sanitizePostsMeta(model) {
        let postsMetaFromFile = _.find(this.requiredFromFile.posts_meta, {post_id: model.id}) || _.pick(model, metaAttrs);
        let postsMetaData = Object.assign({}, _.mapValues(postsMetaSchema, (value) => {
            return Reflect.has(value, 'defaultTo') ? value.defaultTo : null;
        }), postsMetaFromFile);
        model.posts_meta = postsMetaData;
        _.each(metaAttrs, (attr) => {
            delete model[attr];
        });
    }
Sanitizes post metadata, picking data from sepearate table(for >= v3) or post itself(for < v3)