wuchong commented on a change in pull request #15768:
URL: https://github.com/apache/flink/pull/15768#discussion_r620820408
##########
File path: docs/content/docs/dev/table/functions/udfs.md
##########
@@ -171,6 +171,52 @@ env.createTemporarySystemFunction("SubstringFunction", new
SubstringFunction(tru
{{< /tab >}}
{{< /tabs >}}
+You can use star (*) as one argument of the function call to act as a wildcard
in Table API,
+all columns in the table will be passed to the function at the corresponding
position.
+
+{{< tabs "64dd4129-6313-4904-b7e7-a1a0535822e9" >}}
+{{< tab "Java" >}}
+```java
+import org.apache.flink.table.api.*;
+import org.apache.flink.table.functions.ScalarFunction;
+import static org.apache.flink.table.api.Expressions.*;
+
+public static class JoinFunction extends ScalarFunction {
+
+ public String eval(String f0, String f1) {
+ return f0 + f1;
+ }
+}
+
+TableEnvironment env = TableEnvironment.create(...);
+
+// call function with $("*"), if MyTable has two string fields,
+// all of them will be passed to JoinFunction.
+env.from("MyTable").select(call(JoinFunction.class, $("*")));
Review comment:
I would suggest to show a more meaningful example here, e.g. `concat`?
```java
public static class MyConcatFunction extends ScalarFunction {
public String eval(Object... fields) {
return Arrays.stream(fields)
.map(Object::toString)
.collect(Collectors.joining(","));
}
}
TableEnvironment env = TableEnvironment.create(...);
// call function with $("*"), if MyTable has 3 fields (a, b, c),
// all of them will be passed to JoinFunction.
env.from("MyTable").select(call(MyConcatFunction.class, $("*")));
// it's equal to call function with explicitly selecting all columns
env.from("MyTable").select(call(MyConcatFunction.class, $("a"), $("b"),
$("c")));
```
##########
File path: docs/content/docs/dev/table/functions/udfs.md
##########
@@ -171,6 +171,52 @@ env.createTemporarySystemFunction("SubstringFunction", new
SubstringFunction(tru
{{< /tab >}}
{{< /tabs >}}
+You can use star (*) as one argument of the function call to act as a wildcard
in Table API,
+all columns in the table will be passed to the function at the corresponding
position.
+
+{{< tabs "64dd4129-6313-4904-b7e7-a1a0535822e9" >}}
+{{< tab "Java" >}}
+```java
+import org.apache.flink.table.api.*;
+import org.apache.flink.table.functions.ScalarFunction;
+import static org.apache.flink.table.api.Expressions.*;
+
+public static class JoinFunction extends ScalarFunction {
+
+ public String eval(String f0, String f1) {
+ return f0 + f1;
+ }
+}
+
+TableEnvironment env = TableEnvironment.create(...);
+
+// call function with $("*"), if MyTable has two string fields,
+// all of them will be passed to JoinFunction.
+env.from("MyTable").select(call(JoinFunction.class, $("*")));
Review comment:
And please also add an IT case for this to make sure this is supported
end-to-end.
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