Airblader commented on a change in pull request #16776:
URL: https://github.com/apache/flink/pull/16776#discussion_r688547801
##########
File path:
flink-table/flink-table-api-java/src/main/java/org/apache/flink/table/api/internal/BaseExpressions.java
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@@ -1323,4 +1327,211 @@ public OutType jsonExists(String path,
JsonExistsOnError onError) {
public OutType jsonExists(String path) {
return toApiSpecificExpression(unresolvedCall(JSON_EXISTS, toExpr(),
valueLiteral(path)));
}
+
+ /**
+ * Extracts a scalar from a JSON string.
+ *
+ * <p>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 {@link DataTypes#STRING()}. Using {@param returningType}
a different type can
+ * be chosen, with the following types being supported:
+ *
+ * <ul>
+ * <li>{@link LogicalTypeRoot#VARCHAR}
+ * <li>{@link LogicalTypeRoot#BOOLEAN}
+ * <li>{@link LogicalTypeRoot#INTEGER}
+ * <li>{@link LogicalTypeRoot#DOUBLE}
+ * </ul>
+ *
+ * <p>For empty path expressions or errors a behavior can be defined to
either return {@code
+ * null}, raise an error or return a defined default value instead.
+ *
+ * <p>Examples:
+ *
+ * <pre>{@code
+ * // STRING: "true"
+ * lit("{\"a\": true}").jsonValue("$.a")
+ *
+ * // BOOLEAN: true
+ * lit("{\"a\": true}").jsonValue("$.a", DataTypes.BOOLEAN())
+ *
+ * // BOOLEAN: "false"
+ * lit("{\"a\": true}").jsonValue("lax $.b",
+ * JsonValueOnEmptyOrError.DEFAULT, false,
JsonValueOnEmptyOrError.NULL, null)
Review comment:
That's true, but I think it's worth having the extra constant here just
to make it easier for users to align Table API with SQL.
##########
File path:
flink-table/flink-table-api-java/src/main/java/org/apache/flink/table/api/internal/BaseExpressions.java
##########
@@ -1323,4 +1327,211 @@ public OutType jsonExists(String path,
JsonExistsOnError onError) {
public OutType jsonExists(String path) {
return toApiSpecificExpression(unresolvedCall(JSON_EXISTS, toExpr(),
valueLiteral(path)));
}
+
+ /**
+ * Extracts a scalar from a JSON string.
+ *
+ * <p>This method searches a JSON string for a given path expression and
returns the value if
+ * the value at that path is scalar. Non-scalar values cannot be returned.
By default, the value
+ * is returned as {@link DataTypes#STRING()}. Using {@param returningType}
a different type can
+ * be chosen, with the following types being supported:
+ *
+ * <ul>
+ * <li>{@link LogicalTypeRoot#VARCHAR}
+ * <li>{@link LogicalTypeRoot#BOOLEAN}
+ * <li>{@link LogicalTypeRoot#INTEGER}
+ * <li>{@link LogicalTypeRoot#DOUBLE}
+ * </ul>
+ *
+ * <p>For empty path expressions or errors a behavior can be defined to
either return {@code
+ * null}, raise an error or return a defined default value instead.
+ *
+ * <p>Examples:
+ *
+ * <pre>{@code
+ * // STRING: "true"
+ * lit("{\"a\": true}").jsonValue("$.a")
+ *
+ * // BOOLEAN: true
+ * lit("{\"a\": true}").jsonValue("$.a", DataTypes.BOOLEAN())
+ *
+ * // BOOLEAN: "false"
+ * lit("{\"a\": true}").jsonValue("lax $.b",
+ * JsonValueOnEmptyOrError.DEFAULT, false,
JsonValueOnEmptyOrError.NULL, null)
Review comment:
That's true, but I think it's worth having the extra constant here just
to make it easier for users to align Table API with SQL. It really doesn't cost
us anything.
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