Merge branch '4-ensure-index-exists' into 'master'

Generate an unique index for place.uri

Closes #4

See merge request !8

src/index.ts

@@ -3,6 +3,7 @@ import {Core} from 'geolinker-common';
 import Neo4jStreamWriter from './neo4j-stream-writer';
 import {v1 as neo4j} from 'neo4j-driver';
 import KafkaAvro = require('kafka-avro');
+import Session from 'neo4j-driver/types/v1/session';
 
 /**
  * To trigger this you need to set the KAFKA_AVRO_LOG_LEVEL
@@ -47,6 +48,13 @@ kafka.init().then(() => {
         core.getNconf().get('neo4j:config:user'),
         core.getNconf().get('neo4j:config:password'),
       ));
+
+    /**
+     * Add index and constraint to DB. If the index exists the query is ignored
+     * todo: not 100% sure if this is the right place to define the indexes
+     */
+    await driver.session().run('CREATE CONSTRAINT ON (p:Place) ASSERT p.uri IS UNIQUE');
+
     /**
      * pipe the stream from kafka fo neo4j
      */