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https://issues.apache.org/jira/browse/EDGENT-311?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15671122#comment-15671122
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Dale LaBossiere commented on EDGENT-311:
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Yes, the API is designed only for PreparedStatement. As the javadoc for
ParameterSetter indicates, the setter can set 0 or more parameters in the
prepared statement. So an empty/no-op ParameterSetter, as you've defined for
this case, is the way to go.
There doesn't seem to be sufficient value in making it easier than that to
support the no-param case, presumably by fattening the API with additional
executeStatement() variants. I suppose the API could also allow a null
ParameterSetter arg for the 0-param case, but would that really make a
meaningful difference? Or perhaps the javadoc for ParameterSetter just needs
to be more explicit and say to declare a no-op function for the 0 param case:
"(t,s)->{}"? Your thoughts?
Unless a compelling reason to support something other than PreparedStatement
can be made, I suspect the API won't be extended beyond that.
> support SELECT without any parameters in JdbcStreams
> ----------------------------------------------------
>
> Key: EDGENT-311
> URL: https://issues.apache.org/jira/browse/EDGENT-311
> Project: Edgent
> Issue Type: Improvement
> Components: Connectors
> Affects Versions: Apache Edgent 1.0.0
> Reporter: Rui Shen
> Priority: Minor
>
> Now I am trying to run a SELECT statement without parameters (e.g "select
> id,name,age from person") using JdbcStreams. But I found there is no
> straightforward way to do this. Looks like the APIs of JdbcStreams is
> designed for only prepared statement with parameters .
> However, I found a workaround to make this - always create a TStream with one
> tuple but in the ParameterSetter, does nothing. Although this works, it looks
> uncomfortable. Are you going to support this in the future release?
>
> Topology t = this.newTopology("testSelect_WithParameters");
> JdbcStreams db=new JdbcStreams(ds,(ds)=>
> {ds.getConnection()}
> );
> TStream<String> stream=t.collection(Arrays.asList(new String[]
> {"dummy"}
> )); // to execute the sql, always needs to create a TStream containing one
> tuple.
> ParameterSetter<String> paramSetter=(s,stmt)->{}; //do nothing here
> ResultsHandler<Object[], JsonObject> rh = (tuple, rs, exc, consumer) -> {};
> db.executeStatement(stream, "select id,name,age from person", paramSetter,rh);
>
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