i have an action which will invoke a service (not database)to get some data for display,and i want to do paging on these data.however,every time a second page is clicked,it will invoke this action and of course invoke the service again,actually when i click the first page link,it already generate the whole data including what the second page needs. i just want to invoke the service once and get all the data,and later when paging,i don't need to invoke the service again,how can i deal with that?hope someone could give me a hint~
There are several ways to address this. If it's practical and a limited amount of data, it's ok to return the entire data set in the first request.
If that's your case I would consider returning a pure JSON object when you load the page initially. You can then deserialize this into a JS object variable on the web page that you can perform your paging operations against. This is an example of client side paging where all the data exists client side.
Another approach is to do Ajax based paging where you request the data for the next page as needed. I would still recommend returning JSON in this scenario as well.
The two approaches differ in that the first one returns all the data upfront, whereas the second one only returns what you need to render any given page.
Related
VueJS + Quasar + Pinia + Axios
Single page application
I have an entity called user with 4 endpoints associated:
GET /users
POST /user
PUT /user/{id}
DELETE /user/{id}
When I load my page I call the GET and I save the response slice of users inside a store (userStore)
Post and Put returns the created/updated user in the body of the response
Is it a good practice to manually update the slice of users in the store after calling one of these endpoints, or is better to call the GET immediatly after ?
If you own the API or can be sure about the behavior of what PUT/POST methods return, you can use local state manipulation. Those endpoints should return the same value as what the GET endpoint returns inside. Otherwise, you might end up with incomplete or wrong data on the local state.
By mutating the state locally without making an extra GET request, the user can immediately see the change in the browser. It will also be kinder to your server and the user's data usage.
However, if creating the resource(user, in this case) was a really common operation accessible by lots of users, then calling the GET endpoint to return a slice would be better since it would have more chance to include the new ones that are created by other users. But, in that case, listening to real-time events(i.e. using WebSockets) would be even better to ensure everyone gets accurate and new data in real-time.
I am currently working on a REST API for a project. In the process I should search for events. I would like to make an endpoint for searching events in a period. That is, specify two parameters with from - to.
For the search you normally take a GET operation. My question is now it makes sense to specify two parameters in the path or should I rather fall back to a POST operation for something like that.
Example for the path /Events{From}{To}
Is this even feasible with multiple parameters?
If you are not making a change on the resource, you should use GET operation.
More detailed explanation:
If you were writing a plain old RPC API call, they could technically interchangeable as long as the processing server side were no different between both calls. However, in order for the call to be RESTful, calling the endpoint via the GET method should have a distinct functionality (which is to get resource(s)) from the POST method (which is to create new resources).
GET request with multiple parameters: /events?param1=value1¶m2=value2
GET request with an array as parameter: /events?param=value1,value2,value3
We(producer for the API) have an endpoint
/users/:{id}/name
which is used to retrieve name for the user 'id'
Now as a consumer I want to display the list of names for users like:
user1: id1, name1
uder2: id2, name2
where I have the ids in input.
In such a case should I make 2(here the list is dependent on UI pagination example 50) separate calls to the API to fetch information or else create/ask the producer to create a bulk endpoint like:
POST /users/name
body: { ids: []}
If later, then am I not loosing the REST principle here to fetch information using POST but not GET? If former, then I am not putting too much network overhead in the system?
Also since this seems to be a very common usecase, if we choose the POST method is there really a need of the GET endpoint since the POST endpoint can handle a single user as well?
Which approach should be chosen?
A GET API call should be used for fetching data. Since browser knows GET calls are idempotent, it can handle some situations on its own, like make another call if previous fails.
Since REST calls are lightweight, we tend to overuse API call repeatedly. In your case, since you want all name v/s id mapping at once, one call is sufficient. Or have a Aggregator endpoint in backend API gateway to reduce network traffic and make repeated calls nearer to actual service.
Keeping GET /users/:{id}/name , is also not a bad idea alongside this. It helps to abstract business functionality. A particular scenario can only allow single fetch.
Also using GET /users/name with pagination and returning list of names is complex for single use so keeping both are fine.
Can any one suggests the best way to page through an API in Mule 4? The examples I saw used a choice with a flow reference to call the flow again in a loop. This API doesn't return the total number of records or pages so need to loop through each page until it returns an empty payload.
But if I call the same flow recursively, its throwing too many child context error.
What is the ideal way to handle this scenario?
I faced same kind of scenario recently. I have done a recursive call using another flow to call the parent flow. If you use a flow reference from the same flow it will not allow you to do so.
In the child flow, I have incremented the next start index as well.
If you are looking for paging from the API level, you can accept the start index and the Page size as the two parameters. This call can go until the number of records < page size OR the API returns 0 records.
I have a subroutine in my Controller
<HttpPost>
Sub Index(Id, varLotsOfData)
'Point B.
'By the time it gets here - all the data has been accepted by server.
What I would like to do it capture the Id of the inbound POST and mark, for example, a database record to say "Id xx is receiving data"
The POST receive can take a long time as there is lots of data.
When execution gets to point B I can mark the record "All data received".
Where can I place this type of "pre-POST completed" code?
I should add - we are receiving the POST data from clients that we do not control - that is, it is most likely a client's server sending the data - not a webbrowser client that we have served up from our webserver.
UPDATE: This is looking more complex than I had imagined.
I'm thinking that a possible solution would be to inspect the worker processes in IIS programatically. Via the IIS Manager you can do this for example - How to use IIS Manager to get Worker Processes (w3wp.exe) details information ?
From your description, you want to display on the client page that the method is executing and you can show also a loading gif, and when the execution completed, you will show a message to the user that the execution is completed.
The answer is simply: use SignalR
here you can find some references
Getting started with signalR 1.x and Mvc4
Creating your first SignalR hub MVC project
Hope this will help you
If I understand your goal correctly, it sounds like HttpRequest.GetBufferlessInputStream might be worth a look. It allows you to begin acting on incoming post data immediately and in "pieces" rather than waiting until the entire post has been received.
An excerpt from Microsoft's documentation:
...provides an alternative to using the InputStream propertywhich waits until the whole request has been received. In contrast, the GetBufferlessInputStream method returns the Stream object immediately. You can use the method to begin processing the entity body before the complete contents of the body have been received and asynchronously read the request entity in chunks. This method can be useful if the request is uploading a large file and you want to begin accessing the file contents before the upload is finished.
So you could grab the beginning of the post, and provided your client-facing page sends the ID towards the beginning of its transmission, you may be able to pull that out. Of course, this would be reading raw byte data which would need to be decoded so you could grab the inbound post's ID. There's also a buffered one that will allow the stream to be read in pieces but will also build a complete request object for processing once it has been completely received.
Create a custom action filter,
Action Filters for executing filtering logic either before or after an action method is called. Action Filters are custom attributes that provide declarative means to add pre-action and post-action behavior to the controller's action methods.
Specifically you'll want to look at the
OnActionExecuted – This method is called after a controller action is executed.
Here are a couple of links:
http://www.infragistics.com/community/blogs/dhananjay_kumar/archive/2016/03/04/how-to-create-a-custom-action-filter-in-asp-net-mvc.aspx
http://www.asp.net/mvc/overview/older-versions-1/controllers-and-routing/understanding-action-filters-vb
Here is a lab, but I think it's C#
http://www.asp.net/mvc/overview/older-versions/hands-on-labs/aspnet-mvc-4-custom-action-filters