Vaadin grid lazy loading from external WEB API

General
1

Hi there:

I have a an external web API which returns a Page

@GetMapping(“/paged”)
public Page getpagedplotinformationview(Pageable pageable)
{
return _plotinformationview_repository.findAll(pageable);
}

Postman shows that the method works okay. Now…I have a frontend application that uses Vaadim grid to show the data. The unpaged data is retrieved without an issue, the problem is when I want to use the above method in the client side using the code below:

public List Pagedlist(Pageable pageable) {
return webClient.get()
.uri(uriBuilder → uriBuilder
.path(“api/paged”)
.build())
.accept(MediaType.APPLICATION_JSON)
.retrieve()
.toEntityList(plotinformationview.class)
.block().getBody();

The java class for the UI grid tries to populate the grid by calling the controller method as below:
grid.setItems(query → _plotinformationviewservices.Pagedlist(VaadinSpringDataHelpers.toSpringPageRequest(query)).stream())

I also tried
grid.setItemsPageable(query → _plotinformationviewservices.Pagedlist(query));

when I run the application, the debugger doesn’t throw any error and the browser Developer tools shows that the the WEB API is hit and returns a 200 HTTP response, however instead of appearing all the data in the vaadim grid the only thing that appears is a zero (0).
Obviously, I’m not doing something right but I don’t know what it is, the Pageable in the web api has default values in case that the pagesize and pagenumber parameters aren’t provided . I run the test in postman and yes…there is always data returned even if the query parameters aren’t provided by the frontend.
I read numerous articles about dataprovider and callbacks but I’m failing to understand as I haven’t come across with one simple example.

Any assistance will be gratly appreciated

Thanking you in advance.

Regards

Jose

2

Have you deubugged to see if the method returns data?

1 Like
3

Hi Simon:

Thanks for your assistance thus far. The response from the server is empty instead of receiving this

{
“key”: “1”,
“col0”: “11812”,
“col1”: “1 Omar Rd”,
“col2”: “85”,
“col3”: “Cornelius Noel Christopher”,
“col4”: “Lewis”,
“col5”: “”,
“col6”: “1976-12-24”
},

I receive

{
“key”: “1”,
“col0”: “0”,
“col1”: “”,
“col2”: “”,
“col3”: “”,
“col4”: “”,
“col5”: “”,
“col6”: “”
}

Meaning that although the server is hit ( HTTP 200), no data is return. As previously said, I’m not sure whether the way I’m calling the WEB REST API is the correct one
Any ideas?

4

So your Vaadin is fine and working. Your server sends garbage and the garbage is shown properly. So fix the server or fix the data the server is reading.