loopback-datasource-juggler/lib/relations.js

310 lines
10 KiB
JavaScript

/**
* Dependencies
*/
var i8n = require('inflection');
var defineScope = require('./scope.js').defineScope;
var ModelBaseClass = require('./model.js');
module.exports = Relation;
function Relation() {
}
Relation.relationNameFor = function relationNameFor(foreignKey) {
for (var rel in this.relations) {
if (this.relations[rel].type === 'belongsTo' && this.relations[rel].keyFrom === foreignKey) {
return rel;
}
}
};
/**
* Declare hasMany relation
*
* @param {Relation} anotherClass - class to has many
* @param {Object} params - configuration {as:, foreignKey:}
* @example `User.hasMany(Post, {as: 'posts', foreignKey: 'authorId'});`
*/
Relation.hasMany = function hasMany(anotherClass, params) {
var thisClass = this, thisClassName = this.modelName;
params = params || {};
if (typeof anotherClass === 'string') {
params.as = anotherClass;
if (params.model) {
anotherClass = params.model;
} else {
var anotherClassName = i8n.singularize(anotherClass).toLowerCase();
for(var name in this.dataSource.models) {
if (name.toLowerCase() === anotherClassName) {
anotherClass = this.dataSource.models[name];
}
}
}
}
var methodName = params.as || i8n.camelize(anotherClass.pluralModelName, true);
var fk = params.foreignKey || i8n.camelize(thisClassName + '_id', true);
var idName = this.dataSource.idName(this.modelName) || 'id';
this.relations[methodName] = {
type: 'hasMany',
keyFrom: idName,
keyTo: fk,
modelTo: anotherClass,
multiple: true
};
// each instance of this class should have method named
// pluralize(anotherClass.modelName)
// which is actually just anotherClass.all({where: {thisModelNameId: this[idName]}}, cb);
var scopeMethods = {
findById: find,
destroy: destroy
};
if (params.through) {
var fk2 = i8n.camelize(anotherClass.modelName + '_id', true);
scopeMethods.create = function create(data, done) {
if (typeof data !== 'object') {
done = data;
data = {};
}
if ('function' !== typeof done) {
done = function() {};
}
var self = this;
var id = this[idName];
anotherClass.create(data, function(err, ac) {
if (err) return done(err, ac);
var d = {};
d[params.through.relationNameFor(fk)] = self;
d[params.through.relationNameFor(fk2)] = ac;
params.through.create(d, function(e) {
if (e) {
ac.destroy(function() {
done(e);
});
} else {
done(err, ac);
}
});
});
};
scopeMethods.add = function(acInst, done) {
var data = {};
var query = {};
query[fk] = this[idName];
data[params.through.relationNameFor(fk)] = this;
query[fk2] = acInst[idName] || acInst;
data[params.through.relationNameFor(fk2)] = acInst;
params.through.findOrCreate({where: query}, data, done);
};
scopeMethods.remove = function(acInst, done) {
var self = this;
var q = {};
q[fk2] = acInst[idName] || acInst;
params.through.findOne({where: q}, function(err, d) {
if (err) {
return done(err);
}
if (!d) {
return done();
}
d.destroy(done);
});
};
delete scopeMethods.destroy;
}
defineScope(this.prototype, params.through || anotherClass, methodName, function () {
var filter = {};
filter.where = {};
filter.where[fk] = this[idName];
if (params.through) {
filter.collect = i8n.camelize(anotherClass.modelName, true);
filter.include = filter.collect;
}
return filter;
}, scopeMethods);
if (!params.through) {
// obviously, anotherClass should have attribute called `fk`
anotherClass.dataSource.defineForeignKey(anotherClass.modelName, fk, this.modelName);
}
function find(id, cb) {
anotherClass.findById(id, function (err, inst) {
if (err) return cb(err);
if (!inst) return cb(new Error('Not found'));
if (inst[fk] && inst[fk].toString() == this[idName].toString()) {
cb(null, inst);
} else {
cb(new Error('Permission denied'));
}
}.bind(this));
}
function destroy(id, cb) {
var self = this;
anotherClass.findById(id, function (err, inst) {
if (err) return cb(err);
if (!inst) return cb(new Error('Not found'));
if (inst[fk] && inst[fk].toString() == self[idName].toString()) {
inst.destroy(cb);
} else {
cb(new Error('Permission denied'));
}
});
}
};
/**
* Declare belongsTo relation
*
* @param {Class} anotherClass - class to belong
* @param {Object} params - configuration {as: 'propertyName', foreignKey: 'keyName'}
*
* **Usage examples**
* Suppose model Post have a *belongsTo* relationship with User (the author of the post). You could declare it this way:
* Post.belongsTo(User, {as: 'author', foreignKey: 'userId'});
*
* When a post is loaded, you can load the related author with:
* post.author(function(err, user) {
* // the user variable is your user object
* });
*
* The related object is cached, so if later you try to get again the author, no additional request will be made.
