Airblader commented on a change in pull request #16776:
URL: https://github.com/apache/flink/pull/16776#discussion_r687676394
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File path: flink-python/pyflink/table/expression.py
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@@ -1393,6 +1414,47 @@ def json_exists(self, path: str, on_error:
JsonExistsOnError = None) -> 'Express
else:
return _ternary_op("jsonExists")(self, path,
on_error._to_j_json_exists_on_error())
+ def json_value(self,
+ path: str,
+ returning_type: DataType = None,
+ on_empty: JsonValueOnEmptyOrError = None,
+ default_on_empty: Any = None,
+ on_error: JsonValueOnEmptyOrError = None,
+ default_on_error: Any = None) -> 'Expression':
+ """
+ Extracts a scalar from a JSON string.
+
+ This method searches a JSON string for a given path expression and
returns the value if the
+ value at that path is scalar. Non-scalar values cannot be returned. By
default, the value is
+ returned as `DataTypes.STRING()`. Using `returningType` a different
type can be chosen, with
+ types with the following type roots being supported:
+
+ * `VARCHAR`
+ * `BOOLEAN`
+ * `INTEGER`
+ * `DOUBLE`
+
+ For empty path expressions or errors a behavior can be defined to
either return `null`,
+ raise an error or return a defined default value instead.
+
+ Examples:
+ ::
+
+ >>> lit('{"a": true}').json_value('$.a')
+ >>> lit('{"a": true}').json_value('$.a', DataTypes.BOOLEAN())
+ >>> lit('{"a": true}').json_value('lax $.b', \
Review comment:
No, it isn't. I'll remove it to make it even more of a unique example.
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