Notes // metalsmith-collections: Solving the Duplication Bug

Simple solution to clear the collections between builds for the metalsmith-collections plugin.

The metalsmith-collections plugin is a great simple way to manage the projects and blog posts on this website. It has one flaw: when rebuilding a website it does not remove the old elements in the collection(s); this creates duplicate information for each file in the collection after every re-build.

This is a simple bug and there is already a pull request that will hopefully solve the issue. Until that time, I came up with a temporary solution to remove the old elements from the collection.

The Code

Create a file named clear_collections.js.

// clear_collections.js
module.exports = (collectionNames) => {
    return function (files, metalsmith, done) {
        "use strict";
        let meta = metalsmith.metadata();

        for (let collection of collectionNames) {
            if (collection in meta) {
                meta[collection] = [];

In your build.js file, import the clear_collections plugin and add it to the .use() chain before you run the metalsmith-collections plugin. Add the collection names as an option passed to the clear_collections plugin.

// build.js
const clear_collections = require("./clear_collections");

// the .use() chain
.use(clear_collections(["collection1", "etc..."]))
        collection1:"...collection1 options",
        etc: "etc options..."

Restart your build process.

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