eclipse-rdf4jGH-5058: additional parser code (WIP)

core/model-vocabulary/src/main/java/org/eclipse/rdf4j/model/vocabulary/CSVW.java

@@ -75,6 +75,9 @@ public class CSVW {
 	/** csvw:header */
 	public static final IRI HEADER;
 
+	/** csvw:headerRowCount */
+	public static final IRI HEADER_ROW_COUNT;
+
 	/** csvw:lang */
 	public static final IRI LANG;
 
@@ -90,6 +93,9 @@ public class CSVW {
 	/** csvw:required */
 	public static final IRI REQUIRED;
 
+	/** csvw:skipRows */
+	public static final IRI SKIP_ROWS;
+
 	/** csvw:tableSchema */
 	public static final IRI TABLE_SCHEMA;
 
@@ -121,11 +127,13 @@ public class CSVW {
 		FORMAT = Vocabularies.createIRI(NAMESPACE, "format");
 		GROUP_CHAR = Vocabularies.createIRI(NAMESPACE, "groupChar");
 		HEADER = Vocabularies.createIRI(NAMESPACE, "header");
+		HEADER_ROW_COUNT = Vocabularies.createIRI(NAMESPACE, "headerRowCount");
 		LANG = Vocabularies.createIRI(NAMESPACE, "lang");
 		NAME = Vocabularies.createIRI(NAMESPACE, "name");
 		PROPERTY_URL = Vocabularies.createIRI(NAMESPACE, "propertyUrl");
 		QUOTE_CHAR = Vocabularies.createIRI(NAMESPACE, "quoteChar");
 		REQUIRED = Vocabularies.createIRI(NAMESPACE, "required");
+		SKIP_ROWS = Vocabularies.createIRI(NAMESPACE, "skipRows");
 		TABLE_SCHEMA = Vocabularies.createIRI(NAMESPACE, "tableSchema");
 		TABLES = Vocabularies.createIRI(NAMESPACE, "tables");
 		TITLE = Vocabularies.createIRI(NAMESPACE, "title");

core/rio/csvw/src/main/java/org/eclipse/rdf4j/rio/csvw/CSVWParser.java

@@ -60,8 +60,9 @@
  * Currently only "minimal mode" is supported
  *
  * @author Bart Hanssens
- * @see <a href="https://w3c.github.io/csvw/primer/">CSV on the Web Primer</a>
  *
+ * @see <a href="https://w3c.github.io/csvw/primer/">CSV on the Web Primer</a>
+ * @see <a href="https://w3c.github.io/csvw/metadata">Metadata Vocabulary for Tabular Data</a>
  * @since 5.1.0
  */
 public class CSVWParser extends AbstractRDFParser {
@@ -225,6 +226,8 @@ private CellParser getCellParser(Model metadata, Resource column) {
 		Models.getPropertyString(metadata, column, CSVW.DEFAULT).ifPresent(v -> parser.setDefaultValue(v));
 		Models.getPropertyString(metadata, column, CSVW.REQUIRED)
 				.ifPresent(v -> parser.setIsRequired(Boolean.parseBoolean(v)));
+		Models.getPropertyString(metadata, column, CSVW.VIRTUAL)
+				.ifPresent(v -> parser.setVirtual(Boolean.parseBoolean(v)));
 
 		// only useful for strings
 		Models.getPropertyString(metadata, column, CSVW.LANG).ifPresent(v -> parser.setLang(v));
@@ -297,8 +300,10 @@ private Optional<String> getFormat(Model metadata, Resource column) {
 	 * @param subject
 	 * @return aboutURL or null
 	 */
-	private String getAboutURL(Model metadata, Resource subject) {
-		return Models.getPropertyString(metadata, subject, CSVW.ABOUT_URL).orElse(null);
+	private String getAboutURL(Model metadata, Resource table) {
+		return Models.getPropertyString(metadata, table, CSVW.ABOUT_URL)
+				.orElse(Models.getPropertyString(metadata, getTableSchema(metadata, table), CSVW.ABOUT_URL)
+						.orElse(null));
 	}
 
 	/**
@@ -336,7 +341,7 @@ private void parseCSV(Model metadata, RDFHandler handler, URI csvFile, CellParse
 
 		// check for placeholder / column name that's being used to create subject IRI
 		int aboutIndex = getAboutIndex(aboutURL, cellParsers);
-		String placeholder = (aboutIndex > -1) ? cellParsers[aboutIndex].getName() : null;
+		String placeholder = (aboutIndex > -1) ? "{" + cellParsers[aboutIndex].getName() + "}" : null;
 
