In Parse there is something called:
Parse.Cloud.beforeSave
I wonder if there is something to play the role of a:
Parse.Cloud.beforeRead
I need a way to control what is going to be returned to the user when a request is made to the DB.
In particular in certain circomstances, depending on information on the server, I want to force blank fields in the result of the DB request made by the user. Any standard way to do this?
There is no Parse.Cloud.beforeRead kind of function supported by Parse.
Instead, you can define a custom cloud function using
Parse.Cloud.define('readObjects', function(request, response) {...} );
that returns array of objects. This function will act as a wrapper over the Parse query.
Then, your client apps should be calling this cloud function to fetch objects rather than direct Parse.Query requests.
Related
So I have done a lot of research and could not find a proper answer. This might be a bit long post so sorry for that. I am making a backend API using golang. I am using gingonic for routing and api stuffs.
There are 2 part of the service. Application and user. When lets say createAccount endpoint is called from the other micro service, it need to pass the user information and application token in body. Each application is like micro service that is registered to this micro service that I am building and have a unique token. If the token they pass matches then I will get the id of that row and use that to create an entry in user table which will have the id associate with it.
Now for every API call to this micro service, it is important that they are sending the valid token and that row id is needed to do all sort of functionality like login user, edit user info and so on as the each user is connected with that app id by foreign key. Currently, I wrote a middleware and when any api call is made I get row id and save it to a global variable and then when necessary I am using it in any part of the codebase.
Lets say if 5 multiple API call is made, will that global variable information will be persisted or for each call its brand new value? If it is persisted then what can I do to achieve the brand new of Global variable for every API call or if there are better approach can you please recommend it?
A global variable is not the answer here. It will be overwritten by each request as you suspected. Instead, the typical way to handle this situation is to have a context object that is created within the scope of the HTTP Request and passed to each method that requires knowledge of that context.
One basic rule is to AVOID using the global variables, it is bad practices, you cannot manage the state and you are limited for testing and concurrency using.
In my mind come two basic solutions:
Use context for this. In your handler, add the value in context and propagate this context by all your service calls. It is also useful for tracing if you are working with microservices, then you also should take a look for this. And in the place where you need the value from your global variable, do simple call: ctx.Value(YOUR_KEY) Take a look at the end of the page, you shouldn't use string as the key to context values.
You can wrap your data in the struct with this variable value. For example:
type CreateReq struct {
Token string // value from global variable
User user
}
and use this Token in your services.
I want to perform an action based to the result of an asynchronous NGXS action.
In a Angular frontend app I'm using NGXS for state management. Some of the actions involve talking to a backend via REST calls. Those actions are implemented as asynchronous actions, with the reducer functions in my state classes returning an Observable.
What I'm looking for is a way to get hands on the result of the backend call, to be able to perform some action.
One use case I'm trying to implement is navigation to just created objects: Business objects are created in the frontend (Angular) app with a couple of domain properties. They get persisted in the backend, and as a result an ID for this object is created and returned to the frontend, and incorporated into the NGXS store. As a direct response to this, I'd like to navigate to a detail view for the new object. To do so, I need
(a) the information that the call has been returned successful, and
(b) the answer from the backend (the ID in this case).
Another slightly more complicated use case is the assignment of a number of tags to an business object. The tags are entities by themselfes, and have an ID each. In the UI, the user can either pick existing or add new tags. Either way, multiple tags can be added in a single step in the UI, which means I have to
call the backend for each new tag to create the ID
after all missing tags are created, update the business object with the list of tag IDs
In general, there are use cases in the frontend that depend on the result of a backend call, and there is no clean way to find this result in the store (although it's in there)
I know I can subscribe to the Observable returned from the store's dispatch method (as shown in asynchronous actions).
I also know about action handlers. In both cases I can attach code to the event of an action finished, but neither option enables me to get the result of the backend call. In the fist case, the Observable carries the whole store, while in the latter case I get the original Action, which is unfortunately missing the essential information (the ID).
The part you're missing here are selectors. Dispatching actions is not supposed to give you back a result. The only purpose of the Observable returned by store.dispatch() is to tell you when the action's handlers are done.