* But there is an optional boolean parameter in first position that set whether or not you want to reload the cache:
* post.author(true, function(err, user) {
* // The user is reloaded, even if it was already cached.
* });
*
* This optional parameter default value is false, so the related object will be loaded from cache if available.
*/
Relation.belongsTo = function (anotherClass, params) {
params = params || {};
if ('string' === typeof anotherClass) {
params.as = anotherClass;
if (params.model) {
anotherClass = params.model;
} else {
var anotherClassName = anotherClass.toLowerCase();
for(var name in this.dataSource.models) {
if (name.toLowerCase() === anotherClassName) {
anotherClass = this.dataSource.models[name];
}
}
}
}
var idName = this.dataSource.idName(this.modelName) || 'id';
var methodName = params.as || i8n.camelize(anotherClass.modelName, true);
var fk = params.foreignKey || methodName + 'Id';
this.relations[methodName] = {
type: 'belongsTo',
keyFrom: fk,
keyTo: idName,
modelTo: anotherClass,
multiple: false
};
this.dataSource.defineForeignKey(this.modelName, fk, anotherClass.modelName);
this.prototype['__finders__'] = this.prototype['__finders__'] || {};
this.prototype['__finders__'][methodName] = function (id, cb) {
if (id === null) {
cb(null, null);
return;
}
anotherClass.findById(id, function (err,inst) {
if (err) return cb(err);
if (!inst) return cb(null, null);
if (inst[idName] === this[fk]) {
cb(null, inst);
} else {
cb(new Error('Permission denied'));
}
}.bind(this));
};
this.prototype[methodName] = function (refresh, p) {
if (arguments.length === 1) {
p = refresh;
refresh = false;
} else if (arguments.length > 2) {
throw new Error('Method can\'t be called with more than two arguments');
}
var self = this;
var cachedValue;
if (!refresh && this.__cachedRelations && (typeof this.__cachedRelations[methodName] !== 'undefined')) {
cachedValue = this.__cachedRelations[methodName];
}
if (p instanceof ModelBaseClass) { // acts as setter
this[fk] = p[idName];
this.__cachedRelations[methodName] = p;
} else if (typeof p === 'function') { // acts as async getter
if (typeof cachedValue === 'undefined') {
this.__finders__[methodName].apply(self, [this[fk], function(err, inst) {
if (!err) {
self.__cachedRelations[methodName] = inst;
}
p(err, inst);
}]);
return this[fk];
} else {
p(null, cachedValue);
return cachedValue;
}
} else if (typeof p === 'undefined') { // acts as sync getter
return this[fk];
} else { // setter
this[fk] = p;
delete this.__cachedRelations[methodName];
}
};
};
/**
* Many-to-many relation
*
* Post.hasAndBelongsToMany('tags'); creates connection model 'PostTag'
*/
Relation.hasAndBelongsToMany = function hasAndBelongsToMany(anotherClass, params) {
params = params || {};
var models = this.dataSource.models;
if ('string' === typeof anotherClass) {
params.as = anotherClass;
if (params.model) {
anotherClass = params.model;
} else {
anotherClass = lookupModel(i8n.singularize(anotherClass)) ||
anotherClass;
}
if (typeof anotherClass === 'string') {
throw new Error('Could not find "' + anotherClass + '" relation for ' + this.modelName);
}
}
if (!params.through) {
var name1 = this.modelName + anotherClass.modelName;
var name2 = anotherClass.modelName + this.modelName;
params.through = lookupModel(name1) || lookupModel(name2) ||
this.dataSource.define(name1);
}
params.through.belongsTo(this);
params.through.belongsTo(anotherClass);
this.hasMany(anotherClass, {as: params.as, through: params.through});
function lookupModel(modelName) {
var lookupClassName = modelName.toLowerCase();
for (var name in models) {
if (name.toLowerCase() === lookupClassName) {
return models[name];
}
}
}
};