 		LOGGER.info("Parsing {}", csvFile);
 
@@ -382,14 +387,19 @@ private CSVReader getCSVReader(Model metadata, Resource table, Reader reader) {
 		Optional<Value> val = Models.getProperty(metadata, table, CSVW.DIALECT);
 		if (val.isPresent()) {
 			Resource dialect = (Resource) val.get();
+
+			// skip header (and possibly other) rows
+			String headerRows = Models.getPropertyString(metadata, dialect, CSVW.HEADER_ROW_COUNT).orElse("1");
+			String skipRows = Models.getPropertyString(metadata, dialect, CSVW.SKIP_ROWS).orElse("0");
+			int skip = Integer.valueOf(headerRows) + Integer.valueOf(skipRows);
+			Models.getPropertyString(metadata, dialect, CSVW.HEADER)
+					.ifPresent(v -> builder.withSkipLines(v.equalsIgnoreCase("false") ? 0 : skip));
+
 			Models.getPropertyString(metadata, dialect, CSVW.DELIMITER)
 					.ifPresent(v -> parserBuilder.withSeparator(v.charAt(0)));
-			Models.getPropertyString(metadata, dialect, CSVW.HEADER)
-					.ifPresent(v -> builder.withSkipLines(v.equalsIgnoreCase("false") ? 0 : 1));
 			Models.getPropertyString(metadata, dialect, CSVW.QUOTE_CHAR)
 					.ifPresent(v -> parserBuilder.withQuoteChar(v.charAt(0)));
 		}
-
 		return builder.withCSVParser(parserBuilder.build()).build();
 	}
 
@@ -423,7 +433,7 @@ private Resource getIRIorBnode(CellParser[] cellParsers, String[] cells, String
 		if (aboutIndex > -1) {
 			Value val = cellParsers[aboutIndex].parse(cells[aboutIndex]);
 			if (val != null) {
-				return Values.iri(aboutURL.replace(placeholder, val.toString()));
+				return Values.iri(aboutURL.replace(placeholder, val.stringValue()));
 			} else {
 				throw new RDFParseException("NULL value in aboutURL");
 			}

core/rio/csvw/src/main/java/org/eclipse/rdf4j/rio/csvw/parsers/CellParser.java

@@ -27,6 +27,7 @@ public abstract class CellParser {
 	protected String lang;
 	protected String defaultValue;
 	protected boolean isRequired;
+	protected boolean isVirtual;
 	protected IRI propertyIRI;
 	protected String valueUrl;
 	protected String format;
@@ -174,6 +175,20 @@ protected String getValueOrDefault(String s) {
 		return s;
 	}
 
+	/**
+	 * @return true if the column is virtual
+	 */
+	public boolean isVirtual() {
+		return this.isVirtual;
+	}
+
+	/**
+	 * @param isVirtual
+	 */
+	public void setVirtual(boolean isVirtual) {
+		this.isVirtual = isVirtual;
+	}
+
 	/**
 	 * Get the value from a cell
 	 *

core/rio/csvw/src/test/resources/painters-metadata.json

@@ -2,21 +2,23 @@
   "@context": "http://www.w3.org/ns/csvw",
   "url": "painters.csv",
   "tableSchema": {
+    "aboutUrl": "https://www.wikidata.org/wiki/{wikidata_id}",
     "columns": [
       { "name": "wikidata_id", 
-        "datatype": "string",
-        "valueUrl": "https://www.wikidata.org/wiki/{wikidata_id}"},
+        "datatype": "string"},
       { "name": "first_name",
         "propertyUrl": "schema:givenName"},
       { "name": "last_name",
         "propertyUrl": "schema:familyName"},
       { "name": "country_id",
+        "propertyUrl": "schema:nationality",
         "valueUrl": "https://www.wikidata.org/wiki/{country_id}"},
       { "name": "country_name_nl",
         "lang": "nl" },
       { "name": "country_name_en",
         "lang": "en" },
       { "name": "date_of_birth",
+        "propertyUrl": "schema:birthDate",
         "datatype": { 
            "base": "date", 
            "format": "d/M/yyyy"
@@ -27,7 +29,10 @@
             "format": "Yes|No"
         } },
       { "name": "languages",
-        "separator": " " }
+        "separator": " " },
+      { "virtual": true,
+        "propertyUrl": "rdf:type",
+        "valueUrl": "schema:Person" }
     ],
    "primaryKey": "wikidata_id"
   }