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Allow service factory functions to return promises #3295

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Allow service factory functions to return promises #3295

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61 changes: 45 additions & 16 deletions src/auto/injector.js
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Original file line number Diff line number Diff line change
Expand Up @@ -149,7 +149,7 @@ function annotate(fn) {
* @param {Object=} self The `this` for the invoked method.
* @param {Object=} locals Optional object. If preset then any argument names are read from this object first, before
* the `$injector` is consulted.
* @returns {*} the value returned by the invoked `fn` function.
* @returns {*} the value returned by the invoked `fn` function, or a promise if any injectable dependencies are themselves unresolved promises.
*/

/**
Expand Down Expand Up @@ -556,7 +556,10 @@ function createInjector(modulesToLoad) {
var args = [],
$inject = annotate(fn),
length, i,
key;
key,
hasPromisedDependencies = false,
invocationDeferredReturn,
dependenciesPromise;

for(i = 0, length = $inject.length; i < length; i++) {
key = $inject[i];
Expand All @@ -568,27 +571,53 @@ function createInjector(modulesToLoad) {
? locals[key]
: getService(key)
);

// make note if we discover a dependency which is currently a promise.
// this will trigger a deferred return value from this function and
// delay the invocation until all promised dependencies have been resolved.
if(!hasPromisedDependencies && args[i] && args[i].then && typeof args[i].then == "function") {
hasPromisedDependencies = true;
}
}
if (!fn.$inject) {
// this means that we must be an array.
fn = fn[length];
}

// this will either be invoked immediately or
// once all dependencies have been fulfilled.
function performInvocation(fn, self, args) {
// Performance optimization: http://jsperf.com/apply-vs-call-vs-invoke
switch (self ? -1 : args.length) {
case 0: return fn();
case 1: return fn(args[0]);
case 2: return fn(args[0], args[1]);
case 3: return fn(args[0], args[1], args[2]);
case 4: return fn(args[0], args[1], args[2], args[3]);
case 5: return fn(args[0], args[1], args[2], args[3], args[4]);
case 6: return fn(args[0], args[1], args[2], args[3], args[4], args[5]);
case 7: return fn(args[0], args[1], args[2], args[3], args[4], args[5], args[6]);
case 8: return fn(args[0], args[1], args[2], args[3], args[4], args[5], args[6], args[7]);
case 9: return fn(args[0], args[1], args[2], args[3], args[4], args[5], args[6], args[7], args[8]);
case 10: return fn(args[0], args[1], args[2], args[3], args[4], args[5], args[6], args[7], args[8], args[9]);
default: return fn.apply(self, args);
}
}

// Performance optimization: http://jsperf.com/apply-vs-call-vs-invoke
switch (self ? -1 : args.length) {
case 0: return fn();
case 1: return fn(args[0]);
case 2: return fn(args[0], args[1]);
case 3: return fn(args[0], args[1], args[2]);
case 4: return fn(args[0], args[1], args[2], args[3]);
case 5: return fn(args[0], args[1], args[2], args[3], args[4]);
case 6: return fn(args[0], args[1], args[2], args[3], args[4], args[5]);
case 7: return fn(args[0], args[1], args[2], args[3], args[4], args[5], args[6]);
case 8: return fn(args[0], args[1], args[2], args[3], args[4], args[5], args[6], args[7]);
case 9: return fn(args[0], args[1], args[2], args[3], args[4], args[5], args[6], args[7], args[8]);
case 10: return fn(args[0], args[1], args[2], args[3], args[4], args[5], args[6], args[7], args[8], args[9]);
default: return fn.apply(self, args);
if(hasPromisedDependencies) {
// wrap all args in .when() for common interface, then use .all()
// to perform the invocation once all are resolved.
for(i = 0, length = args.length; i < length; i++) {
args[i] = cache['$q'].when(args[i]);
}
dependenciesPromise = cache['$q'].all(args);
invocationDeferredReturn = cache['$q'].defer();
dependenciesPromise.then(function(resolvedArgs){
invocationDeferredReturn.resolve(performInvocation(fn, self, resolvedArgs));
})
return invocationDeferredReturn.promise;
} else {
return performInvocation(fn, self, args);
}
}

Expand Down
106 changes: 106 additions & 0 deletions test/auto/injectorSpec.js
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Original file line number Diff line number Diff line change
Expand Up @@ -90,6 +90,27 @@ describe('injector', function() {

describe('invoke', function() {
var args;
var q, defer, deferred, promise, log;
var mockNextTick = {
nextTick: function(task) {
mockNextTick.queue.push(task);
},
queue: [],
flush: function() {
if (!mockNextTick.queue.length) throw new Error('Nothing to be flushed!');
while (mockNextTick.queue.length) {
var queue = mockNextTick.queue;
mockNextTick.queue = [];
forEach(queue, function(task) {
try {
task();
} catch(e) {
dump('exception in mockNextTick:', e, e.name, e.message, task);
}
});
}
}
}

beforeEach(function() {
args = null;
Expand Down Expand Up @@ -132,6 +153,91 @@ describe('injector', function() {
injector.invoke(['a', 123], {});
}).toThrow("[ng:areq] Argument 'fn' is not a function, got number");
});

it('should return a promise if an injected dependency is a promised service', function() {
providers('e', function() {return { then: function(){}};});
var returned = injector.invoke(['$q', 'e', fn]);
expect(typeof returned.then).toBe('function');
});

it('should call the function immediately if no injected dependencies are promised services', function() {
var testFnSpy = jasmine.createSpy('injectedPromise');
var returned = injector.invoke(['a', 'b', testFnSpy]);
expect(testFnSpy).toHaveBeenCalled();
});

it('should not call the function immediately if an injected dependency is a promised service', function() {
var testFnSpy = jasmine.createSpy('injectedPromise');
providers('e', function() {return { then: function(){}};});
var returned = injector.invoke(['$q', 'e', testFnSpy]);
expect(testFnSpy).not.toHaveBeenCalled();
});

it('should eventually call the function if an injected dependency is a promised service', function() {
var testFnSpy = jasmine.createSpy('injectedPromise');
var flag = false;
var asyncService = function($q){
return promise;
}

q = qFactory(mockNextTick.nextTick, noop);
deferred = q.defer()
promise = deferred.promise;
providers('$q', function(){return q});

runs(function(){
providers('e', asyncService);
var returned = injector.invoke(['e', testFnSpy]);
expect(testFnSpy).not.toHaveBeenCalled();
setTimeout(function(){
deferred.resolve();
mockNextTick.flush();
flag = true;
}, 50);
});

waitsFor(function(){
return flag;
}, "Error waiting for async-service injection", 200);

runs(function(){
expect(testFnSpy).toHaveBeenCalled();
});
});

it('should use the eventually-resolved Service as argument if an injected dependency is a promised service', function() {
var testFnSpy = jasmine.createSpy('injectedPromise');
var flag = false;
var asyncService = function($q){
return promise;
}
var testResolvedValue = '1234ABCD';

q = qFactory(mockNextTick.nextTick, noop);
deferred = q.defer()
promise = deferred.promise;
providers('$q', function(){return q});

runs(function(){
providers('e', asyncService);
var returned = injector.invoke(['e', testFnSpy]);
expect(testFnSpy).not.toHaveBeenCalled();
setTimeout(function(){
deferred.resolve(testResolvedValue);
mockNextTick.flush();
flag = true;
}, 50);
});

waitsFor(function(){
return flag;
}, "Error waiting for async-service injection", 200);

runs(function(){
expect(testFnSpy.mostRecentCall.args[0]).toEqual(testResolvedValue);
});
});

});


Expand Down