index.js

var nunjucks = require('nunjucks');
var path = require('path');
var debug = require('debug')('koa-nunjucks-promise');

module.exports = function (root, opts) {
  var basePath = path.dirname(module.parent.filename);

  if (typeof root === 'object') {
    opts = root;
    root = opts.root || basePath;
  } else if (!root) {
    root = basePath;
  }

  root = path.resolve(basePath, root);

  opts = opts || {};

  var env = nunjucks.configure(root, opts);

  var ext = opts.ext || 'html';

  var filters = opts.filters || {};
  Object.keys(filters).forEach(f => {
    env.addFilter.apply(env, [f].concat(filters[f]));
  });

  var globals = opts.globals || {};
  Object.keys(globals).forEach(g => {
    env.addGlobal(g, globals[g]);
  });

  return function (ctx, next) {
    if (ctx.render) return next();
    ctx.render = function (view, locals) {
      locals = locals || {};
      var state = ctx.state || {};
      var context = Object.assign({}, state, locals);
      debug('render %s with %j', view, context);
      return new Promise(function (resolve, reject) {
        var name = view + '.' + ext;
        env.render(name, context, function (err, res) {
          if (err) return reject(err);
          ctx.body = res;
          ctx.type = 'text/html';
          resolve();
        });
      });
    };
    return next();
  }
};