Passing List of Integers to GET REST API

问题:

I wanted to fetch the List of Entities from database at Front end. So I have written POST REST HTTP call in Spring MVC.

But I read the HTTP documentation which says whenever you have to retrieve data from database prefer GET call. So, Is it there is any I can replace the POST call to GET call from angular JS and pass list of Integers. But, GET HTTP has many drawbacks like : the length of URL is limited.Considering the case where we have to fetch 1000 entities from database.

Please suggest me the possible way to get the entities or write GET REST API in Spring MVC for list of integers(refers to ID's of Entities).

For Example : Consider there are 100 books in book table, But I want only few books, say id : 5,65,42,10,53,87,34,23. Thats why I am passing this List of Id's in a List of Integer in POST call.

Currently stuck how to convert this to GET call. In Short, how to pass List of Integers through GET REST call.

回答1:

I prefer a variant through HTTP path variable for your problem, because of in REST ideology a resource ID is passed after a resource name 'http://../resource/id' and HTTP parameters are used for filtering.

Through HTTP parameters

If you need to pass your ids through HTTP parameters, see an axample below:

Here is your Spring MVC controller method:

@RequestMapping(value = "/books", params = "ids", method = RequestMethod.GET)
@ResponseBody
Object getBooksById_params(@RequestParam List<Integer> ids) {
    return "ids=" + ids.toString();
}

And you can make a call using next variants:

1. http://server:port/ctx/books?ids=5,65,42
2. http://server:port/ctx/books?ids=5&ids=65&ids=42

Also take a look this discussion: https://stackoverflow.com/a/9547490/1881761

---

Through HTTP path variables

Also you can pass your ids through path variable, see an example below:

@RequestMapping(value = "/books/{ids}", method = RequestMethod.GET)
@ResponseBody
Object getBooksById_pathVariable(@PathVariable List<Integer> ids) {
    return "ids=" + ids.toString();
}

And your call will be look like this: http://server:port/ctx/books/5,65,42

---

回答2:

Pros of GET HTTP call : It is always used for retrieval of Data.(From this perspective : we should implemented for each and every and retrieval)

Through HTTP parameters

If you need to pass your ids through HTTP parameters, see an axample below:

Here is your Spring MVC controller method:

@RequestMapping(value = "/book", params = "ids", method = RequestMethod.GET)
@ResponseBody
Object getBooksById_params(@RequestParam List<Integer> ids) {
return "ids=" + ids.toString();
}    

It works fine but for exceptional case : say URI is above 2048 characters. It means there are many Id's in the list(eg : 1000)

then its throws an exception : return 414 (Request-URI Too Long)

which is http://www.checkupdown.com/status/E414.html

After some research MY UNDERSTANDING is : The HTTP protocol does not place any a priori limit on the lenght of a URI. Servers MUST be able to handle the URI of any resources they serve, and SHOULD be able to handle URIs of unbounded length if they provide GET-based forms that could generate such URIs. A server SHOULD return 414(Request_URI Too Long) status if a URI is longer than the server can handle.

I have also gone through sites like to get the GET URI length :

• http://www.w3.org/Protocols/rfc2616/rfc2616-sec3.html#sec3.2.1

So conclusion, is stick to POST call when there can be variable URI length at runtime for not getting such exception[return 414 (Request-URI Too Long)]

回答3:

Alternatively, to allow for complex queries you'll need to give the query its own rest language. So to create a query you POST to /library/query then you edit it with things like POST /library/query/12345 with data {id:34} and then you execute the query with GET /library/books?query=12345

回答4:

If you want to read entities from your API you have to use a GET call.

The better way to get them all is to use a query params as filter.

REST DESIGN cannot retrieve more than one entity each time by id.

An example:

GET /library/books/58731 -> returns only one book identified by 58731

GET /library/books?numPages>70 returns all the books with more than 70 pages

I think that If you need to retrieve a lot of books because they have some logic that all matches, try to put it as a queryString.

Another example:

GET /library/books?stored>20150101 returns all the books added to library on 2015

If you give us more information about the collection and the requirements we will answer more directly.