source.index].mappings[config.source.type]);
+
+ //if target 'type' given in config is different from the type in source elastic, change it
+ if(this._targetConfigCheckIf('type')('given') && !this._targetConfigCheckIf('type')('same'))
+ base[config.target.type] = type;
+ else
+ base[config.source.type] = type;
+
+ //base = {<type>: <mapping>}
+ return base;
+ }
 }
 
 module.exports = {Elastic}