s3-object.js

"use strict";

const { pick, pickBy } = require("lodash");

class S3Object {
  constructor(bucket, key, content, metadata) {
    this.bucket = bucket;
    this.key = key;
    this.content = content;
    this.metadata = pick(metadata, [
      "cache-control",
      "content-disposition",
      "content-encoding",
      "content-language",
      "content-type",
      "expires",
      "website-redirect-location",

      // instrinsic metadata determined when retrieving objects
      "last-modified",
      "etag",
      "content-length"
    ]);
    if (!this.metadata["content-type"]) {
      this.metadata["content-type"] = "binary/octet-stream";
    }
    Object.assign(
      this.metadata,
      pickBy(metadata, (v, k) => k.startsWith("x-amz-meta-"))
    );
  }

  get size() {
    return Number(this.metadata["content-length"]);
  }

  get lastModifiedDate() {
    return new Date(this.metadata["last-modified"]);
  }
}
module.exports = S3Object;