Passing gulp-front-matter value to gulp-wrap

Question

I'm hoping to do something like this:

gulp.src('src/*.html')
  .pipe(fm ({
    property: 'fm'
  }))
  .pipe(wrap({
    src: fm['template']
  }))

where template is a value in the front-matter. I can create a separate function where I pass the value using gulp-tap but I was hoping to keep it "simple". I don't think gulp-wrap supports accessing front-matter vars.

Answer 1

This seems to be one solution but it starts to fail as I add more complexity, for instance with gulp-swig.

The source file contains:

---
template: full
---

Text content is here.

and the script:

var frontMatter   = require('gulp-front-matter'),
    gulp          = require('gulp'),
    tap           = require('gulp-tap'),
    wrap          = require('gulp-wrap')

gulp.task('default', function() {
  gulp.src('src/*.html')
    .pipe(frontMatter())
    .pipe(tap(function(file) {
      gulp.src(file.path)
        .pipe(frontMatter ({
          remove: true
        }))
        .pipe(wrap({
          src: file.frontMatter['template'] + '.tpl' // ==> full.tpl
        }))
        .pipe(gulp.dest('build/'))
    }))
});

Answer 2

You need to pass a function as the first argument of gulp-wrap.

The document of gulp-wrap says

When a Function then the function will be called and should return the template content. This function get the data object as first parameter.

Something like the following should work.

var gulp = require('gulp')
var fm = require('gulp-front-matter')
var wrap = require('gulp-wrap')

var fs = require('fs')

gulp.src('src/*.html')
  .pipe(fm({property: 'fm'}))
  .pipe(wrap(function (data) {
    return fs.readFileSync('path/to/layout_dir/' + data.file.fm.template + '.tpl').toString()
  }))
  .pipe(gulp.dest('build/'))

See also: Gulp Front Matter +Markdown through Nunjucks