hexo post.create的过程分析

hexo的post创建过程

要讲hexo的post.create先要看它的传入参数。

this.post.create(data, args.r || args.replace)

data定义如下：

var data = {
    title: args._.pop(),//标题
    //这里layout就是可以通过 hexo n  title layout获取
    layout: args._.length ? args._[0] : this.config.default_layout,
    slug: args.s || args.slug,//为undefined
    path: args.p || args.path//为undefined
  };

hexo/post.js：

Post.prototype.create = function(data, replace, callback){
  //callback没传入 replace 为undefined
  if (!callback && typeof replace === 'function'){
    callback = replace;
    replace = false;
  }

  var ctx = this.context;//为hexo对象
  var config = ctx.config; //_.clone(defaultConfig) _:lodash库 浅拷贝
  //https://github.com/lodash

  //slugize为hexo_util库中的函数
  data.slug = slugize((data.slug || data.title).toString(), {transform: config.filename_case});
  data.layout = (data.layout || config.default_layout).toLowerCase();
  data.date = data.date ? moment(data.date) : moment();//获取当前时间 moment库

  return Promise.all([
    // Get the post path
    ctx.execFilter('new_post_path', data, {
      args: [replace],
      context: ctx
    }),
    // Get the scaffold
    this._getScaffold(data.layout)
  ]).spread(function(path, scaffold){
    // Split data part from the raw scaffold
    var split = yfm.split(scaffold);
    var separator = split.separator || '---';
    var jsonMode = separator[0] === ';';
    var frontMatter = prepareFrontMatter(_.clone(data));
    var content = '';

    // Compile front-matter with data
    var renderedData = swig.compile(split.data)(frontMatter);

    // Parse front-matter
    var compiled;

    if (jsonMode){
      compiled = JSON.parse('{' + renderedData + '}');
    } else {
      compiled = yaml.load(renderedData);
    }

    // Add data which are not in the front-matter
    var keys = Object.keys(data);
    var key = '';
    var obj = compiled;

    for (var i = 0, len = keys.length; i < len; i++){
      key = keys[i];

      if (!preservedKeys[key] && obj[key] == null){
        obj[key] = data[key];
      }
    }

    // Prepend the separator
    if (split.prefixSeparator) content += separator + '\n';

    content += yfm.stringify(obj, {
      mode: jsonMode ? 'json' : ''
    });

    // Concat content
    content += split.content;

    if (data.content){
      content += '\n' + data.content;
    }

    var result = {
      path: path,
      content: content
    };

    return Promise.all([
      // Write content to file
      fs.writeFile(path, content),//写入内容
      // Create asset folder
      createAssetFolder(path, config.post_asset_folder)
    ]).then(function(){

      //http://biyeah.iteye.com/blog/1308954
      ctx.emit('new', result);
    }).thenReturn(result);
  }).nodeify(callback);
}

ctx.execFilter('new_post_path', data, {
     args: [replace],
     context: ctx
   })

执行new_post_path类型的过滤器,hexo/index.js代码如下：

Hexo.prototype.execFilter = function(type, data, options){
 		return this.extend.filter.exec(type, data, options);
};

路径hexo/extend/filter.js：

Filter.prototype.exec = function(type, data, options){
	  options = options || {};

	  var filters = this.list(type);
	  var ctx = options.context;//hexo实例对象
	  var args = options.args || []; //上面的[replace]

	  args.unshift(data);

	  return Promise.each(filters, function(filter){
	    return Promise.method(filter).apply(ctx, args).then(function(result){
	      args[0] = result == null ? data : result;
	      return args[0];
	    });
	  }).then(function(){
	    return args[0];
	  });
};

这里我们执行的是new_post_path的filter:
文件路径为hexo/lib/plugins/filter/new_post_path.js

function newPostPathFilter(data, replace){
  /* jshint validthis: true */
  data = data || {};

  var sourceDir = this.source_dir;
  var draftDir = pathFn.join(sourceDir, '_drafts');
  var postDir = pathFn.join(sourceDir, '_posts');
  var config = this.config;
  var newPostName = config.new_post_name;
  var permalinkDefaults = config.permalink_defaults;
  var path = data.path;
  var layout = data.layout;
  var slug = data.slug;
  var target = '';

  if (!permalink || permalink.rule !== newPostName){
    permalink = new Permalink(newPostName);
  }
  //path为undefined
  if (path){
    switch (layout){
      case 'page':
        target = pathFn.join(sourceDir, path);
        break;

      case 'draft':
        target = pathFn.join(draftDir, path);
        break;

      default:
        target = pathFn.join(postDir, path);
    }
  } else if (slug){
    switch (layout){
      case 'page':
        target = pathFn.join(sourceDir, slug, 'index');
        break;

      case 'draft':
        target = pathFn.join(draftDir, slug);
        break;

      default:
        var date = moment(data.date || Date.now());
        var keys = Object.keys(data);
        var key = '';

        var filenameData = {
          year: date.format('YYYY'),
          month: date.format('MM'),
          i_month: date.format('M'),
          day: date.format('DD'),
          i_day: date.format('D'),
          title: slug
        };

        for (var i = 0, len = keys.length; i < len; i++){
          key = keys[i];
          if (!reservedKeys[key]) filenameData[key] = data[key];
        }

        target = pathFn.join(postDir, permalink.stringify(
          _.defaults(filenameData, permalinkDefaults)));
    }
  } else {
    return Promise.reject(new TypeError('Either data.path or data.slug is required!'));
  }

  if (!pathFn.extname(target)){
    target += pathFn.extname(newPostName) || '.md';
  }

  if (replace){
    return Promise.resolve(target);
  } else {
    return fs.ensurePath(target);
  }
}