Package tech.jhipster.service

Class QueryService<ENTITY>

java.lang.Object
tech.jhipster.service.QueryService<ENTITY>
Type Parameters:
ENTITY - the type of the entity which is queried.
@Transactional(readOnly=true) public abstract class QueryService<ENTITY> extends Object
Base service for constructing and executing complex queries.

  • Constructor Summary

    Constructors
    Constructor
    Description
    QueryService()
     

  • Method Summary

    Modifier and Type
    Method
    Description
    protected <X extends Comparable<? super X>>
    org.springframework.data.jpa.domain.Specification<ENTITY>
    buildRangeSpecification(RangeFilter<X> filter, jakarta.persistence.metamodel.SingularAttribute<? super ENTITY,X> field)
    Helper function to return a specification for filtering on a single Comparable, where equality, less than, greater than and less-than-or-equal-to and greater-than-or-equal-to and null/non-null conditions are supported.
    protected <OTHER, X> org.springframework.data.jpa.domain.Specification<ENTITY>
    buildReferringEntitySpecification(Filter<X> filter, jakarta.persistence.metamodel.SetAttribute<ENTITY,OTHER> reference, jakarta.persistence.metamodel.SingularAttribute<OTHER,X> valueField)
    Helper function to return a specification for filtering on one-to-many or many-to-many reference.
    protected <OTHER, X> org.springframework.data.jpa.domain.Specification<ENTITY>
    buildReferringEntitySpecification(Filter<X> filter, jakarta.persistence.metamodel.SingularAttribute<? super ENTITY,OTHER> reference, jakarta.persistence.metamodel.SingularAttribute<? super OTHER,X> valueField)
    Helper function to return a specification for filtering on one-to-one or many-to-one reference.
    protected <OTHER, MISC, X>
    org.springframework.data.jpa.domain.Specification<ENTITY>
    buildReferringEntitySpecification(Filter<X> filter, Function<jakarta.persistence.criteria.Root<ENTITY>,jakarta.persistence.criteria.SetJoin<MISC,OTHER>> functionToEntity, Function<jakarta.persistence.criteria.SetJoin<MISC,OTHER>,jakarta.persistence.criteria.Expression<X>> entityToColumn)
    Helper function to return a specification for filtering on one-to-many or many-to-many reference.Usage:
    protected <OTHER, X extends Comparable<? super X>>
    org.springframework.data.jpa.domain.Specification<ENTITY>
    buildReferringEntitySpecification(RangeFilter<X> filter, jakarta.persistence.metamodel.SetAttribute<ENTITY,OTHER> reference, jakarta.persistence.metamodel.SingularAttribute<OTHER,X> valueField)
    Helper function to return a specification for filtering on one-to-many or many-to-many reference.Where equality, less than, greater than and less-than-or-equal-to and greater-than-or-equal-to and null/non-null conditions are supported.
    protected <OTHER, MISC, X extends Comparable<? super X>>
    org.springframework.data.jpa.domain.Specification<ENTITY>
    buildReferringEntitySpecification(RangeFilter<X> filter, Function<jakarta.persistence.criteria.Root<ENTITY>,jakarta.persistence.criteria.SetJoin<MISC,OTHER>> functionToEntity, Function<jakarta.persistence.criteria.SetJoin<MISC,OTHER>,jakarta.persistence.criteria.Expression<X>> entityToColumn)
    Helper function to return a specification for filtering on one-to-many or many-to-many reference.Where equality, less than, greater than and less-than-or-equal-to and greater-than-or-equal-to and null/non-null conditions are supported.
    protected <X> org.springframework.data.jpa.domain.Specification<ENTITY>
    buildSpecification(Filter<X> filter, jakarta.persistence.metamodel.SingularAttribute<? super ENTITY,X> field)
    Helper function to return a specification for filtering on a single field, where equality, and null/non-null conditions are supported.
    protected <X> org.springframework.data.jpa.domain.Specification<ENTITY>
    buildSpecification(Filter<X> filter, Function<jakarta.persistence.criteria.Root<ENTITY>,jakarta.persistence.criteria.Expression<X>> metaclassFunction)
    Helper function to return a specification for filtering on a single field, where equality, and null/non-null conditions are supported.
    protected <X extends Comparable<? super X>>
    org.springframework.data.jpa.domain.Specification<ENTITY>
    buildSpecification(RangeFilter<X> filter, Function<jakarta.persistence.criteria.Root<ENTITY>,jakarta.persistence.criteria.Expression<X>> metaclassFunction)
