Prevent unnecessary query when no results are found by the count query

Author: darrachequesne

src/main/java/org/springframework/data/jpa/datatables/mapping/DataTablesOutput.java

@@ -19,14 +19,14 @@ public class DataTablesOutput<T> {
  * Total records, before filtering (i.e. the total number of records in the database)
  */
  @JsonView(View.class)
- private Long recordsTotal;
+ private Long recordsTotal = 0L;
 
  /**
  * Total records, after filtering (i.e. the total number of records after filtering has been
  * applied - not just the number of records being returned for this page of data).
  */
  @JsonView(View.class)
- private Long recordsFiltered;
+ private Long recordsFiltered = 0L;
 
  /**
  * The data to be displayed in the table. This is an array of data source objects, one for each

src/main/java/org/springframework/data/jpa/datatables/qrepository/QDataTablesRepositoryImpl.java

@@ -62,8 +62,11 @@ public DataTablesOutput<T> findAll(DataTablesInput input, Predicate additionalPr
  DataTablesOutput<T> output = new DataTablesOutput<T>();
  output.setDraw(input.getDraw());
  try {
- output
- .setRecordsTotal(preFilteringPredicate == null ? count() : count(preFilteringPredicate));
+ long recordsTotal = preFilteringPredicate == null ? count() : count(preFilteringPredicate);
+ if (recordsTotal == 0) {
+ return output;
+ }
+ output.setRecordsTotal(recordsTotal);
 
  Page<T> data = findAll(new BooleanBuilder().and(getPredicate(this.builder, input))
  .and(additionalPredicate).and(preFilteringPredicate).getValue(), getPageable(input));

src/main/java/org/springframework/data/jpa/datatables/repository/DataTablesRepositoryImpl.java

@@ -47,8 +47,12 @@ public DataTablesOutput<T> findAll(DataTablesInput input,
  output.setDraw(input.getDraw());
 
  try {
- output.setRecordsTotal(
- preFilteringSpecification == null ? count() : count(preFilteringSpecification));
+ long recordsTotal =
+ preFilteringSpecification == null ? count() : count(preFilteringSpecification);
+ if (recordsTotal == 0) {
+ return output;
+ }
+ output.setRecordsTotal(recordsTotal);
 
  Page<T> data = findAll(Specifications.where(getSpecification(getDomainClass(), input))
  .and(additionalSpecification).and(preFilteringSpecification), getPageable(input));