node.js学习笔记（28） node-orm进阶三

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.js
This is afterLoad
This is afterAutoFetch
This is beforeValidation
This is beforeCreate
This is beforeSave
This is afterCreate
This 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<items.length;i++){
            console.log(JSON.stringify(items[i]));
        }
    });

});

运行hook-load.js:

node hook-load.js
This is afterLoad
This 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<items.length;i++){
            items[i].username = 'ff';
            items[i].save();
        }
    });

});

运行hook-update.js:

node hook-update.js
This is afterLoad
This is afterAutoFetch
This is beforeValidation
This is beforeSave
This 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<items.length;i++){
            items[i].remove();
        }
    });

});

运行hook-delete.js:

node hook-delete.js
This is afterLoad
This is afterAutoFetch
This is beforeRemove
This 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。

时间： 2024-08-11 00:39:13

node.js学习笔记（28） node-orm进阶三

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