將 TIMESTAMPDIFF 與 JPA 條件查詢一起使用，並將休眠作為提供程序

Question

我有一個包含列 setup 和 release 的數據表，它們都包含時間戳。 我的目標是使用 CriteriaQuery 創建以下 SQL 查詢的等效項。

SQL 查詢： SELECT TIMESTAMPDIFF(SECOND, setup, released)) as sum_duration FROM calls

CriteriaBuilder#diff()函數顯然不起作用，因為它需要數字參數，所以我嘗試使用CriteriaBuilder#function ：

EntityManager entityManager = emProvider.get();

CriteriaBuilder criteriaBuilder = entityManager.getCriteriaBuilder();

CriteriaQuery<Integer> query = criteriaBuilder.createQuery();

Root<Thingy> thingyRoot = query.from(Thingy.class);

Path<DateTime> setup = root.get("setup");
Path<DateTime> release = root.get("release");

Expression secondLiteral = criteriaBuilder.literal("SECOND");

Expression func = criteriaBuilder.function("TIMESTAMPDIFF", Integer.class, secondLiteral, setup, release);

entityManager.createQuery(query).getResultList();

但是，當我嘗試運行此代碼時，它拋出了異常； 似乎文字沒有呈現為常量，而是呈現為參數：

java.lang.IllegalStateException: No data type for node: org.hibernate.hql.internal.ast.tree.MethodNode 
 \-[METHOD_CALL] MethodNode: '('
    +-[METHOD_NAME] IdentNode: 'TIMESTAMPDIFF' {originalText=TIMESTAMPDIFF}
    \-[EXPR_LIST] SqlNode: 'exprList'
       +-[NAMED_PARAM] ParameterNode: '?' {name=param0, expectedType=null}
       +-[DOT] DotNode: 'cdr0_.setup' {propertyName=setup,dereferenceType=ALL,propertyPath=setup,path=generatedAlias0.setup,tableAlias=cdr0_,className=com.vtsl.domain.CDR,classAlias=generatedAlias0}
       |  +-[ALIAS_REF] IdentNode: 'cdr0_.id' {alias=generatedAlias0, className=com.vtsl.domain.CDR, tableAlias=cdr0_}
       |  \-[IDENT] IdentNode: 'setup' {originalText=setup}
       \-[DOT] DotNode: 'cdr0_.release' {propertyName=release,dereferenceType=ALL,propertyPath=release,path=generatedAlias0.release,tableAlias=cdr0_,className=com.vtsl.domain.CDR,classAlias=generatedAlias0}
          +-[ALIAS_REF] IdentNode: 'cdr0_.id' {alias=generatedAlias0, className=com.vtsl.domain.CDR, tableAlias=cdr0_}
          \-[IDENT] IdentNode: 'release' {originalText=release}

所以我嘗試匿名覆蓋LiteralExpression#render以直接返回我提供給方法的字符串，但是這個異常。

java.lang.IllegalStateException: No data type for node: org.hibernate.hql.internal.ast.tree.MethodNode 
 \-[METHOD_CALL] MethodNode: '('
    +-[METHOD_NAME] IdentNode: 'TIMESTAMPDIFF' {originalText=TIMESTAMPDIFF}
    \-[EXPR_LIST] SqlNode: 'exprList'
       +-[IDENT] IdentNode: 'SECOND' {originalText=SECOND}
       +-[DOT] DotNode: 'cdr0_.setup' {propertyName=setup,dereferenceType=ALL,propertyPath=setup,path=generatedAlias0.setup,tableAlias=cdr0_,className=com.vtsl.domain.CDR,classAlias=generatedAlias0}
       |  +-[ALIAS_REF] IdentNode: 'cdr0_.id' {alias=generatedAlias0, className=com.vtsl.domain.CDR, tableAlias=cdr0_}
       |  \-[IDENT] IdentNode: 'setup' {originalText=setup}
       \-[DOT] DotNode: 'cdr0_.release' {propertyName=release,dereferenceType=ALL,propertyPath=release,path=generatedAlias0.release,tableAlias=cdr0_,className=com.vtsl.domain.CDR,classAlias=generatedAlias0}
          +-[ALIAS_REF] IdentNode: 'cdr0_.id' {alias=generatedAlias0, className=com.vtsl.domain.CDR, tableAlias=cdr0_}
          \-[IDENT] IdentNode: 'release' {originalText=release}

