问题
Let's assume i have Three models files author, article and publications
My model.js are as follows
//author.js
attributes : {
name : 'string',
articles : {
collection : 'article',
via : 'authors'
}
}
//article.js
attributes : {
name : 'string',
authors : {
collection : 'author',
via : 'articles'
},
publication : {
model : 'publication'
}
}
//publication.js
attributes : {
name : 'string',
articles : {
collection : 'article',
via : 'publication'
}
}
From the above association if i GET an author by his ID,it will return the author details and then the articles which he wrote, what i also want is the articles must show the association which it has with publication model. i couldn't achieve any suggestions please.
I tried the sails documentation but there i can find only one layer of association
i'm using mongodb as my database
Thanks in advance
回答1:
Sorry to say, but right now there is not way to do it in a single database query. You can do it in two or more database queries. Example would be like this.
Author
.findOne(2)
.populate('articles')
.exec(function (err, itemPost){
// some error handling
async.map(itemPost.articles,
function (article, callback){
Article
.findOne(article.id)
.populateAll()
.exec(function (errArticles, articleItem){
if(errArticles){return callback(errArticles)};
callback(null, articleItem);
});
},
function (errFromIterator, results){
if(errFromIterator){res.serverError()};
var itemPostToJSON = itemPost.toJSON();
itemPostToJSON.comments = results;
var clone = _.clone(itemPostToJSON);
res.send(clone);
}
)
});
Looks like people have already discussed this issue a lot. I giving you one of their discussion link. My solution is also taken from there. Hope it helps.
[N. B. : I didn't run this code. So can't say if their is a mistake or not. Looked like it's okay so I referred it to you.]
来源:https://stackoverflow.com/questions/30324302/sails-js-complex-many-to-many-association