    Helper function to return a specification for filtering on a single Comparable, where equality, less than, greater than and less-than-or-equal-to and greater-than-or-equal-to and null/non-null conditions are supported.
    protected org.springframework.data.jpa.domain.Specification<ENTITY>
    buildSpecification(StringFilter filter, Function<jakarta.persistence.criteria.Root<ENTITY>,jakarta.persistence.criteria.Expression<String>> metaclassFunction)
    Helper function to return a specification for filtering on a String field, where equality, containment, and null/non-null conditions are supported.
    protected org.springframework.data.jpa.domain.Specification<ENTITY>
    buildStringSpecification(StringFilter filter, jakarta.persistence.metamodel.SingularAttribute<? super ENTITY,String> field)
    Helper function to return a specification for filtering on a String field, where equality, containment, and null/non-null conditions are supported.
    protected <X> org.springframework.data.jpa.domain.Specification<ENTITY>
    byFieldEmptiness(Function<jakarta.persistence.criteria.Root<ENTITY>,jakarta.persistence.criteria.Expression<Set<X>>> metaclassFunction, boolean specified)
    byFieldEmptiness.
    protected <X> org.springframework.data.jpa.domain.Specification<ENTITY>
    byFieldSpecified(Function<jakarta.persistence.criteria.Root<ENTITY>,jakarta.persistence.criteria.Expression<X>> metaclassFunction, boolean specified)
    byFieldSpecified.
    protected org.springframework.data.jpa.domain.Specification<ENTITY>
    distinct(boolean distinct)
    distinct.
    protected org.springframework.data.jpa.domain.Specification<ENTITY>
    doesNotContainSpecification(Function<jakarta.persistence.criteria.Root<ENTITY>,jakarta.persistence.criteria.Expression<String>> metaclassFunction, String value)
    doesNotContainSpecification.
    protected <X> org.springframework.data.jpa.domain.Specification<ENTITY>
    equalsSpecification(Function<jakarta.persistence.criteria.Root<ENTITY>,jakarta.persistence.criteria.Expression<X>> metaclassFunction, X value)
    Generic method, which based on a Root<ENTITY> returns an Expression which type is the same as the given 'value' type.
    protected <X extends Comparable<? super X>>
    org.springframework.data.jpa.domain.Specification<ENTITY>
    greaterThan(Function<jakarta.persistence.criteria.Root<ENTITY>,jakarta.persistence.criteria.Expression<X>> metaclassFunction, X value)
    greaterThan.
    protected <X extends Comparable<? super X>>
    org.springframework.data.jpa.domain.Specification<ENTITY>
    greaterThanOrEqualTo(Function<jakarta.persistence.criteria.Root<ENTITY>,jakarta.persistence.criteria.Expression<X>> metaclassFunction, X value)
    greaterThanOrEqualTo.
    protected <X extends Comparable<? super X>>
    org.springframework.data.jpa.domain.Specification<ENTITY>
    lessThan(Function<jakarta.persistence.criteria.Root<ENTITY>,jakarta.persistence.criteria.Expression<X>> metaclassFunction, X value)
    lessThan.
    protected <X extends Comparable<? super X>>
    org.springframework.data.jpa.domain.Specification<ENTITY>
    lessThanOrEqualTo(Function<jakarta.persistence.criteria.Root<ENTITY>,jakarta.persistence.criteria.Expression<X>> metaclassFunction, X value)
    lessThanOrEqualTo.
    protected org.springframework.data.jpa.domain.Specification<ENTITY>
    likeUpperSpecification(Function<jakarta.persistence.criteria.Root<ENTITY>,jakarta.persistence.criteria.Expression<String>> metaclassFunction, String value)
    likeUpperSpecification.
    protected <X> org.springframework.data.jpa.domain.Specification<ENTITY>
    notEqualsSpecification(Function<jakarta.persistence.criteria.Root<ENTITY>,jakarta.persistence.criteria.Expression<X>> metaclassFunction, X value)
    Generic method, which based on a Root<ENTITY> returns an Expression which type is the same as the given 'value' type.
    protected <X> org.springframework.data.jpa.domain.Specification<ENTITY>
    valueIn(Function<jakarta.persistence.criteria.Root<ENTITY>,jakarta.persistence.criteria.Expression<X>> metaclassFunction, Collection<X> values)
    valueIn.
    protected <X> org.springframework.data.jpa.domain.Specification<ENTITY>
    valueNotIn(Function<jakarta.persistence.criteria.Root<ENTITY>,jakarta.persistence.criteria.Expression<X>> metaclassFunction, Collection<X> values)
    valueNotIn.
    protected String
    wrapLikeQuery(String txt)
    wrapLikeQuery.

