gulp-set-property-from-path

A gulp plugin for setting one or more arbitrary values in a file based on its path.

Setup and usage

Install gulp-set-property-from-path using npm:

npm i gulp-set-property-from-path

In your gulpfile.js:

var gulp = require('gulp'),
    gulpGrayMatter = require('gulp-gray-matter'),
    gulpSetPropertyFromPath = require('gulp-set-property-from-path');

gulp.task('default', function() {
  return gulp.src('./src/**.*')
    .pipe(gulpGrayMatter({ property: "data" }))
    .pipe(gulpSetPropertyFromPath({
        path: /(\d\d\d\d)-(\d\d)-(\d\d)/,
        set: {
            "data.year": "$1",
            "data.month": "$2",
            "data.day": "$3",
            "data.date": "$1-$2-$3"
        }
    }))
    .pipe(gulp.dest('./dest'));
});

A common workflow using this tool is to set dates based on a path (such as Jekyll-style blog postings) or inject a prefix in front of filenames.

Options

path

RegExp

Default: /(\d{4}).(\d{2}).(\d{2})/

The regular expression to scan the file.path attribute. If this does not match, then no changes are made to the object.

set

object

Default: {}

An object that contains property/value pairs that should be set inside the object. There can be zero or more of these. The property name is the property of the file that needs to be set such as data.date. It can be a nested property name like data.inner.date.

The value is a Perl-style replacement of a dollar ($) followed by a single digit number such as $1. This matches to the group of the path regular expression.

A special case is $0 which puts the value of the previous property in its place. The below example prefixes all of the title properties with "Chapter X: " where X is the number in the filename. If there is a $0 and the property does not exist, then that key in the set parameter is skipped but other values may be set.

var gulp = require('gulp'),
    gulpGrayMatter = require('gulp-gray-matter'),
    gulpSetPropertyFromPath = require('gulp-set-property-from-path');

gulp.task('default', function() {
  return gulp.src('./src/**.*')
    .pipe(gulpGrayMatter({ property: "data" }))
    .pipe(gulpSetPropertyFromPath({
        path: /chapter-(\d\d)/,
        set: {
            "data.title": "Chapter $1: $0"
        }
    }))
    .pipe(gulp.dest('./dest'));
});