I have a CSV template file, say, having 10 columns.
I would like to load this CSV file template, and then write data to the relevant cells(say only to 5 of the 10 cells) through a java program.
I went through JSAPAR, SuperCSV etc, but am not sure whether these libraries have the "stuff" what exactly I need.
Is there any framework supporting this kind of operations?
Checkout freemarker: http://freemarker.org/
Open your text file.
Enter freemarker paramerters for required cells.
Your template file may look something like below:
"Templatetext1","text2","text4", "${myVal4}",${myVal5}","text6", ${myVal7}",${myVal8}",${myVal9}","textInCell10"
Pass in the values, you have your csv from template.
If you want to pass for multiple rows you can use other elements like <#list> etc.
OpenCSV is generally considered the best CSV toolkit for Java. It's a very lightweight library that makes working with CSV dead simple. I would recommend looking at it since it's not among the list of things you've tried yet.
Related
I'm looking for ideas for an Open Source ETL or Data Processing software that can monitor a folder for CSV files, then open and parse the CSV.
For each CSV row the software will transform the CSV into a JSON format and make an API call to start a Camunda BPM process, passing the cell data as variables into the process.
Looking for ideas,
Thanks
You can use a Java WatchService or Spring FileSystemWatcher as discussed here with examples:
How to monitor folder/directory in spring?
referencing also:
https://www.baeldung.com/java-nio2-watchservice
Once you have picked up the CSV you can use my example here as inspiration or extend it: https://github.com/rob2universe/csv-process-starter specifically
https://github.com/rob2universe/csv-process-starter/blob/main/src/main/java/com/camunda/example/service/CsvConverter.java#L48
The example starts a configurable process for every row in the CSV and includes the content of the row as a JSON process data.
I wanted to limit the dependencies of this example. The CSV parsing logic applied is very simple. Commas in the file may break the example, special characters may not be handled correctly. A more robust implementation could replace the simple Java String .split(",") with an existing CSV parser library such as Open CSV
The file watcher would actually be a nice extension to the example. I may add it when I get around to it, but would also accept a pull request in case you fork my project.
I am working on a project to process data and, depending upon the contents of the data, format it for use by another system. Some of the data provided are not of use to that other system and some of it is so sparsely populated that it would be of no use - is there a way, using Freemarker, to prevent the output of a file at all based upon the contents of the data? I have tried using <#if> statements, but if the checks do not pass, I simply get a blank file output.
This is not up to FreeMarker, but to the software that calls it. FreeMarker doesn't create files, it just writes the output to a Writer. That Writer is provided by the software that calls FreeMarker. So that could implements a logic where the file isn't created until something non-whitespace is written, or could expose a directive to FreeMarker that drops the output file.
I'm, writing a Puppet (3.6.2) module that reads data fields from a CSV file via the extlookup function and I cannot figure out how to tell extlookup that the first line is the header field. Does extlookup support this? If not, can anyone recommend an external function I could import and use?
thanks,
PS - Yes I know about hiera, and having the data in YAML or JSON files but my requirement is CSV files only.
Brandon
The behavior of extlookup() is pretty well documented. It makes no special provision for column headers, which are by no means an inherent feature of CSV format. Indeed, if your header line is not readable as a data line, then your file is not CSV at all.
Supposing that your file is indeed valid CSV, the absolute simplest solution would be to ignore the issue. It presents a problem only if the first column heading duplicates an actual or potential data name. If it does not, then you will never look up or use the psuedo-value represented by the first row.
If your file in fact is not CSV on account of its first line, or if the first column name conflicts with a real data name, then it seems the next best alternative would be to just remove that line, or to avoid creating it in the first place. I don't see any reason why one of these should not be possible.
I know about heira, and having the data in YAML or JSON files but my requirement is CSV files only.
How sad. Do be aware that extlookup() has long been deprecated, and it was removed from Puppet 4.
I'm inclined to suggest you implement a translator from CSV to Hiera-friendly YAML, and use Hiera in your module. Alternatively, Hiera supports custom backends, and it's not too hard to write one. I am unaware of an existing CSV backend for Hiera, but you could write one. Ignoring a header line would then be under your control, and you would simultaneously achieve a measure of future-proofing.
Imagine I've created a new javascript framework, and want to showcase some examples that utilise it, and let other people add examples if they want. Crucially I want this to all be on github.
I imagine I would need to provide a template HTML document which includes the framework, and sorts out all the header and footer correctly. People would then add examples into the examples folder.
However, doing it this way, I would just end up with a long list of HTML files. What would I need to do if I wanted to add some sort of metadata about each example, like tags/author/date etc, which I could then provide search functionality on? If it was just me working on this, I think I would probably set up a database. But because it's a collaboration, this is a bit tricky.
Would it work if each HTML file had a corresponding entry in a JSON file listing all the examples where I could put this metadata? Would I be able to create some basic search functionality using this? Would it be a case of: Step 1 : create new example file, step 2: add reference to file and file metadata to JSON file?
A good example of something similar to what I want is wbond's package manager http://wbond.net/sublime_packages/community
(There is not going to be a lot of create/update/destroy going on - mainly just reading.
Check out this Javascript database: http://www.taffydb.com/
There are other Javascript databases that let you load JSON data and then do database operations. Taffy lets you search for documents.
It sounds like a good idea to me though - making HTML files and an associated JSON document that has meta data about it.
I'm using JFreeChart to generate line graphs from a simple array of integers.
However, I'd like to use a csv file for the input of the graph. Are there any applications which do it automatically? Also, my csv file will new entries appended every 3 seconds. How can I generate dynamic graphs? I will have to use these graphs in a swing application. Thanks!
I've had good luck with org.h2.tools.Csv, part of H2 Database. You might also look at org.jfree.data.io.CSV, "A utility class for reading CategoryDataset data from a CSV file."