    Methods inherited from class java.lang.Object

    clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

  • Constructor Details

    • QueryService

      public QueryService()

  • Method Details

    • buildSpecification

      protected <X> org.springframework.data.jpa.domain.Specification<ENTITY> buildSpecification(Filter<X> filter, jakarta.persistence.metamodel.SingularAttribute<? super ENTITY,X> field)
      Helper function to return a specification for filtering on a single field, where equality, and null/non-null conditions are supported.
      Type Parameters:
      X - The type of the attribute which is filtered.
      Parameters:
      filter - the individual attribute filter coming from the frontend.
      field - the JPA static metamodel representing the field.
      Returns:
      a Specification

    • buildSpecification

      protected <X> org.springframework.data.jpa.domain.Specification<ENTITY> buildSpecification(Filter<X> filter, Function<jakarta.persistence.criteria.Root<ENTITY>,jakarta.persistence.criteria.Expression<X>> metaclassFunction)
      Helper function to return a specification for filtering on a single field, where equality, and null/non-null conditions are supported.
      Type Parameters:
      X - The type of the attribute which is filtered.
      Parameters:
      filter - the individual attribute filter coming from the frontend.
      metaclassFunction - the function, which navigates from the current entity to a column, for which the filter applies.
      Returns:
      a Specification

    • buildStringSpecification

      protected org.springframework.data.jpa.domain.Specification<ENTITY> buildStringSpecification(StringFilter filter, jakarta.persistence.metamodel.SingularAttribute<? super ENTITY,String> field)
      Helper function to return a specification for filtering on a String field, where equality, containment, and null/non-null conditions are supported.
      Parameters:
      filter - the individual attribute filter coming from the frontend.
      field - the JPA static metamodel representing the field.
      Returns:
      a Specification

    • buildSpecification

      protected org.springframework.data.jpa.domain.Specification<ENTITY> buildSpecification(StringFilter filter, Function<jakarta.persistence.criteria.Root<ENTITY>,jakarta.persistence.criteria.Expression<String>> metaclassFunction)
      Helper function to return a specification for filtering on a String field, where equality, containment, and null/non-null conditions are supported.
      Parameters:
      filter - the individual attribute filter coming from the frontend.
      metaclassFunction - lambda, which based on a Root<ENTITY> returns Expression - basicaly picks a column
      Returns:
      a Specification

    • buildRangeSpecification

      protected <X extends Comparable<? super X>> org.springframework.data.jpa.domain.Specification<ENTITY> buildRangeSpecification(RangeFilter<X> filter, jakarta.persistence.metamodel.SingularAttribute<? super ENTITY,X> field)
      Helper function to return a specification for filtering on a single Comparable, where equality, less than, greater than and less-than-or-equal-to and greater-than-or-equal-to and null/non-null conditions are supported.
      Type Parameters:
      X - The type of the attribute which is filtered.
      Parameters:
      filter - the individual attribute filter coming from the frontend.
      field - the JPA static metamodel representing the field.
      Returns:
      a Specification

    • buildSpecification

      protected <X extends Comparable<? super X>> org.springframework.data.jpa.domain.Specification<ENTITY> buildSpecification(RangeFilter<X> filter, Function<jakarta.persistence.criteria.Root<ENTITY>,jakarta.persistence.criteria.Expression<X>> metaclassFunction)
      Helper function to return a specification for filtering on a single Comparable, where equality, less than, greater than and less-than-or-equal-to and greater-than-or-equal-to and null/non-null conditions are supported.
      Type Parameters:
      X - The type of the attribute which is filtered.
      Parameters:
      filter - the individual attribute filter coming from the frontend.
      metaclassFunction - lambda, which based on a Root<ENTITY> returns Expression - basicaly picks a column
      Returns:
      a Specification