To get to the data returned by your calls to the backend, you have to patch the state inside your action handler. And then, outside of your state, you can access the data using store.select() or store.selectSnapshot() depending on what you need. Your state class should look somewhat like this (untested):
#State()
export class SampleState {
#Selector(SampleState)
sampleSelector(state) {
return state.sampleObject;
}
#Action(SampleAction)
sampleAction(ctx: StateContext<any>, action: sampleAction) {
return sampleBackendCall(/* ... */).pipe(
tap((result) => {
ctx.patchState({ sampleObject: result });
})
);
}
}
Now you can access this result where ever you need using the Store. For the use case of navigating to an element after its creation, you can combine a subscription to store.dispatch() with a store.selectSnapshot() like this:
store.dispatch(new SampleAction()).subscribe(() => {
navigateTo(store.selectSnapshot(SampleState.sampleSelector));
});
Note that in this easy case a selectSnapshot is perfectly fine, as we only want to get the value we just finished writing into the state. In most cases though, you will want to use store.select() or the #Select() decorator because they return Observables which enable you to also correctly display changes in your state.
That said, I'd like to add that if saving data inside the state is not necessary for you at all, then probably NGXS is the wrong library for you in the first place and you could as well just use an ordinary angular service directly returning the result of the backend call, like suggested in the comments.
I've read the docs and watched the Laracast. I'm still left wondering why you would use them?
I get that you can map different data to different names if your field names were to change but you want to keep a consistent public API. But surly you can just do the same on the model with the toArray() method and change the mappings there?
If I were to do:
return User::find(1);
I get a response like:
{"id":1,"name":"Ova Parker"}
If I do:
return new UserResource(User::find(1));
I get a response like:
{"data":{"id":1,"name":"Ova Parker"}}
Is there a significance in wrapping it with a data tag? I am just guessing but is this a standard JSON format for API's? Why would you not just do return User::find(1); instead of using an API resource, if this is under API routes then it'll return it as JSON anyway automatically.
You kind of answer the question by yourself. The idea behind API Resources or Transformers (like the ones from Fractal) is to hide the db field names from the client. With return User::find(1) you expose your whole db structure which might not a good idea security-wise and also bad for the release process. If you need to change a db field name, you have to change the API too. With Resources you have a mapping between your application and the consumer of you API.
It seems more work in the beginning, but once you started it, you won't wanna miss it anymore.
There is no toArray() method in PHP, which gets magically called like __toString(). You have to write you own and call it by yourself. Resources are built-in by Laravel and will be resolved automatically.
I've been trying to send a flag to save request. This save request is sent from different platforms so we seperated them with a flag. The problem is that it gives
Result: TypeError: Cannot read property '0' of undefined
when you send the request to table without the parameter. I did not want to add this parameter as a column in the table but it seems it automatically creates it when you successfully save the object. Is there a way to save the object without creating the flag column and seperate the save requests with and without the flag? Thank you in advance.
Parse.Cloud.beforeSave("MessageTest", function(request, response) {
if(!request.object.get("fromMessages")) {
..
..
}
else response.succcess();
});
If you try to save an object directly from your app, you cannot remove the field from your request in beforeSave trigger. A better approach is to save your object via a Cloud function instead. Send in your object alongside of your platform flag to a cloud function, then construct a MessageTest object from the parameters (obviously ignoring your platform flag) and then save it from there.
I'm making a pretty standard AJAXy (well, no XML actually) web page. The browser makes a bunch of API queries that return JSON to run the site. The problem is, I need to add to the API interface each time the page needs to do something new. The new API interface is usually little more than a database query followed by mapping the returned objects to JSON.
What I'd like to do is to get rid of all that server-side duplication and just have the page make database requests itself (using the model interface), but in a way that is safe (i.e. just read only ones). I think this would amount to an interface for constructing Q objects using JSON or something like that, and then send that up to the server, run the query, and return the results. Before I go making my own half-broken architecture for this, I'm wondering if this has already been done well. Also, is this even the best way to go about eliminating this duplication?
Thanks
Search multiple fields of django model without 3rd party app
Django SQL OR via filter() & Q(): Dynamic?
Generate a django queryset based on dict keys
Just replace with operator.and_ where appropriate.