所以問題是：我怎樣才能修復我正在嘗試做的這個操作，或者實現最初的目標？

我正在使用 Hibernate，我的數據庫是 MySQL。

Answer 1

我碰到了同樣的問題： SECOND將被撇號包圍，查詢將引發異常。

我通過以下代碼解決了這個問題：

CriteriaBuilder builder = em.getCriteriaBuilder();
CriteriaQuery<MyEntity> cq = builder.createQuery( MyEntity.class );
Root<MyEntity> root = cq.from( MyEntity.class );

javax.persistence.criteria.Expression<java.sql.Time> timeDiff = builder.function(
            "TIMEDIFF",
            java.sql.Time.class,
            root.<Date>get( "endDate" ),
            root.<Date>get( "startDate" ) );
javax.persistence.criteria.Expression<Integer> timeToSec = builder.function(
            "TIME_TO_SEC",
            Integer.class,
            timeDiff );

//lessThanOrEqualTo 60 minutes
cq.where( builder.lessThanOrEqualTo( timeToSec, 3600 ) );

return em.createQuery( cq ).getResultList();

這給了我相同的結果。

Answer 2

這是等效的JPA標准查詢的說明

SELECT * *從TIMESTAMPDIFF（SECOND，設置，已釋放）<3600;

首先，您必須創建單元表達式並從BasicFunctionExpression進行擴展，對於BasicFunctionExpression ，它將“ SECOND”參數作為單元並僅覆蓋其rendor(RenderingContext renderingContext)方法。

import java.io.Serializable;
import org.hibernate.query.criteria.internal.CriteriaBuilderImpl;
import org.hibernate.query.criteria.internal.compile.RenderingContext;
import org.hibernate.query.criteria.internal.expression.function.BasicFunctionExpression;

public class UnitExpression extends BasicFunctionExpression<String> implements Serializable {

  public UnitExpression(CriteriaBuilderImpl criteriaBuilder, Class<String> javaType,
      String functionName) {
    super(criteriaBuilder, javaType, functionName);
  }

  @Override
  public String render(RenderingContext renderingContext) {
    return getFunctionName();
  }
}

那么您可以在JPA條件查詢中使用此單位表達式。

EntityManager entityManager = emProvider.get();
CriteriaBuilder criteriaBuilder = entityManager.getCriteriaBuilder();
Root<Calls> thingyRoot = query.from(Calls.class);

    Expression<String> second = new UnitExpression(null, String.class, "SECOND");
    Expression<Integer> timeInSec = cb.function(
        "TIMESTAMPDIFF",
        Integer.class,
        second ,
        root.<Timestamp>get("setup"),
        root.<Timestamp>get("release"));
    List<Predicate> conditions = new ArrayList<>();
    conditions.add(cb.lessThan(timeInSec, 3600));
    cq.where(conditions.toArray(new Predicate[]{}));
    return session.createQuery(cq);

這是工作。

Answer 3

CASE WHEN 1=1 THEN TIMESTAMPDIFF(SECOND,startDatetime,endDatetime) ELSE 0 END

用case語句模擬它。

Answer 4

這是一個比 Kalid Shah 的解決方案更通用的解決方案。

基本上，我們需要的是一個自定義的“不透明文字” Expression類，它能夠將任意標記表達式（如MONTH 、 YEAR 、 INTERVAL 1 DAY等）作為函數參數傳遞給 MySQL：

import javax.persistence.criteria.CriteriaBuilder;

import org.hibernate.query.criteria.internal.CriteriaBuilderImpl;
import org.hibernate.query.criteria.internal.compile.RenderingContext;
import org.hibernate.query.criteria.internal.expression.LiteralExpression;

/**
 * Represents an opaque literal that gets pass through JPA unaltered into SQL.
 */
@SuppressWarnings("serial")
public class OpaqueLiteralExpression extends LiteralExpression<Void> {

    private final String value;

    public OpaqueLiteralExpression(CriteriaBuilderImpl builder, String value) {
        super(builder, Void.class, null);
        if (value == null)
            throw new IllegalArgumentException("null value");
        this.value = value;
    }

// ExpressionImpl

    @Override
    public String render(RenderingContext renderingContext) {
        return this.value;
    }
}

然后你可以像這樣使用它：

final Expression<LocalDate> birthDate = student.get(Student_.birthDate);
final Expression<Integer> age = builder.function("TIMESTAMPDIFF", Integer.class,
  new OpaqueLiteralExpression(builder, "YEAR"), birthDate, LocalDate.now());