loopback-datasource-juggler/lib/scope.js

288 lines
7.8 KiB
JavaScript

var i8n = require('inflection');
var utils = require('./utils');
var defineCachedRelations = utils.defineCachedRelations;
/**
* Module exports
*/
exports.defineScope = defineScope;
exports.mergeQuery = mergeQuery;
function ScopeDefinition(definition) {
this.sourceModel = definition.sourceModel;
this.targetModel = definition.targetModel || definition.sourceModel;
this.name = definition.name;
this.params = definition.params;
this.methods = definition.methods;
}
ScopeDefinition.prototype.related = function(receiver, scopeParams, condOrRefresh, cb) {
var name = this.name;
var self = receiver;
var actualCond = {};
var actualRefresh = false;
var saveOnCache = true;
if (arguments.length === 3) {
cb = condOrRefresh;
} else if (arguments.length === 4) {
if (typeof condOrRefresh === 'boolean') {
actualRefresh = condOrRefresh;
} else {
actualCond = condOrRefresh;
actualRefresh = true;
saveOnCache = false;
}
} else {
throw new Error('Method can be only called with one or two arguments');
}
if (!self.__cachedRelations || self.__cachedRelations[name] === undefined
|| actualRefresh) {
// It either doesn't hit the cache or refresh is required
var params = mergeQuery(actualCond, scopeParams);
return this.targetModel.find(params, function (err, data) {
if (!err && saveOnCache) {
defineCachedRelations(self);
self.__cachedRelations[name] = data;
}
cb(err, data);
});
} else {
// Return from cache
cb(null, self.__cachedRelations[name]);
}
}
/**
* Define a scope to the class
* @param {Model} cls The class where the scope method is added
* @param {Model} targetClass The class that a query to run against
* @param {String} name The name of the scope
* @param {Object|Function} params The parameters object for the query or a function
* to return the query object
* @param methods An object of methods keyed by the method name to be bound to the class
*/
function defineScope(cls, targetClass, name, params, methods) {
// collect meta info about scope
if (!cls._scopeMeta) {
cls._scopeMeta = {};
}
// only makes sense to add scope in meta if base and target classes
// are same
if (cls === targetClass) {
cls._scopeMeta[name] = params;
} else {
if (!targetClass._scopeMeta) {
targetClass._scopeMeta = {};
}
}
var definition = new ScopeDefinition({
sourceModel: cls,
targetModel: targetClass,
name: name,
params: params,
methods: methods
});
// Define a property for the scope
Object.defineProperty(cls, name, {
enumerable: false,
configurable: true,
/**
* This defines a property for the scope. For example, user.accounts or
* User.vips. Please note the cls can be the model class or prototype of
* the model class.
*
* The property value is function. It can be used to query the scope,
* such as user.accounts(condOrRefresh, cb) or User.vips(cb). The value
* can also have child properties for create/build/delete. For example,
* user.accounts.create(act, cb).
*
*/
get: function () {
var self = this;
var f = function(condOrRefresh, cb) {
if(arguments.length === 1) {
definition.related(self, f._scope, condOrRefresh);
} else {
definition.related(self, f._scope, condOrRefresh, cb);
}
};
f._scope = typeof definition.params === 'function' ?
definition.params.call(self) : definition.params;
f._targetClass = definition.targetModel.modelName;
if (f._scope.collect) {
f._targetClass = i8n.capitalize(f._scope.collect);
}
f.build = build;
f.create = create;
f.destroyAll = destroyAll;
for (var i in definition.methods) {
f[i] = definition.methods[i].bind(self);
}
// Define scope-chaining, such as
// Station.scope('active', {where: {isActive: true}});
// Station.scope('subway', {where: {isUndeground: true}});
// Station.active.subway(cb);
Object.keys(targetClass._scopeMeta).forEach(function (name) {
Object.defineProperty(f, name, {
enumerable: false,
get: function () {
mergeQuery(f._scope, targetClass._scopeMeta[name]);
return f;
}
});
}.bind(self));
return f;
}
});
// Wrap the property into a function for remoting
var fn = function () {
// primaryObject.scopeName, such as user.accounts
var f = this[name];
// set receiver to be the scope property whose value is a function
f.apply(this[name], arguments);
};
cls['__get__' + name] = fn;
var fn_create = function () {
var f = this[name].create;
f.apply(this[name], arguments);
};
cls['__create__' + name] = fn_create;
var fn_delete = function () {
var f = this[name].destroyAll;
f.apply(this[name], arguments);
};
cls['__delete__' + name] = fn_delete;
/*
* Extracting fixed property values for the scope from the where clause into
* the data object
*
* @param {Object} The data object
* @param {Object} The where clause
*/
function setScopeValuesFromWhere(data, where) {
for (var i in where) {
if (i === 'and') {
// Find fixed property values from each subclauses
for (var w = 0, n = where[i].length; w < n; w++) {
setScopeValuesFromWhere(data, where[i][w]);
}
continue;
}
var prop = targetClass.definition.properties[i];
if (prop) {
var val = where[i];
if (typeof val !== 'object' || val instanceof prop.type
|| prop.type.name === 'ObjectID') // MongoDB key
{
// Only pick the {propertyName: propertyValue}
data[i] = where[i];
}
}
}
}
// and it should have create/build methods with binded thisModelNameId param
function build(data) {
data = data || {};
// Find all fixed property values for the scope
var where = (this._scope && this._scope.where) || {};
setScopeValuesFromWhere(data, where);
return new targetClass(data);
}
function create(data, cb) {
if (typeof data === 'function') {
cb = data;
data = {};
}
this.build(data).save(cb);
}
/*
Callback
- The callback will be called after all elements are destroyed
- For every destroy call which results in an error
- If fetching the Elements on which destroyAll is called results in an error
*/
function destroyAll(cb) {
var where = (this._scope && this._scope.where) || {};
targetClass.destroyAll(where, cb);
}
return definition;
}
/*!
* Merge query parameters
* @param {Object} base The base object to contain the merged results
* @param {Object} update The object containing updates to be merged
* @returns {*|Object} The base object
* @private
*/
function mergeQuery(base, update) {
if (!update) {
return;
}
base = base || {};
if (update.where && Object.keys(update.where).length > 0) {
if (base.where && Object.keys(base.where).length > 0) {
base.where = {and: [base.where, update.where]};
} else {
base.where = update.where;
}
}
// Merge inclusion
if (update.include) {
if (!base.include) {
base.include = update.include;
} else {
var saved = base.include;
base.include = {};
base.include[update.include] = [saved];
}
}
if (update.collect) {
base.collect = update.collect;
}
// overwrite order
if (update.order) {
base.order = update.order;
}
// overwrite pagination
if (update.limit !== undefined) {
base.limit = update.limit;
}
if (update.skip !== undefined) {
base.skip = update.skip;
}
if (update.offset !== undefined) {
base.offset = update.offset;
}
// Overwrite fields
if (update.fields !== undefined) {
base.fields = update.fields;
}
return base;
}