    • buildReferringEntitySpecification

      protected <OTHER, X> org.springframework.data.jpa.domain.Specification<ENTITY> buildReferringEntitySpecification(Filter<X> filter, jakarta.persistence.metamodel.SingularAttribute<? super ENTITY,OTHER> reference, jakarta.persistence.metamodel.SingularAttribute<? super OTHER,X> valueField)
      Helper function to return a specification for filtering on one-to-one or many-to-one reference. Usage: 
         Specification<Employee> specByProjectId = buildReferringEntitySpecification(criteria.getProjectId(),
 Employee_.project, Project_.id);
   Specification<Employee> specByProjectName = buildReferringEntitySpecification(criteria.getProjectName(),
 Employee_.project, Project_.name);
      Type Parameters:
      OTHER - The type of the referenced entity.
      X - The type of the attribute which is filtered.
      Parameters:
      filter - the filter object which contains a value, which needs to match or a flag if nullness is checked.
      reference - the attribute of the static metamodel for the referring entity.
      valueField - the attribute of the static metamodel of the referred entity, where the equality should be checked.
      Returns:
      a Specification

    • buildReferringEntitySpecification

      protected <OTHER, X> org.springframework.data.jpa.domain.Specification<ENTITY> buildReferringEntitySpecification(Filter<X> filter, jakarta.persistence.metamodel.SetAttribute<ENTITY,OTHER> reference, jakarta.persistence.metamodel.SingularAttribute<OTHER,X> valueField)
      Helper function to return a specification for filtering on one-to-many or many-to-many reference. Usage: 
         Specification<Employee> specByEmployeeId = buildReferringEntitySpecification(criteria.getEmployeId(),
 Project_.employees, Employee_.id);
   Specification<Employee> specByEmployeeName = buildReferringEntitySpecification(criteria.getEmployeName(),
 Project_.project, Project_.name);
      Type Parameters:
      OTHER - The type of the referenced entity.
      X - The type of the attribute which is filtered.
      Parameters:
      filter - the filter object which contains a value, which needs to match or a flag if emptiness is checked.
      reference - the attribute of the static metamodel for the referring entity.
      valueField - the attribute of the static metamodel of the referred entity, where the equality should be checked.
      Returns:
      a Specification

    • buildReferringEntitySpecification

      protected <OTHER, MISC, X> org.springframework.data.jpa.domain.Specification<ENTITY> buildReferringEntitySpecification(Filter<X> filter, Function<jakarta.persistence.criteria.Root<ENTITY>,jakarta.persistence.criteria.SetJoin<MISC,OTHER>> functionToEntity, Function<jakarta.persistence.criteria.SetJoin<MISC,OTHER>,jakarta.persistence.criteria.Expression<X>> entityToColumn)
      Helper function to return a specification for filtering on one-to-many or many-to-many reference.Usage:
         Specification<Employee> specByEmployeeId = buildReferringEntitySpecification(
          criteria.getEmployeId(),
          root -> root.get(Project_.company).join(Company_.employees),
          entity -> entity.get(Employee_.id));
   Specification<Employee> specByProjectName = buildReferringEntitySpecification(
          criteria.getProjectName(),
          root -> root.get(Project_.project)
          entity -> entity.get(Project_.name));
      Type Parameters:
      OTHER - The type of the referenced entity.
      MISC - The type of the entity which is the last before the OTHER in the chain.
      X - The type of the attribute which is filtered.
      Parameters:
      filter - the filter object which contains a value, which needs to match or a flag if emptiness is checked.
      functionToEntity - the function, which joins he current entity to the entity set, on which the filtering is applied.
      entityToColumn - the function, which of the static metamodel of the referred entity, where the equality should be checked.
      Returns:
      a Specification

