mongodb 实现关系型数据库中查询某一列 的效果

Posted 2020-09-30 slgkaifa

近期在tornado\mongodb\ansible

mongodb中有个find()方法非常牛逼,能够将集合中全部的表都传出来,一開始我这么写

class Module_actionHandler(tornado.web.RequestHandler):
    def get(self, *args, **kwargs):
        coll = self.application.db.waitfish
        hosts = coll.find({}, {'hostname':1,"_id":0})
        modulenames = ['ping', 'setup', 'copy']
        self.render(
            "module_action.html",
            hosts = hosts,
            modulenames = modulenames,
        )

然后在模板中:

<select name="hostname">
                {% for host in hosts %}
                <option name="{{ host['hostname'] }}" >{{ host['hostname'] }}</option>
                {% end %}
</select>

后来想了想find()方法是找出全部的表,这太伤不起了..

于是又去看了度娘,基本上都是列出一大堆查询命令,好多中方法的.

最后我还是选了这一种:

class Module_actionHandler(tornado.web.RequestHandler):
    def get(self, *args, **kwargs):
        coll = self.application.db.waitfish
        hosts = coll.find({}, {'hostname':1,"_id":0})#解释一下,这里hostname:1 表示返回hostname列,因为_id列每次都返回所以用0禁用掉,模板还一样
        modulenames = ['ping', 'setup', 'copy']
        self.render(
            "module_action.html",
            hosts = hosts,
            modulenames = modulenames,
        )