node.js学习笔记（28） node-orm进阶三-白红宇

也许你想监听Model实例的创建、修改、获取或者删除，那么正好node-rom为Model定义了一系列事件。

afterLoad : (no parameters) Right after loading and preparing an instance to be used;

afterAutoFetch : (no parameters) Right after auto-fetching associations (if any), it will trigger regardless of having associations or not;

beforeSave : (no parameters) Right before trying to save;

afterSave : (bool success) Right after saving;

beforeCreate : (no parameters) Right before trying to save a new instance (prior to beforeSave);

afterCreate : (bool success) Right after saving a new instance;

beforeRemove : (no parameters) Right before trying to remove an instance;

afterRemove : (bool success) Right after removing an instance;

beforeValidation : (no parameters) Before all validations and prior to beforeCreate and beforeSave;

Node-orm将这些events定义为hook，钩子。

钩子实际上是一个处理消息的程序段，通过系统调用，把它挂入系统。每当特定的消息发出，在没有到达目的窗口前，钩子程序就先捕获该消息，亦即钩子函数先得到控制权。这时钩子函数即可以加工处理（改变）该消息，也可以不作处理而继续传递该消息，还可以强制结束消息的传递。

这些事件刚好可以为对model实例增删改查的前后进行拦截，然后对model实例做一些加工处理。因此，钩子这个名字正合适。

这些事件都可以通过this来调用model实例本身。

var Person = db.define("person", {    name    : String,    surname : String}, {    hooks: {        beforeCreate: function (next) {            console.log(this.name);            next();        }    }});

一共9个事件，不是before*就是after*。但从一组来看，先后顺序很好区分，比如beforeCreate和afterCreate，分别是在insert的一前一后。

但是insert并不是仅仅关联beforeCreate和afterCreate这么简单，它还关联afterLoad、beforeVlidation、beforeSave和afterSave，那么谁先谁后呢？

通过程序来区分吧。

hook-insert.js:

var orm = require("orm");orm.connect('mysql://root:root@localhost:3306/nodejs', function(err, db){    if (err) throw err;    var User = db.define("user", {        id          :{type:'serial', mapsTo:'id', unique:true, size:11},        name        :{type:'text', mapsTo:'name'},        username    :{type:'text', mapsTo:'username'},        password    :{type:'text', mapsTo:'password'},        birthday    :{type:'date', mapsTo:'birthday', time:true}    },{        validations:{            username:orm.enforce.unique('The username is already existed.')        },        hooks:{            afterLoad : function(next){                console.log('This is afterLoad');                next();            },            afterAutoFetch : function(next){                console.log('This is afterAutoFetch')                next();            },            beforeSave:function(next){                console.log('This is beforeSave')                next();            },            afterSave:function(success){                console.log('This is afterSave')            },            beforeCreate :function(next){                console.log('This is beforeCreate')                next();            },            afterCreate :function(success){                console.log('This is afterCreate')            },            beforeRemove :function(next){                console.log('This is beforeRemove')                next();            },            afterRemove :function(success){                console.log('This is afterRemove')            },            beforeValidation :function(next){                console.log('This is beforeValidation')                next();            }        }    });    var user = new User(        {            name:'e',            username:'ee',            password:'eee',            birthday:'2010-10-10 10:10:10'        }    );    user.save(function(err){        if(err){            console.log(err);        }    });});

运行hook-insert：

node hook-insert.jsThis is afterLoadThis is afterAutoFetchThis is beforeValidationThis is beforeCreateThis is beforeSaveThis is afterCreateThis is afterSave

hook-load.js:

var orm = require("orm");orm.connect('mysql://root:root@localhost:3306/nodejs', function(err, db){    if (err) throw err;    var User = db.define("user", {        id          :{type:'serial', mapsTo:'id', unique:true, size:11},        name        :{type:'text', mapsTo:'name'},        username    :{type:'text', mapsTo:'username'},        password    :{type:'text', mapsTo:'password'},        birthday    :{type:'date', mapsTo:'birthday', time:true}    },{        validations:{            username:orm.enforce.unique('The username is already existed.')        },        hooks:{            afterLoad : function(next){                console.log('This is afterLoad');                next();            },            afterAutoFetch : function(next){                console.log('This is afterAutoFetch')                next();            },            beforeSave:function(next){                console.log('This is beforeSave')                next();            },            afterSave:function(success){                console.log('This is afterSave')            },            beforeCreate :function(next){                console.log('This is beforeCreate')                next();            },            afterCreate :function(success){                console.log('This is afterCreate')            },            beforeRemove :function(next){                console.log('This is beforeRemove')                next();            },            afterRemove :function(success){                console.log('This is afterRemove')            },            beforeValidation :function(next){                console.log('This is beforeValidation')                next();            }        }    });    User.find({username:'ee'}, function(err, items) {        for(var i=0;i

