Add support for CASE statements #1844
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spring-projects-issues added the status: waiting-for-triage 
mp911de added type: enhancement 
| */ | ||
| public class CaseExpression extends AbstractSegment implements Expression { | ||
| private final List<When> whenList = new ArrayList<>(); | ||
| private final Literal other; |
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other is a undescriptive as it gets. I guess we can't use else or default since those are Java keywords.
But elseBranch would be a better name, or maybe whenElse.
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Also other should be an Expression, not constraint to a Literal
| */ | ||
| public CaseExpression when(When condition) { | ||
| this.whenList.add(condition); | ||
| return new CaseExpression(whenList, other); |
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This looks like it uses CaseExpression as an immutable, but it actually modifies the whenList. We should avoid that modification.
| */ | ||
| public class When extends AbstractSegment { | ||
| private final Expression condition; | ||
| private final Literal value; |
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To answer your question: Yes, please make value an expression.
| * @since 3.4 | ||
| */ | ||
| public class When extends AbstractSegment { | ||
| private final Expression condition; |
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condition should be an actual Condition
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Note: there are other forms of CASE expressions, where you have an expression to start with and in each branch an expression to compare it to. See https://modern-sql.com/feature/case
But that is not what we are doing here.
| Thanks for the review @schauder. I think I addressed all your comments. |
Minor formatting. Adding author tag in Javadoc. Fixing warnings. Original pull request #1844
| Thanks. That is polished and merged. |
4 participants
This PR add supports for CASE statements. Added 4 new types:
CaseExpressionandWhenplus their respective visitors.Also I changed the order of visitors in
TypedSingleConditionRenderSupport. BecauseConditionextendsExpressiontheExpressionVisitorwas used forConditions.Question: Should I add support for any
Expressionin the THEN and OTHER clause (versusLiteralnow)?