clintropolis commented on code in PR #12968:
URL: https://github.com/apache/druid/pull/12968#discussion_r955562617
##########
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, `get_path` is sort of a relic from my earliest prototypes, and used to
look a fair bit different (and only accepted 'jq' style paths), but does look
the same now. Will consolidate it. Maybe we need an easy way to alias native
expressions like we have for SQL expressions... I have a similar situation
going on with `json_object` which is a wrapper around the earlier prototype
`struct` function.
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