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https://issues.apache.org/jira/browse/NIFI-5604?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16686842#comment-16686842
]
ASF GitHub Bot commented on NIFI-5604:
--------------------------------------
Github user patricker commented on a diff in the pull request:
https://github.com/apache/nifi/pull/3075#discussion_r233524977
--- Diff:
nifi-nar-bundles/nifi-standard-bundle/nifi-standard-processors/src/main/java/org/apache/nifi/processors/standard/GenerateTableFetch.java
---
@@ -450,7 +450,33 @@ public void onTrigger(final ProcessContext context,
final ProcessSessionFactory
// If there are no SQL statements to be generated, still
output an empty flow file if specified by the user
if (numberOfFetches == 0 &&
outputEmptyFlowFileOnZeroResults) {
- session.transfer((fileToProcess == null) ?
session.create() : session.create(fileToProcess), REL_SUCCESS);
+ FlowFile emptyFlowFile = (fileToProcess == null) ?
session.create() : session.create(fileToProcess);
+ Map<String, String> attributesToAdd = new HashMap<>();
+
+ attributesToAdd.put("generatetablefetch.tableName",
tableName);
+ if (columnNames != null) {
+
attributesToAdd.put("generatetablefetch.columnNames", columnNames);
+ }
+ whereClause = maxValueClauses.isEmpty() ? "1=1" :
StringUtils.join(maxValueClauses, " AND ");
+ if (StringUtils.isNotBlank(whereClause)) {
+
attributesToAdd.put("generatetablefetch.whereClause", whereClause);
+ }
+ final String maxColumnNames =
StringUtils.join(maxValueColumnNameList, ", ");
+ if (StringUtils.isNotBlank(maxColumnNames)) {
+
attributesToAdd.put("generatetablefetch.maxColumnNames", maxColumnNames);
+ }
+ attributesToAdd.put("generatetablefetch.limit", null);
--- End diff --
There is no existing test in `master`, but I think in normal circumstances
`limit` actually gets written as `"null"`.
```
if ((i == numberOfFetches - 1) && useColumnValsForPaging &&
(maxValueClauses.isEmpty() || customWhereClause != null)) {
maxValueClauses.add(columnForPartitioning + "
<= " + maxValueForPartitioning);
limit = null;
}
```
This value is then written using `String.valueOf(limit)`, which is going to
translate the `null` to `"null"`.
> Allow GenerateTableFetch to send empty flow files when no rows would be
> fetched
> -------------------------------------------------------------------------------
>
> Key: NIFI-5604
> URL: https://issues.apache.org/jira/browse/NIFI-5604
> Project: Apache NiFi
> Issue Type: Improvement
> Components: Extensions
> Reporter: Matt Burgess
> Assignee: Matt Burgess
> Priority: Major
>
> Currently, GenerateTableFetch will not output a flow file if there are no
> rows to be fetched. However, it may be desired (especially with incoming flow
> files) that a flow file be sent out even if GTF does not generate any SQL.
> This capability, along with the fragment attributes from NIFI-5601, would
> allow the user to handle this downstream.
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