index.js

/*******************************************************************
 *
 *  This module was heavily inspired by nunjucksify.
 *  (https://www.npmjs.com/package/nunjucksify)
 *
 *  Full credit to the original authors.
 *
 ******************************************************************/

var nunjucks = require('nunjucks');
var slash = require('slash');
var path = require('path');
var loaderUtils = require('loader-utils');
var env;
var hasRun = false;
var pathToConfigure;
var jinjaCompatStr;
var root;

module.exports = function (source) {
    if (this.target !== 'web') {
        throw new Error('[nunjucks-loader] non-web targets are not supported');
    }

    this.cacheable();

    if (!hasRun){
        var query = loaderUtils.parseQuery(this.query);

        if (query){

            env = new nunjucks.Environment([], query.opts || {});

            if (query.config){
                pathToConfigure = query.config;
                try {
                    var configure = require(query.config);
                    configure(env);
                }
                catch (e) {
                    if (e.code === 'MODULE_NOT_FOUND') {
                        if (!query.quiet) {
                            var message = 'Cannot configure nunjucks environment before precompile\n' +
                                    '\t' + e.message + '\n' +
                                    'Async filters and custom extensions are unsupported when the nunjucks\n' +
                                    'environment configuration depends on webpack loaders or custom module\n' +
                                    'resolve rules. If you are not using async filters or custom extensions\n' +
                                    'with nunjucks, you can safely ignore this warning.'
                                ;
                            this.emitWarning(message);
                        }
                    }
                    else {
                        this.emitError(e.message);
                    }
                }
            }

            // Specify the template search path, so we know from what directory
            // it should be relative to.
            if (query.root) {
                root = query.root;
            }

            // Enable experimental Jinja compatibility to be enabled
            if(query.jinjaCompat){
                jinjaCompatStr = 'nunjucks.installJinjaCompat();\n';
            }
        }
        else {
            env = new nunjucks.Environment([]);
        }
        hasRun = true;
    }

    var name = slash(path.relative(root || this.options.context, this.resourcePath));

    var nunjucksCompiledStr = nunjucks.precompileString(source, {
            env: env,
            name: name
        });

    nunjucksCompiledStr = nunjucksCompiledStr.replace(/window\.nunjucksPrecompiled/g, 'nunjucks.nunjucksPrecompiled');

    // ==============================================================================
    // replace 'require' filter with a webpack require expression (to resolve assets)
    // ==============================================================================
    var filterReg = /env\.getFilter\(\"require\"\)\.call\(context, \"(.*?)\"/g;
    nunjucksCompiledStr = nunjucksCompiledStr.replace(filterReg, 'require("$1"');

    // ================================================================
    // Begin to write the compiled template output to return to webpack
    // ================================================================
    var compiledTemplate = '';
    compiledTemplate += 'var nunjucks = require("nunjucks/browser/nunjucks-slim");\n';
    if (jinjaCompatStr) {
        compiledTemplate += jinjaCompatStr + '\n';
    }
    compiledTemplate += 'var env;\n';
    compiledTemplate += 'if (!nunjucks.currentEnv){\n';
    compiledTemplate += '\tenv = nunjucks.currentEnv = new nunjucks.Environment([], { autoescape: true });\n';
    compiledTemplate += '} else {\n';
    compiledTemplate += '\tenv = nunjucks.currentEnv;\n';
    compiledTemplate += '}\n';
    if (pathToConfigure) {
        compiledTemplate += 'var configure = require("' + slash(path.relative(this.context, pathToConfigure)) + '")(env);\n';
    }




    // =========================================================================
    // Find template dependencies within nunjucks (extends, import, include etc)
    // =========================================================================
    //
    // Create an object on nunjucks to hold the template dependencies so that they persist
    // when this loader compiles multiple templates.
    compiledTemplate += 'var dependencies = nunjucks.webpackDependencies || (nunjucks.webpackDependencies = {});\n';

    var templateReg = /env\.getTemplate\(\"(.*?)\"/g;
    var match;

    // Create an object to store references to the dependencies that have been included - this ensures that a template
    // dependency is only written once per file, even if it is used multiple times.
    var required = {};

    // Iterate over the template dependencies
    while (match = templateReg.exec(nunjucksCompiledStr)) {
        var templateRef = match[1];
        if (!required[templateRef]) {
            // Require the dependency by name, so it gets bundled by webpack
            compiledTemplate += 'dependencies["' + templateRef + '"] = require( "' + templateRef + '" );\n';
            required[templateRef] = true;
        }
    }



    compiledTemplate += '\n\n\n\n';

    // Include a shim module (by reference rather than inline) that modifies the nunjucks runtime to work with the loader.
    compiledTemplate += 'var shim = require("' + slash(path.resolve(this.context, __dirname + '/runtime-shim')) + '");\n';
    compiledTemplate += '\n\n';

    // Write the compiled template string
    compiledTemplate += nunjucksCompiledStr + '\n';

    compiledTemplate += '\n\n';

    // export the shimmed module
    compiledTemplate += 'module.exports = shim(nunjucks, env, nunjucks.nunjucksPrecompiled["' + name + '"] , dependencies)';

    return compiledTemplate;
};