    • buildReferringEntitySpecification

      protected <OTHER, X extends Comparable<? super X>> org.springframework.data.jpa.domain.Specification<ENTITY> buildReferringEntitySpecification(RangeFilter<X> filter, jakarta.persistence.metamodel.SetAttribute<ENTITY,OTHER> reference, jakarta.persistence.metamodel.SingularAttribute<OTHER,X> valueField)
      Helper function to return a specification for filtering on one-to-many or many-to-many reference.Where equality, less than, greater than and less-than-or-equal-to and greater-than-or-equal-to and null/non-null conditions are supported. Usage: 
         Specification<Employee> specByEmployeeId = buildReferringEntitySpecification(criteria.getEmployeId(),
 Project_.employees, Employee_.id);
   Specification<Employee> specByEmployeeName = buildReferringEntitySpecification(criteria.getEmployeName(),
 Project_.project, Project_.name);
      Type Parameters:
      X - The type of the attribute which is filtered.
      OTHER - The type of the referenced entity.
      Parameters:
      filter - the filter object which contains a value, which needs to match or a flag if emptiness is checked.
      reference - the attribute of the static metamodel for the referring entity.
      valueField - the attribute of the static metamodel of the referred entity, where the equality should be checked.
      Returns:
      a Specification

    • buildReferringEntitySpecification

      protected <OTHER, MISC, X extends Comparable<? super X>> org.springframework.data.jpa.domain.Specification<ENTITY> buildReferringEntitySpecification(RangeFilter<X> filter, Function<jakarta.persistence.criteria.Root<ENTITY>,jakarta.persistence.criteria.SetJoin<MISC,OTHER>> functionToEntity, Function<jakarta.persistence.criteria.SetJoin<MISC,OTHER>,jakarta.persistence.criteria.Expression<X>> entityToColumn)
      Helper function to return a specification for filtering on one-to-many or many-to-many reference.Where equality, less than, greater than and less-than-or-equal-to and greater-than-or-equal-to and null/non-null conditions are supported. Usage: 
      
   Specification<Employee> specByEmployeeId = buildReferringEntitySpecification(
          criteria.getEmployeId(),
          root -> root.get(Project_.company).join(Company_.employees),
          entity -> entity.get(Employee_.id));
   Specification<Employee> specByProjectName = buildReferringEntitySpecification(
          criteria.getProjectName(),
          root -> root.get(Project_.project)
          entity -> entity.get(Project_.name));
      Type Parameters:
      X - The type of the attribute which is filtered.
      OTHER - The type of the referenced entity.
      MISC - The type of the entity which is the last before the OTHER in the chain.
      Parameters:
      filter - the filter object which contains a value, which needs to match or a flag if emptiness is checked.
      functionToEntity - the function, which joins he current entity to the entity set, on which the filtering is applied.
      entityToColumn - the function, which of the static metamodel of the referred entity, where the equality should be checked.
      Returns:
      a Specification

    • equalsSpecification

      protected <X> org.springframework.data.jpa.domain.Specification<ENTITY> equalsSpecification(Function<jakarta.persistence.criteria.Root<ENTITY>,jakarta.persistence.criteria.Expression<X>> metaclassFunction, X value)
      Generic method, which based on a Root<ENTITY> returns an Expression which type is the same as the given 'value' type.
      Type Parameters:
      X - The type of the attribute which is filtered.
      Parameters:
      metaclassFunction - function which returns the column which is used for filtering.
      value - the actual value to filter for.
      Returns:
      a Specification.

    • notEqualsSpecification

      protected <X> org.springframework.data.jpa.domain.Specification<ENTITY> notEqualsSpecification(Function<jakarta.persistence.criteria.Root<ENTITY>,jakarta.persistence.criteria.Expression<X>> metaclassFunction, X value)
      Generic method, which based on a Root<ENTITY> returns an Expression which type is the same as the given 'value' type.
      Type Parameters:
      X - The type of the attribute which is filtered.
      Parameters:
      metaclassFunction - function which returns the column which is used for filtering.
      value - the actual value to exclude for.
      Returns:
      a Specification.

    • likeUpperSpecification

      protected org.springframework.data.jpa.domain.Specification<ENTITY> likeUpperSpecification(Function<jakarta.persistence.criteria.Root<ENTITY>,jakarta.persistence.criteria.Expression<String>> metaclassFunction, String value)

      likeUpperSpecification.

      Parameters:
      metaclassFunction - a Function object.
      value - a String object.
      Returns:
      a Specification object.

    • doesNotContainSpecification

      protected org.springframework.data.jpa.domain.Specification<ENTITY> doesNotContainSpecification(Function<jakarta.persistence.criteria.Root<ENTITY>,jakarta.persistence.criteria.Expression<String>> metaclassFunction, String value)

      doesNotContainSpecification.

