Mongoose介绍

jieforest

Error handling

If any middleware calls next or done with an Error instance, the flow is interrupted, and the error is passed to the function passed as an argument.

For example:

1. schema.pre('save', function (next) {
   
2.   // something goes wrong
   
3.   next(new Error('something went wrong'));
   
4. });
   
5. 
   
6. // later...
   
7. 
   
8. myModel.save(function (err) {
   
9.   // err can come from a middleware
   
10. });

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jieforest

Intercepting and mutating method arguments

You can intercept method arguments via middleware.

For example, this would allow you to broadcast changes about your Documents every time someone sets a path in your Document to a new value:

1. schema.pre('set', function (next, path, val, typel) {
   
2.   // `this` is the current Document
   
3.   this.emit('set', path, val);
   
4. 
   
5.   // Pass control to the next pre
   
6.   next();
   
7. });

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Moreover, you can mutate the incoming method arguments so that subsequent middleware see different values for those arguments. To do so, just pass the new values to next:

1. .pre(method, function firstPre (next, methodArg1, methodArg2) {
   
2.   // Mutate methodArg1
   
3.   next("altered-" + methodArg1.toString(), methodArg2);
   
4. })
   
5. 
   
6. // pre declaration is chainable
   
7. .pre(method, function secondPre (next, methodArg1, methodArg2) {
   
8.   console.log(methodArg1);
   
9.   // => 'altered-originalValOfMethodArg1'
   
10. 
    
11.   console.log(methodArg2);
    
12.   // => 'originalValOfMethodArg2'
    
13. 
    
14.   // Passing no arguments to `next` automatically passes along the current argument values
    
15.   // i.e., the following `next()` is equivalent to `next(methodArg1, methodArg2)`
    
16.   // and also equivalent to, with the example method arg
    
17.   // values, `next('altered-originalValOfMethodArg1', 'originalValOfMethodArg2')`
    
18.   next();
    
19. })

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jieforest

Schema gotcha

type, when used in a schema has special meaning within Mongoose. If your schema requires using type as a nested property you must use object notation:

1. 
   
2. new Schema({
   
3.     broken: { type: Boolean }
   
4.   , asset : {
   
5.         name: String
   
6.       , type: String // uh oh, it broke. asset will be interpreted as String
   
7.     }
   
8. });
   
9. 
   
10. new Schema({
    
11.     works: { type: Boolean }
    
12.   , asset : {
    
13.         name: String
    
14.       , type: { type: String } // works. asset is an object with a type property
    
15.     }
    
16. });

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jieforest

Contributing to Mongoose

Cloning the repository

Make a fork of mongoose, then clone it in your computer. The v3.x branch is for v3 development, the v2.x branch is for v2 development, and the master branch the next upcoming major release.

Guidelines

Before starting to write code, look for existing tickets or create one for your specific issue. That way you avoid working on something that might not be of interest or that has been addressed already in a different branch.
Write inline documentation for new methods or class members.
Write tests and make sure they pass.
Follow the general coding style of the rest of the project (comma first, etc).

jieforest

License
Copyright (c) 2010-2012 LearnBoost <dev@learnboost.com>

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the 'Software'), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED 'AS IS', WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

jieforest

over.