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https://issues.apache.org/jira/browse/FLINK-40545?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Timo Walther updated FLINK-40545:
---------------------------------
Component/s: Table SQL / API
> Add parseJson() and tryParseJson() Table API expression methods
> ---------------------------------------------------------------
>
> Key: FLINK-40545
> URL: https://issues.apache.org/jira/browse/FLINK-40545
> Project: Flink
> Issue Type: Improvement
> Components: Table SQL / API
> Reporter: Ramin Gharib
> Assignee: Ramin Gharib
> Priority: Major
>
> {{PARSE_JSON}} and {{TRY_PARSE_JSON}} parse a JSON string into a
> {{{}VARIANT{}}}. They are
> available in SQL and as {{{}BuiltInFunctionDefinitions{}}}, but unlike almost
> every other JSON
> function they have no dedicated Table API expression method. Users must fall
> back to the
> generic {{{}call(){}}}:
> {code:java}
> call("PARSE_JSON", $("f")) // string name
> call(BuiltInFunctionDefinitions.PARSE_JSON, $("f")) // or the definition
> {code}
> Most JSON functions already expose a fluent method on {{BaseExpressions}} —
> {{{}jsonQuote(){}}},
> {{{}jsonUnquote(){}}}, {{{}isJson(){}}}, {{{}jsonExists(){}}},
> {{{}jsonValue(){}}}, {{{}jsonQuery(){}}}, etc.
> {{{}PARSE_JSON{}}}/{{{}TRY_PARSE_JSON{}}} are the exception, which is
> inconsistent and hurts
> discoverability.
> h3. Proposed change
> Add the two methods to {{BaseExpressions}} following the existing
> {{jsonQuote()}} pattern:
> {code:java}
> public OutType parseJson() {
> return toApiSpecificExpression(unresolvedCall(PARSE_JSON,
> objectToExpression(toExpr())));
> }
> public OutType tryParseJson() {
> return toApiSpecificExpression(unresolvedCall(TRY_PARSE_JSON,
> objectToExpression(toExpr())));
> }
> {code}
> Usage becomes:
> {code:java}
> $("f").parseJson() // instead of call("PARSE_JSON", $("f"))
> $("f").tryParseJson()
> {code}
> Also update for parity:
> * PyFlink Table API ({{{}flink-python/pyflink/table/expression.py{}}})
> * Table API function documentation (JSON functions section)
> h3. Context
> Surfaced in the FLINK-37926 review (VARIANT-to-constructed casts): the cast
> tests use
> {{call("PARSE_JSON", ...)}} because no Table API method exists.
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