Merge pull request #873 from alphagov/pp_6768_next_link

PP-6768 Optimise next_link generation
alphagov · Aug 5, 2020 · 22deb19 · 22deb19
2 parents ec4c424 + cf36b81
commit 22deb19
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Showing 3 changed files with 30 additions and 4 deletions.
diff --git a/src/main/java/uk/gov/pay/ledger/transaction/service/TransactionService.java b/src/main/java/uk/gov/pay/ledger/transaction/service/TransactionService.java
@@ -125,7 +125,10 @@ public List<TransactionEntity> searchTransactionAfter(TransactionSearchParams se
     private TransactionSearchResponse buildTransactionSearchResponse(TransactionSearchParams searchParams, UriInfo uriInfo, List<Transaction> transactionList, Long totalCount) {
         Long total = Optional.ofNullable(totalCount).orElse(0L);
         PaginationBuilder paginationBuilder = new PaginationBuilder(searchParams, uriInfo);
-        paginationBuilder = paginationBuilder.withTotalCount(total).buildResponse();
+        paginationBuilder = paginationBuilder
+                .withTotalCount(total)
+                .withCount((long) transactionList.size())
+                .buildResponse();
 
         List<TransactionView> transactionViewList = mapToTransactionViewList(transactionList, searchParams.getStatusVersion());
 

diff --git a/src/main/java/uk/gov/pay/ledger/util/pagination/PaginationBuilder.java b/src/main/java/uk/gov/pay/ledger/util/pagination/PaginationBuilder.java
@@ -7,6 +7,7 @@
 
 import javax.ws.rs.core.UriInfo;
 import java.net.URI;
+import java.util.Objects;
 
 import static com.fasterxml.jackson.annotation.JsonInclude.Include;
 
@@ -24,6 +25,8 @@ public class PaginationBuilder {
     @JsonIgnore
     private Long totalCount;
     @JsonIgnore
+    private Long count;
+    @JsonIgnore
     private Long selfPageNum;
     @JsonProperty(SELF_LINK)
     private PaginationLink selfLink;
@@ -47,6 +50,11 @@ public PaginationBuilder withTotalCount(Long total) {
         return this;
     }
 
+    public PaginationBuilder withCount(Long count) {
+        this.count = count;
+        return this;
+    }
+
     public PaginationBuilder buildResponse() {
 
         if (searchParams.limitTotal()) {
@@ -84,7 +92,9 @@ private void buildLinksForLimitTotal() {
         selfLink = PaginationLink.ofValue(uriWithParams(searchParams.buildQueryParamString(searchParams.getPageNumber())));
         firstLink = PaginationLink.ofValue(uriWithParams(searchParams.buildQueryParamString(1L)));
 
-        nextLink = PaginationLink.ofValue(uriWithParams(searchParams.buildQueryParamString(selfPageNum + 1)));
+        if (Objects.equals(count, searchParams.getDisplaySize())) {
+            nextLink = PaginationLink.ofValue(uriWithParams(searchParams.buildQueryParamString(selfPageNum + 1)));
+        }
 
         if (selfPageNum == 1L) {
             prevLink = null;

diff --git a/src/test/java/uk/gov/pay/ledger/util/pagination/PaginationBuilderTest.java b/src/test/java/uk/gov/pay/ledger/util/pagination/PaginationBuilderTest.java
@@ -102,7 +102,8 @@ public void shouldBuildLinksCorrectly_whenLimitTotalParamIsSetAndFirstPageIsAcce
         transactionSearchParams.setDisplaySize(10L);
         transactionSearchParams.setLimitTotal(true);
         PaginationBuilder builder = new PaginationBuilder(transactionSearchParams, mockedUriInfo)
-                .withTotalCount(120L);
+                .withTotalCount(120L)
+                .withCount(10L);
         builder = builder.buildResponse();
         assertThat(builder.getFirstLink().getHref().contains("page=1&display_size=10"), is(true));
         assertThat(builder.getLastLink(), is(nullValue()));
@@ -117,12 +118,24 @@ public void shouldShowAllLinksCorrectly_whenLimitTotalParamIsSetAndMultiplePages
         transactionSearchParams.setDisplaySize(10L);
         transactionSearchParams.setLimitTotal(true);
         PaginationBuilder builder = new PaginationBuilder(transactionSearchParams, mockedUriInfo)
-                .withTotalCount(120L);
+                .withTotalCount(120L)
+                .withCount(10L);
         builder = builder.buildResponse();
         assertThat(builder.getFirstLink().getHref().contains("page=1&display_size=10"), is(true));
         assertThat(builder.getLastLink(), is(nullValue()));
         assertThat(builder.getPrevLink().getHref().contains("page=2&display_size=10"), is(true));
         assertThat(builder.getNextLink().getHref().contains("page=4&display_size=10"), is(true));
         assertThat(builder.getSelfLink().getHref().contains("page=3&display_size=10"), is(true));
     }
+
+    @Test
+    public void shouldNotGenerateNextLink_whenLimitTotalIsSetAndCountIsLessThanPageSize() {
+        transactionSearchParams.setDisplaySize(10L);
+        transactionSearchParams.setLimitTotal(true);
+        PaginationBuilder builder = new PaginationBuilder(transactionSearchParams, mockedUriInfo)
+                .withTotalCount(120L)
+                .withCount(9L);
+        builder = builder.buildResponse();
+        assertThat(builder.getNextLink(), is(nullValue()));
+    }
 }