added ddi-pdf exporter written in Jython

.gitignore

@@ -2,4 +2,5 @@ target
 .vscode
 .idea
 .flattened-pom.xml
-pom.xml.versionsBackup
+pom.xml.versionsBackup
+src/test/resources/fop/output.pdf

README.md

@@ -6,11 +6,11 @@ Supported Dataverse versions: 6.0 - recent.
 
 ## Installation
 
-If you haven’t already configured it, set the [dataverse-spi-exporters-directory](https://guides.dataverse.org/en/latest/installation/config.html#dataverse-spi-exporters-directory) configuration value first. Then navigate to the configured directory and download the [JAR file](https://repo1.maven.org/maven2/io/github/erykkul/dataverse-transformer-exporter/1.0.4/dataverse-transformer-exporter-1.0.4-jar-with-dependencies.jar) together with the examples you want to try out:
+If you haven’t already configured it, set the [dataverse-spi-exporters-directory](https://guides.dataverse.org/en/latest/installation/config.html#dataverse-spi-exporters-directory) configuration value first. Then navigate to the configured directory and download the [JAR file](https://repo1.maven.org/maven2/io/github/erykkul/dataverse-transformer-exporter/1.0.5/dataverse-transformer-exporter-1.0.5-jar-with-dependencies.jar) together with the examples you want to try out:
 
 ```shell
 # download the jar
-wget -O transformer-exporter-1.0.4.jar https://repo1.maven.org/maven2/io/github/erykkul/dataverse-transformer-exporter/1.0.4/dataverse-transformer-exporter-1.0.4-jar-with-dependencies.jar
+wget -O transformer-exporter-1.0.5.jar https://repo1.maven.org/maven2/io/github/erykkul/dataverse-transformer-exporter/1.0.5/dataverse-transformer-exporter-1.0.5-jar-with-dependencies.jar
 # download the hello-world example
 mkdir hello-world
 wget -O hello-world/config.json https://raw.githubusercontent.com/erykkul/dataverse-transformer-exporter/main/examples/hello-world/config.json
@@ -102,6 +102,10 @@ This exporter copies only the title, the author names and the filenames of the d
 
 This exporter takes JSON input from a prerequisite exporter (`short_example_py` by default), and displays it as HTML. It is written in Python. In order to change the JSON input for this exporter, change the `prerequisiteFormatName` value in the `config.json` to the format name of the exporter you wish to use as input.
 
+### DDI PDF codebook
+
+This exporter is entirely based on the [DDI PDF Exporter](https://github.com/gdcc/exporter-ddipdf). It is simply a port of that exporter into Python (Jython). It illustrates how to convert XML input to PDF in an exporter.
+
 ## Developer guide
 
 The easiest way to start is to write JavasCript code. You can use the provided [Croissant](/examples/croissant/js/croissant.js) code as the start point. You will need to restart the server after changing that code. Note that the exporters use caching, you will need to either to wait until the cache is expired or delete the cached exporter output manually to see the changes.

examples/ddi-pdf/config.json

@@ -0,0 +1,8 @@
+{
+    "formatName": "ddi_pdf",
+    "harvestable": false,
+    "availableToUsers": true,
+    "mediaType": "application/pdf",
+    "displayName": "DDI pdf codebook",
+    "prerequisiteFormatName": "ddi"
+}

examples/ddi-pdf/transformer.py

@@ -0,0 +1,31 @@
+from java.io import ByteArrayInputStream, ByteArrayOutputStream, File
+from java.lang import System
+from java.util import Base64
+from javax.xml.transform import TransformerFactory
+from javax.xml.transform.sax import SAXResult
+from javax.xml.transform.stream import StreamSource
+from org.apache.fop.apps import FopFactory, MimeConstants
+
+localeEnvVar = System.getenv().get("LANG") if System.getenv().get("LANG") else "en"
+if localeEnvVar.index(".") > 0:
+    localeEnvVar = localeEnvVar[0 : localeEnvVar.index(".")]
+if localeEnvVar.index("_") > 0:
+    localeEnvVar = localeEnvVar[0 : localeEnvVar.index("_")]
+
+fopFactory = FopFactory.newInstance(File(".").toURI())
+foUserAgent = fopFactory.newFOUserAgent()
+out = ByteArrayOutputStream()
+fop = fopFactory.newFop(MimeConstants.MIME_PDF, foUserAgent, out)
+
+factory = TransformerFactory.newInstance()
+factory.setURIResolver(
+    lambda href, base: StreamSource(File(path + "/xslt/" + href))
+)
+transformer = factory.newTransformer(StreamSource(File(path + "/xslt/ddi-to-fo.xsl")))
+transformer.setParameter("language-code", localeEnvVar)
+src = StreamSource(ByteArrayInputStream(Base64.getDecoder().decode(x["base64"])))
+saxRes = SAXResult(fop.getDefaultHandler())
+
+transformer.transform(src, saxRes)
+
+res["base64"] = Base64.getEncoder().encodeToString(out.toByteArray())