implement ReadRawTask. Fixes #44. Fixes #45.

CHANGELOG.md

@@ -24,6 +24,13 @@ vendored versions of ExifTool match the version they vendor.
 
 ## Version history
 
+### v8.2.0
+
+- ✨ Implemented `ExifTool.readRaw`. If you decide to use this method, please
+  take care to read the method's documentation. Addresses both
+  [#44](https://github.com/mceachen/exiftool-vendored.js/issues/44) and
+  [#45](https://github.com/mceachen/exiftool-vendored.js/issues/45).
+
 ### v8.1.0
 
 - ✨ Added support for EXIF dates that include both the UTC offset as well as the

package.json

@@ -69,7 +69,7 @@
     "@types/globule": "^1.1.3",
     "@types/luxon": "^1.11.1",
     "@types/mocha": "^5.2.6",
-    "@types/node": "^11.9.4",
+    "@types/node": "^11.9.5",
     "@types/pify": "^3.0.2",
     "@types/progress": "^2.0.3",
     "@types/rimraf": "^2.0.2",
@@ -82,7 +82,7 @@
     "decompress-zip": "^0.3.1",
     "fs-extra": "^7.0.1",
     "globule": "^1.2.1",
-    "mocha": "^6.0.0",
+    "mocha": "^6.0.2",
     "npm-run-all": "^4.1.5",
     "nyc": "^13.3.0",
     "pify": "^4.0.1",
@@ -94,7 +94,7 @@
     "tar-fs": "^2.0.0",
     "tmp": "^0.0.33",
     "typedoc": "^0.14.2",
-    "typescript": "^3.3.3",
+    "typescript": "^3.3.3333",
     "xmldom": "^0.1.27",
     "xpath": "^0.0.27"
   },

src/ExifTool.spec.ts

@@ -63,6 +63,14 @@ describe("ExifTool", function() {
     )
   })
 
+  it("returns raw tag values", async () => {
+    return expect(et.readRaw(img, ["-Make", "-Model"])).to.eventually.eql({
+      Make: "Apple",
+      Model: "iPhone 7 Plus",
+      SourceFile: img
+    }) // and nothing else
+  })
+
   it("returns expected results for a given file with non-english filename", async function() {
     this.slow(500)
     return expect(

src/ExifTool.ts

@@ -13,6 +13,7 @@ import { RewriteAllTagsTask } from "./RewriteAllTagsTask"
 import { Tags } from "./Tags"
 import { VersionTask } from "./VersionTask"
 import { WriteTask } from "./WriteTask"
+import { ReadRawTask } from "./ReadRawTask"
 
 export { Tags } from "./Tags"
 export { ExifDate } from "./ExifDate"
@@ -231,8 +232,9 @@ export class ExifTool {
    *
    * @param {string} file the file to extract metadata tags from
    * @param {string[]} [args] any additional ExifTool arguments, like "-fast" or
-   * "-fast2". Note that the default is "-fast", so if you want ExifTool to read
-   * the entire file for metadata, you should pass an empty array as the second
+   * "-fast2". **Most other arguments will require you to use `readRaw`.**
+   * Note that the default is "-fast", so if you want ExifTool to read the
+   * entire file for metadata, you should pass an empty array as the second
    * parameter. See https://sno.phy.queensu.ca/~phil/exiftool/#performance for
    * more information about `-fast` and `-fast2`.
    * @returns {Promise<Tags>} A resolved Tags promise. If there are errors
@@ -245,6 +247,32 @@ export class ExifTool {
     )
   }
 
+  /**
+   * Read the tags from `file`, without any post-processing of ExifTool values.
+   *
+   * **You probably don't want this method. You want `read`. READ THE REST OF THIS CAREFULLY.** 
+   *
+   * If you want to extract specific tag values from a file, you may want to use
+   * this, but all data validation and error recovery heuristics provided by
+   * `read` will be skipped.
+   *
+   * Note that performance will be very similar to `read`, and will actually be
+   * worse if you don't include `-fast` or `-fast2` (as the most expensive bit
+   * is the perl interpreter and scanning the file on disk).
+   *
+   * @param args **all ExifTool arguments**, except for the file path. If
+   * `-charset` or `filename=utf8` are missing, and you have non-ascii tag
+   * values, you're going to have a bad day. The resolved pathname will be
+   * appended to the args array for you, and if `-json` is missing from `args`,
+   * that will be prepended, as it's a prerequisite to parsing the result.
+   *
+   * @return Note that the values **might** match `Tags`, but they might not.
+   * You're off the reservation here.
+   */
+  readRaw(file: string, args: string[]): Promise<Tags> {
+    return this.enqueueTask(() => ReadRawTask.for(file, args))
+  }
+
   /**
    * Write the given `tags` to `file`.
    *