运行hook-load.js:

node hook-load.jsThis is afterLoadThis is afterAutoFetch{"id":8,"name":"e","username":"ee","password":"eee","birthday":"2010-10-10T02:10:10.000Z"}

hook-update.js:

var orm = require("orm");orm.connect('mysql://root:root@localhost:3306/nodejs', function(err, db){    if (err) throw err;    var User = db.define("user", {        id          :{type:'serial', mapsTo:'id', unique:true, size:11},        name        :{type:'text', mapsTo:'name'},        username    :{type:'text', mapsTo:'username'},        password    :{type:'text', mapsTo:'password'},        birthday    :{type:'date', mapsTo:'birthday', time:true}    },{        validations:{            username:orm.enforce.unique('The username is already existed.')        },        hooks:{            afterLoad : function(next){                console.log('This is afterLoad');                next();            },            afterAutoFetch : function(next){                console.log('This is afterAutoFetch')                next();            },            beforeSave:function(next){                console.log('This is beforeSave')                next();            },            afterSave:function(success){                console.log('This is afterSave')            },            beforeCreate :function(next){                console.log('This is beforeCreate')                next();            },            afterCreate :function(success){                console.log('This is afterCreate')            },            beforeRemove :function(next){                console.log('This is beforeRemove')                next();            },            afterRemove :function(success){                console.log('This is afterRemove')            },            beforeValidation :function(next){                console.log('This is beforeValidation')                next();            }        }    });    User.find({username:'ee'}, function(err, items) {        for(var i=0;i

运行hook-update.js:

node hook-update.jsThis is afterLoadThis is afterAutoFetchThis is beforeValidationThis is beforeSaveThis is afterSave

hook-delete.js:

var orm = require("orm");orm.connect('mysql://root:root@localhost:3306/nodejs', function(err, db){    if (err) throw err;    var User = db.define("user", {        id          :{type:'serial', mapsTo:'id', unique:true, size:11},        name        :{type:'text', mapsTo:'name'},        username    :{type:'text', mapsTo:'username'},        password    :{type:'text', mapsTo:'password'},        birthday    :{type:'date', mapsTo:'birthday', time:true}    },{        validations:{            username:orm.enforce.unique('The username is already existed.')        },        hooks:{            afterLoad : function(next){                console.log('This is afterLoad');                next();            },            afterAutoFetch : function(next){                console.log('This is afterAutoFetch')                next();            },            beforeSave:function(next){                console.log('This is beforeSave')                next();            },            afterSave:function(success){                console.log('This is afterSave')            },            beforeCreate :function(next){                console.log('This is beforeCreate')                next();            },            afterCreate :function(success){                console.log('This is afterCreate')            },            beforeRemove :function(next){                console.log('This is beforeRemove')                next();            },            afterRemove :function(success){                console.log('This is afterRemove')            },            beforeValidation :function(next){                console.log('This is beforeValidation')                next();            }        }    });    User.find({username:'ff'}, function(err, items) {        for(var i=0;i

运行hook-delete.js:

node hook-delete.jsThis is afterLoadThis is afterAutoFetchThis is beforeRemoveThis is afterRemove

从上面增、删、改、查四个程序的运行结果不难看出：

跟insert有关的事件有7个，按顺序分别是afterLoad、afterAutoFetch、beforeValidation、beforeCreate、beforeSave、afterCreate、afterSave。

跟udpate有关的事件有5个，按顺序分别是afterLoad、afterAutoFetch、beforeValidation、beforeSave、afterSave。

跟selete有关的事件有2个，按顺序分别是afterLoad、afterAutoFetch。

跟delete有关的事件有2个，按顺序分别是beforeRemove、afterRemove。

另外，除了afterSave、afterCreate和afterRemove，其他事件都有next参数，next是一个回调函数用于执行下一步，如果没next，程序将就此终止。