config

const configuration = {
  db: {
    name: 's3-db',
    environment: 'dev',
    pageSize : 10,
    allowDrop: false
  },
  provider: {
    name: 's3',
    region: 'us-east-1'
  },
  collections: {
    testdb: {
      collideOnMissmatch: true,
      onlyUpdateOnMD5Change: false,
      id: {
        propertyName: '_id',
      },
      validator: document => apps_validator(document) ? Promise.resolve(document) : Promise.reject("validator fail"),
      collisionValidator: (thisMetadata, thatMetadata) => {
        const isValid = !thatMetadata || !thatMetadata._rev || thatMetadata._rev == thisMetadata._rev;
        console.log('rev: target rev: %s, this rev: %s', thatMetadata._rev, thisMetadata._rev)
        if (isValid)
        return isValid;
      },
      metadataUpdate: metadata => {
        metadata._rev = (metadata._rev) ? (parseInt(metadata._rev) + 1).toString() : "1";
        //console.log('setting metadata', metadata)
        return metadata;
      }
    }
  },
  serializer: {
    serialize: data => {
      //console.log('serializing')
      data._rev = data._rev ? (parseInt(data._rev) + 1).toString() : "1";
      //console.log('new data:', data)
      return JSON.stringify(data)
    },
    deserialize: data => JSON.parse(data)
  }
};

gistfile1.txt

const isCollided = (document, argMetatada={}) => {

    if(document.getId || document[idPropertyName]){

      const id       = document.getId ? document.getId() : document[idPropertyName];
      const metadata = document.getId ? Utils.getMetaData(document) : argMetatada;

      return collectionProvider.getDocumentHead(fqn,id)
        .then( head => {

          const targetMetaData = document.getId ? provider.document.buildDocumentMetaData(head) : head.Metadata;
          let   hasChanged     = false;
          let   isValid        = false

          /*
           * Extension point that allows additional checking on the metadata of the document
           *  and the corresponding documentHeader.
           **/
          if(collisionValidator){
            isValid = collisionValidator(metadata,targetMetaData,document);
            if (isValid) return Promise.resolve(document);
            else return Promise.reject('collisionValidator, failed to validate.');
          }

          /*
           * The targetMetaData comes from a headCheck on the object being
           *  overwritten. So if the MD5 on the __meta of the current record
           *  matches the target MD5, the underlying object is likely not
           *  modified.
           *
           * Md5 does not always get returned.
           */
          if(!hasChanged && targetMetaData.md5 && targetMetaData.md5 !== metadata.md5){
            hasChanged = true;
          }

          if(!hasChanged && targetMetaData.eTag !== metadata.eTag){
            hasChanged = true;
          }

          if(hasChanged){
            return Promise.reject('Collision, the document has been modified.');
          }

          return Promise.resolve(document);
        })
        .catch( error => 'NotFound' === error.code ? Promise.resolve(document) : handleError(error) )
    }
    return Promise.resolve(document);
  }