src/ReadRawTask.ts

@@ -0,0 +1,32 @@
+import { logger } from "batch-cluster"
+import * as _path from "path"
+
+import { ExifToolTask } from "./ExifToolTask"
+import { Tags } from "./Tags"
+
+export class ReadRawTask extends ExifToolTask<Tags> {
+  static for(filename: string, exiftoolArgs: string[] = []): ReadRawTask {
+    const args = [...exiftoolArgs]
+    if (!args.includes("-json")) args.unshift("-json")
+    const sourceFile = _path.resolve(filename)
+    args.push(sourceFile)
+    return new ReadRawTask(sourceFile, args)
+  }
+
+  private constructor(readonly sourceFile: string, readonly args: string[]) {
+    super(args)
+  }
+
+  toString(): string {
+    return "ReadRawTask" + this.sourceFile + ")"
+  }
+
+  protected parse(data: string, err?: Error): Tags {
+    try {
+      return JSON.parse(data)[0]
+    } catch (jsonError) {
+      logger().error("ExifTool.ReadRawTask(): Invalid JSON", { data })
+      throw err || jsonError
+    }
+  }
+}

yarn.lock

@@ -166,11 +166,16 @@
   resolved "https://registry.yarnpkg.com/@types/mocha/-/mocha-5.2.6.tgz#b8622d50557dd155e9f2f634b7d68fd38de5e94b"
   integrity sha512-1axi39YdtBI7z957vdqXI4Ac25e7YihYQtJa+Clnxg1zTJEaIRbndt71O3sP4GAMgiAm0pY26/b9BrY4MR/PMw==
 
-"@types/node@*", "@types/node@^11.9.4":
+"@types/node@*":
   version "11.9.4"
   resolved "https://registry.yarnpkg.com/@types/node/-/node-11.9.4.tgz#ceb0048a546db453f6248f2d1d95e937a6f00a14"
   integrity sha512-Zl8dGvAcEmadgs1tmSPcvwzO1YRsz38bVJQvH1RvRqSR9/5n61Q1ktcDL0ht3FXWR+ZpVmXVwN1LuH4Ax23NsA==
 
+"@types/node@^11.9.5":
+  version "11.9.5"
+  resolved "https://registry.yarnpkg.com/@types/node/-/node-11.9.5.tgz#011eece9d3f839a806b63973e228f85967b79ed3"
+  integrity sha512-vVjM0SVzgaOUpflq4GYBvCpozes8OgIIS5gVXVka+OfK3hvnkC1i93U8WiY2OtNE4XUWyyy/86Kf6e0IHTQw1Q==
+
 "@types/pify@^3.0.2":
   version "3.0.2"
   resolved "https://registry.yarnpkg.com/@types/pify/-/pify-3.0.2.tgz#1bc75dac43e31dba981c37e0a08edddc1b49cd39"
@@ -1763,10 +1768,10 @@ mkpath@^0.1.0:
   resolved "https://registry.yarnpkg.com/mkpath/-/mkpath-0.1.0.tgz#7554a6f8d871834cc97b5462b122c4c124d6de91"
   integrity sha1-dVSm+Nhxg0zJe1RisSLEwSTW3pE=
 
-mocha@^6.0.0:
-  version "6.0.0"
-  resolved "https://registry.yarnpkg.com/mocha/-/mocha-6.0.0.tgz#b558da6245a09581aa4a1c6aee9e0fa6ad0e1767"
-  integrity sha512-A7g9k3yr8oJaXn2IItFnfgjyxFc/LTe6Wwv7FczP+e8G74o9xYNSbMYmCf1ouldRojLrFcOb+z75P6Ak0GX6ug==
+mocha@^6.0.2:
+  version "6.0.2"
+  resolved "https://registry.yarnpkg.com/mocha/-/mocha-6.0.2.tgz#cdc1a6fdf66472c079b5605bac59d29807702d2c"
+  integrity sha512-RtTJsmmToGyeTznSOMoM6TPEk1A84FQaHIciKrRqARZx+B5ccJ5tXlmJzEKGBxZdqk9UjpRsesZTUkZmR5YnuQ==
   dependencies:
     ansi-colors "3.2.3"
     browser-stdout "1.3.1"
@@ -2793,10 +2798,10 @@ typescript@3.2.x:
   resolved "https://registry.yarnpkg.com/typescript/-/typescript-3.2.4.tgz#c585cb952912263d915b462726ce244ba510ef3d"
   integrity sha512-0RNDbSdEokBeEAkgNbxJ+BLwSManFy9TeXz8uW+48j/xhEXv1ePME60olyzw2XzUqUBNAYFeJadIqAgNqIACwg==
 
-typescript@^3.3.3:
-  version "3.3.3"
-  resolved "https://registry.yarnpkg.com/typescript/-/typescript-3.3.3.tgz#f1657fc7daa27e1a8930758ace9ae8da31403221"
-  integrity sha512-Y21Xqe54TBVp+VDSNbuDYdGw0BpoR/Q6wo/+35M8PAU0vipahnyduJWirxxdxjsAkS7hue53x2zp8gz7F05u0A==
+typescript@^3.3.3333:
+  version "3.3.3333"
+  resolved "https://registry.yarnpkg.com/typescript/-/typescript-3.3.3333.tgz#171b2c5af66c59e9431199117a3bcadc66fdcfd6"
+  integrity sha512-JjSKsAfuHBE/fB2oZ8NxtRTk5iGcg6hkYXMnZ3Wc+b2RSqejEqTaem11mHASMnFilHrax3sLK0GDzcJrekZYLw==
 
 tz-lookup@^6.1.8:
   version "6.1.8"