Camel - CSV Headers setting not working - csv

Question

I have CSV files without headers. Since I'm using 'useMaps' I want to specify the headers dynamically. If I set headers statically and then use in route it works fine as below Approach 1 -
#Component
public class BulkActionRoutes extends RouteBuilder {
#Override
public void configure() throws Exception {
CsvDataFormat csv = new CsvDataFormat(",");
csv.setUseMaps(true);
ArrayList<String> list = new ArrayList<String>();
list.add("DeviceName");
list.add("Brand");
list.add("status");
list.add("type");
list.add("features_c");
list.add("battery_c");
list.add("colors");
csv.setHeader(list);
from("direct:bulkImport")
.convertBodyTo(String.class)
.unmarshal(csv)
.split(body()).streaming()
.process(new Processor() {
#Override
public void process(Exchange exchange) throws Exception {
GenericObjectModel model = null;
HashMap<String, String> csvRecord = (HashMap<String, String>)exchange.getIn().getBody();
}
});
}
}
However, if the list is passed via Camel headers as below then it does not work Approach 2 -
#Component
public class BulkActionRoutes extends RouteBuilder {
#Override
public void configure() throws Exception {
CsvDataFormat csv = new CsvDataFormat(",");
csv.setUseMaps(true);
from("direct:bulkImport")
.convertBodyTo(String.class)
.process(new Processor() {
#Override
public void process(Exchange exchange) throws Exception {
ArrayList<String> fileHeaders = (ArrayList<String>)headers.get(Constants.FILE_HEADER_LIST);
if (fileHeaders != null && fileHeaders.size() > 0) {
csv.setHeader(fileHeaders);
}
}
})
.unmarshal(csv)
.split(body()).streaming()
.process(new Processor() {
#Override
public void process(Exchange exchange) throws Exception {
GenericObjectModel model = null;
HashMap<String, String> csvRecord = (HashMap<String, String>)exchange.getIn().getBody();
}
});
}
}
What could be missing in the Approach 2?

Answer 1

The big difference between approach 1 and 2 is the scope.
In approach 1 you fully configure the CSV data format. This is all done when the Camel Context is created, since the data format is shared within the Camel Context. When messages are processed, it is the same config for all messages.
In approach 2 you just configure the basics globally. The header configuration is within the route and therefore can change for every single message. Every message would overwrite the header configuration of the context-global data format instance.
Without being sure about this, I guess that it is not possible to change a context-global DataFormat inside the routes.
What would you expect (just for example) when messages are processed in parallel? They would overwrite the header config against each other.
As an alternative, you could use a POJO where you can do your dynamic marshal / unmarshal from Java code.