There can be several problems in the code.
The first, you are using LocalDateTime.now().toString() as part of the filename of the CSV file in which the information will be saved. It will give you something like:
2021-05-02T23:42:03.282
In some operating systems - you mentioned MacOS but it should allow you to create a file with that name - this name can be a possible cause of problems; please consider use something less error prone like System.currentTimeMillis:
String filename = "table_name" + System.currentTimeMillis() + ".csv";
ExportUtil.exportFile(db, "table_name", new File(filename));
Having said that, please, be aware that in the AWS Lambda function you probably will need to store your results in external storage, typically S3: you have the ability to write to the filesystem but it is usually of relevance when working with temporary files, not with persistent storage. Please, consider for instance the following code snippet.
// Here you can have a problem as well when trying to access the filesystem
// to read the Access file, but the API does not give you another option
// Probably deploying (https://docs.aws.amazon.com/lambda/latest/dg/lambda-java.html)
// your lambda function as a container (https://docs.aws.amazon.com/lambda/latest/dg/java-image.html)
// and include your database file
Database db = DatabaseBuilder.open(new File("java-runtime/src/access_db_file.accdb"));
System.out.println(db.getTableNames());
String filename = "table_name" + System.currentTimeMillis() + ".csv";
// Instead of writing to a file, write to a byte array through a writer
try (ByteArrayOutputStream output = new ByteArrayOutputStream();
BufferedWriter writer = new BufferedWriter(
new OutputStreamWriter(output));
) {
// Dump data
ExportUtil.exportWriter(db, "table_name", writer);
// Just in case
writer.flush();
// Get actual information
byte[] data = output.toByteArray();
// Save data to S3: please, consider refactor and organize the code
S3Client s3 = ...; // Initialize as appropriate
String bucketName = "your-bucket";
String objectKey = filename; // object key, same as filename, for example
// Perform actual S3 request
PutObjectResponse response = s3.putObject(
PutObjectRequest.builder()
.bucket(bucketName)
.key(objectKey)
.build(),
RequestBody.fromBytes(data)
);
} catch (IOException e) {
e.printStackTrace();
}
From a totally different perspective, the problem can be caused because table_name is a linked table. When you create a linked table, you need to define the path to the linked information: in your case, probably this information is stored in C:\Users\john.doe.ctr\Desktop\Work\table_name in the original computer of your client.
If you have the MS Access program, you can verify if that is the actual problem with the help of Linked Table Manager.
If you do not have the MS Access program, you can use the Database class as well. Please, consider the following example:
Database db = DatabaseBuilder.open(new File("java-runtime/src/access_db_file.accdb"));
Table table = db.getTable("table_name");
boolean isLinkedTable = db.isLinkedTable(table);
If the table is linked you need two things: on one hand, the linked information itself and, on the other, you need to provide a convenient implementation of the LinkResolver interface, probably by extending CustomLinkResolver. This interface basically provides you the ability to map the location of a linked table to a different path. Please, consider review this test for a convenient example of such as implementation.
For instance, think in something like this:
public class RemapLinkResolver implements LinkResolver {
// Maintain a correspondence between the original linked db file
// and the same db in your new filesystem
private Map<String, String> dbLinkeeFileRemap = new HashMap<>();
public void remap(String originalLinkeeFileName, String newLinkeeFileName) {
this.dbLinkeeFileRemap.put(originalLinkeeFileName, newLinkeeFileName);
}
@Override
public Database resolveLinkedDatabase(Database linkerDb,
String linkeeFileName)
throws IOException {
// if linker is read-only, open linkee read-only
boolean readOnly = ((linkerDb instanceof DatabaseImpl) ?
((DatabaseImpl)linkerDb).isReadOnly() : false);
String newLinkeeFileName = this. dbLinkeeFileRemap.get(linkeeFileName);
if (newLinkeeFileName != null) {
return new DatabaseBuilder(new File(newLinkeeFileName))
.setReadOnly(readOnly).open();
}
// Fallback to default
return LinkResolver.DEFAULT.resolveLinkedDatabase(linkerDb, linkeeFileName);
}
}
Then, use it in your code:
Database db = DatabaseBuilder.open(new File("java-runtime/src/access_db_file.accdb"));
RemapLinkResolver linkResolver = new RemapLinkResolver();
linkResolver.remap(
"C:\Users\john.doe.ctr\Desktop\Work\table_name",
"java-runtime/src/table_name.accdb"
);
db.setLinkResolver(linkResolver);
// Continue as usual
I hope you get the idea, please, adapt the paths and, in general, the code as appropriate.
