clintropolis commented on code in PR #12968:
URL: https://github.com/apache/druid/pull/12968#discussion_r956552430
##########
processing/src/main/java/org/apache/druid/query/expression/NestedDataExpressions.java:
##########
@@ -442,38 +442,76 @@ public String name()
public Expr apply(List<Expr> args)
{
final List<NestedPathPart> parts =
getArg1JsonPathPartsFromLiteral(name(), args);
- class JsonValueExpr extends ExprMacroTable.BaseScalarMacroFunctionExpr
- {
- public JsonValueExpr(List<Expr> args)
- {
- super(name(), args);
+ if (args.size() == 3 && args.get(2).isLiteral()) {
+ final ExpressionType castTo = ExpressionType.fromString((String)
args.get(2).getLiteralValue());
+ if (castTo == null) {
+ throw new IAE("Invalid output type: [%s]",
args.get(2).getLiteralValue());
}
-
- @Override
- public ExprEval eval(ObjectBinding bindings)
+ class CastJsonValueExpr extends
ExprMacroTable.BaseScalarMacroFunctionExpr
{
- ExprEval input = args.get(0).eval(bindings);
- return ExprEval.bestEffortOf(
- NestedPathFinder.findLiteral(unwrap(input), parts)
- );
- }
+ public CastJsonValueExpr(List<Expr> args)
+ {
+ super(name(), args);
+ }
- @Override
- public Expr visit(Shuttle shuttle)
- {
- List<Expr> newArgs = args.stream().map(x ->
x.visit(shuttle)).collect(Collectors.toList());
- return shuttle.visit(new JsonValueExpr(newArgs));
- }
+ @Override
+ public ExprEval eval(ObjectBinding bindings)
+ {
+ ExprEval input = args.get(0).eval(bindings);
+ return ExprEval.bestEffortOf(
+ NestedPathFinder.findLiteral(unwrap(input), parts)
+ ).castTo(castTo);
+ }
- @Nullable
- @Override
- public ExpressionType getOutputType(InputBindingInspector inspector)
+ @Override
+ public Expr visit(Shuttle shuttle)
+ {
+ List<Expr> newArgs = args.stream().map(x ->
x.visit(shuttle)).collect(Collectors.toList());
+ return shuttle.visit(new CastJsonValueExpr(newArgs));
+ }
+
+ @Nullable
+ @Override
+ public ExpressionType getOutputType(InputBindingInspector inspector)
+ {
+ return castTo;
+ }
+ }
+ return new CastJsonValueExpr(args);
+ } else {
+ class JsonValueExpr extends ExprMacroTable.BaseScalarMacroFunctionExpr
{
- // we cannot infer the output type (well we could say it is 'STRING'
right now because is all we support...
- return null;
+ public JsonValueExpr(List<Expr> args)
Review Comment:
Yeah that's a good point. I think i'll remove them. The only one I'm a bit
partial to keeping is `struct` since longer term I sometimes imagine replacing
`COMPLEX<json>` with `STRUCT` and `VARIANT` types so that the engine can be
integrated a bit tighter with nested data columns. But, I can add it back
whenever we get to that point, so will remove it too for now.
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