      Parameters:
      metaclassFunction - a Function object.
      value - a String object.
      Returns:
      a Specification object.

    • byFieldSpecified

      protected <X> org.springframework.data.jpa.domain.Specification<ENTITY> byFieldSpecified(Function<jakarta.persistence.criteria.Root<ENTITY>,jakarta.persistence.criteria.Expression<X>> metaclassFunction, boolean specified)

      byFieldSpecified.

      Type Parameters:
      X - a X object.
      Parameters:
      metaclassFunction - a Function object.
      specified - a boolean.
      Returns:
      a Specification object.

    • byFieldEmptiness

      protected <X> org.springframework.data.jpa.domain.Specification<ENTITY> byFieldEmptiness(Function<jakarta.persistence.criteria.Root<ENTITY>,jakarta.persistence.criteria.Expression<Set<X>>> metaclassFunction, boolean specified)

      byFieldEmptiness.

      Type Parameters:
      X - a X object.
      Parameters:
      metaclassFunction - a Function object.
      specified - a boolean.
      Returns:
      a Specification object.

    • valueIn

      protected <X> org.springframework.data.jpa.domain.Specification<ENTITY> valueIn(Function<jakarta.persistence.criteria.Root<ENTITY>,jakarta.persistence.criteria.Expression<X>> metaclassFunction, Collection<X> values)

      valueIn.

      Type Parameters:
      X - a X object.
      Parameters:
      metaclassFunction - a Function object.
      values - a Collection object.
      Returns:
      a Specification object.

    • valueNotIn

      protected <X> org.springframework.data.jpa.domain.Specification<ENTITY> valueNotIn(Function<jakarta.persistence.criteria.Root<ENTITY>,jakarta.persistence.criteria.Expression<X>> metaclassFunction, Collection<X> values)

      valueNotIn.

      Type Parameters:
      X - a X object.
      Parameters:
      metaclassFunction - a Function object.
      values - a Collection object.
      Returns:
      a Specification object.

    • greaterThanOrEqualTo

      protected <X extends Comparable<? super X>> org.springframework.data.jpa.domain.Specification<ENTITY> greaterThanOrEqualTo(Function<jakarta.persistence.criteria.Root<ENTITY>,jakarta.persistence.criteria.Expression<X>> metaclassFunction, X value)

      greaterThanOrEqualTo.

      Type Parameters:
      X - a X object.
      Parameters:
      metaclassFunction - a Function object.
      value - a X object.
      Returns:
      a Specification object.

    • greaterThan

      protected <X extends Comparable<? super X>> org.springframework.data.jpa.domain.Specification<ENTITY> greaterThan(Function<jakarta.persistence.criteria.Root<ENTITY>,jakarta.persistence.criteria.Expression<X>> metaclassFunction, X value)

      greaterThan.

      Type Parameters:
      X - a X object.
      Parameters:
      metaclassFunction - a Function object.
      value - a X object.
      Returns:
      a Specification object.

    • lessThanOrEqualTo

      protected <X extends Comparable<? super X>> org.springframework.data.jpa.domain.Specification<ENTITY> lessThanOrEqualTo(Function<jakarta.persistence.criteria.Root<ENTITY>,jakarta.persistence.criteria.Expression<X>> metaclassFunction, X value)

      lessThanOrEqualTo.

      Type Parameters:
      X - a X object.
      Parameters:
      metaclassFunction - a Function object.
      value - a X object.
      Returns:
      a Specification object.

    • lessThan

      protected <X extends Comparable<? super X>> org.springframework.data.jpa.domain.Specification<ENTITY> lessThan(Function<jakarta.persistence.criteria.Root<ENTITY>,jakarta.persistence.criteria.Expression<X>> metaclassFunction, X value)

      lessThan.

      Type Parameters:
      X - a X object.
      Parameters:
      metaclassFunction - a Function object.
      value - a X object.
      Returns:
      a Specification object.

    • wrapLikeQuery

      protected String wrapLikeQuery(String txt)

      wrapLikeQuery.

      Parameters:
      txt - a String object.
      Returns:
      a String object.

    • distinct

      protected org.springframework.data.jpa.domain.Specification<ENTITY> distinct(boolean distinct)

      distinct.

      Parameters:
      distinct - a boolean.
      Returns:
      a Specification object.