[GitHub] [nifi] MikeThomsen commented on a change in pull request #4678: NIFI-8031: Add UPSERT capability for MySQL in PutDatabaseRecord

[GitBox <gi...@apache.org>]

MikeThomsen commented on a change in pull request #4678:
URL: https://github.com/apache/nifi/pull/4678#discussion_r536077966



##########
File path: nifi-nar-bundles/nifi-standard-bundle/nifi-standard-processors/src/main/java/org/apache/nifi/processors/standard/db/impl/MySQLDatabaseAdapter.java
##########
@@ -35,4 +43,50 @@ public String unwrapIdentifier(String identifier) {
         // Removes double quotes and back-ticks.
         return identifier == null ? null : identifier.replaceAll("[\"`]", "");
     }
+
+    @Override
+    public boolean supportsUpsert() {
+        return true;
+    }
+
+    /**
+     * Tells How many times the column values need to be inserted into the prepared statement. Some DBs (such as MySQL) need the values specified twice in the statement,
+     * some need only to specify them once.
+     *
+     * @return An integer corresponding to the number of times to insert column values into the prepared statement for UPSERT, or -1 if upsert is not supported.
+     */
+    @Override
+    public int getTimesToAddColumnObjectsForUpsert() {
+        return 2;
+    }
+
+    @Override
+    public String getUpsertStatement(String table, List<String> columnNames, Collection<String> uniqueKeyColumnNames) {
+        Preconditions.checkArgument(!StringUtils.isEmpty(table), "Table name cannot be null or blank");
+        Preconditions.checkArgument(columnNames != null && !columnNames.isEmpty(), "Column names cannot be null or empty");
+        Preconditions.checkArgument(uniqueKeyColumnNames != null && !uniqueKeyColumnNames.isEmpty(), "Key column names cannot be null or empty");
+
+        String columns = columnNames.stream()
+                .collect(Collectors.joining(", "));
+
+        String parameterizedInsertValues = columnNames.stream()
+                .map(__ -> "?")
+                .collect(Collectors.joining(", "));
+
+        List<String> updateValues = new ArrayList<>();

Review comment:
       I think it would be more succinct as:
   
   ```
   String parameterizedUpdateValues = columnNames.stream().map(f => f + " = ?").collect(Collectors.joining(", "));
   ```




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