mongoDB中批量修改字段

// 为每一个文章文档新增一个image_count字段，用于记录此文章包含的图片个数

db['test.articles'].find({'title':'wfc test'}).forEach( function(thisArticle){

    // 这里要强制转为整形，否则会变成浮点数

    // 要用NumberInt转换为整形，用parseInt得到依然是浮点数

    imageCount = NumberInt( thisArticle['article_images'].length )

    db['test.articles'].update({'_id':thisArticle['_id']}, {$set:{'image_count':imageCount}} )

   })



// 比较精简干练的写法

db.test.articles.find({'title':'wfc test'}).forEach( function(thisArticle){

    thisArticle.image_count = NumberInt( thisArticle.article_images.length )

    db.test.articles.save(thisArticle)

  })



// 将文档的字段放入嵌套数组后，再删除该字段(数据结构修改)    

db['test.game'].find({'article_image':{$exists:0}}).forEach( function(thisArticle){

    articleImage = {'remote':thisArticle.game_icon, 'local':thisArticle.game_local_icon,

                    'original':thisArticle.game_remote_icon, 'upload':thisArticle.icon_upload}

    thisArticle.image_upload = thisArticle.icon_upload

    thisArticle.modify_time = thisArticle.spider_time

    thisArticle.article_image = []

    thisArticle.article_image.push(articleImage)

    delete thisArticle.game_icon

    delete thisArticle.game_local_icon

    delete thisArticle.game_remote_icon

    delete thisArticle.icon_upload

    db['test.game'].save(thisArticle)

})



// 按名称分组统计

db['test.articles'].group({

    key:{'name':1},

    condition:{'name':{$exists:1}},

    $reduce:function(curr, result) {

        result.total += 1

    },

    initial:{total:0},

})