List files under a folder within a Camel rest service - rest

Question

I am creating a rest service using Camel Rest DSL. Within the service I need to list all files under a folder and do some processing on them. PFB the code -
from("direct:postDocument")
.to("file:/home/s469457/service/content-util/composite?noop=true")
.setBody(constant(null))
.log("Scanning file ${file:name.noext}.${file:name.ext}...");
Please advice.
~ Arunava

Answer 1

I would suggest to write a processor or a bean to list files in directory. I think that would be more efficient and so much simpler. Using Camel's file component you would have to deal with intricacies you might not expect.
Regardless. You will need to do pollEnrich and afterwards aggregate the whole result. I also think that you would run into trouble and will not be able to read files multiple times, to solve that you might need to create idempotent repository, but when reading files there might be concurrency/file locking issues...
Here's some pseudocode to get you started if you want to go that way:
from("direct:listFiles")
.pollEnrich("file:"+getFullPath()+"?noop=true")
.aggregate(new AggregationStrategy {
public Exchange aggregate(Exchange oldExchange, Exchange newExchange) {
String filename = newExchange.getIn().getHeader("CamelFileName", String.class)
if (oldExchange == null) {
newExchange.getIn().setBody(new ArrayList<String>(Arrays.asList(filename)));
return newExchange;
} else {
...
}
})

Answer 2

//Camel Rest Api to list files
rest().path("/my-api/")
.get()
.produces("text/plain")
.to("direct:listFiles");
//Camel Route to list files
List<String> fileList = new ArrayList<String>();
from("direct:listFiles")
.loopDoWhile(body().isNotNull())
.pollEnrich("file:/home/s469457/service/content-util/composite?noop=true&recursive=true&idempotent=false&include=.*.csv")
.choice()
.when(body().isNotNull())
.process( new Processor(){
#Override
public void process(Exchange exchange) throws Exception {
File file = exchange.getIn().getBody(File.class);
fileList.add(file.getName());
}
})
.otherwise()
.process( new Processor(){
#Override
public void process(Exchange exchange) throws Exception {
if (fileList.size() != 0)
exchange.getOut().setBody(String.join("\n", fileList));
fileList.clear();
}
})
.end();