From a3c2fb93809367bb162ec9ab2286e8a745e92f8f Mon Sep 17 00:00:00 2001
From: rossbowen <ross.bowen@ons.gov.uk>
Date: Fri, 21 Jan 2022 10:24:18 +0000
Subject: [PATCH] Stop emitting triple when cell is null and valueUrl is
 present #45

---
 lib/metadata/TableSchema.js                   | 17 ++++++++--------
 test/support/test031-null-cell.csv            |  3 +++
 .../test031-null-cell.csv-metadata.json       | 20 +++++++++++++++++++
 test/support/test031-null-cell.nt             | 17 ++++++++++++++++
 4 files changed, 49 insertions(+), 8 deletions(-)
 create mode 100644 test/support/test031-null-cell.csv
 create mode 100644 test/support/test031-null-cell.csv-metadata.json
 create mode 100644 test/support/test031-null-cell.nt

diff --git a/lib/metadata/TableSchema.js b/lib/metadata/TableSchema.js
index 141cf94..5d95898 100644
--- a/lib/metadata/TableSchema.js
+++ b/lib/metadata/TableSchema.js
@@ -144,20 +144,21 @@ class TableSchema {
       return undefined
     }
 
-    if (column.valueUrl) {
-      return this.factory.namedNode(column.valueUrl.fill(row))
-    }
-
     let value = column.titles.reduce((value, title) => {
       return value || row[title]
     }, '')
 
-    if (value === '') {
-      value = column.defaultValue
+    if (!column.virtual) {
+      if (value === '') {
+        value = column.defaultValue
+      }
+      if (typeof value === 'undefined' || value === column.nullValue) {
+        return undefined
+      }
     }
 
-    if (typeof value === 'undefined' || value === column.nullValue) {
-      return undefined
+    if (column.valueUrl) {
+      return this.factory.namedNode(column.valueUrl.fill(row))
     }
 
     if (column.datatype.base.value === this.ns.dateTime.value) {
diff --git a/test/support/test031-null-cell.csv b/test/support/test031-null-cell.csv
new file mode 100644
index 0000000..97d95ad
--- /dev/null
+++ b/test/support/test031-null-cell.csv
@@ -0,0 +1,3 @@
+a,b
+100,200
+300,
diff --git a/test/support/test031-null-cell.csv-metadata.json b/test/support/test031-null-cell.csv-metadata.json
new file mode 100644
index 0000000..d7240e0
--- /dev/null
+++ b/test/support/test031-null-cell.csv-metadata.json
@@ -0,0 +1,20 @@
+{
+    "@context": "http://www.w3.org/ns/csvw",
+    "url": "nulls.csv",
+    "tableSchema": {
+        "columns": [
+            {
+                "titles": "a",
+                "name": "a",
+                "propertyUrl": "http://example.org/a",
+                "valueUrl": "http://example.org/{a}"
+            },
+            {
+                "titles": "b",
+                "name": "b",
+                "propertyUrl": "http://example.org/b",
+                "valueUrl": "http://example.org/{b}"
+            }
+        ]
+    }
+}
\ No newline at end of file
diff --git a/test/support/test031-null-cell.nt b/test/support/test031-null-cell.nt
new file mode 100644
index 0000000..8dc29fa
--- /dev/null
+++ b/test/support/test031-null-cell.nt
@@ -0,0 +1,17 @@
+_:c14n0 <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> <http://www.w3.org/ns/csvw#Row> .
+_:c14n0 <http://www.w3.org/ns/csvw#describes> _:c14n3 .
+_:c14n0 <http://www.w3.org/ns/csvw#rownum> "1"^^<http://www.w3.org/2001/XMLSchema#integer> .
+_:c14n0 <http://www.w3.org/ns/csvw#url> <test031-null-cell.csv#row=2> .
+_:c14n1 <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> <http://www.w3.org/ns/csvw#Table> .
+_:c14n1 <http://www.w3.org/ns/csvw#row> _:c14n0 .
+_:c14n1 <http://www.w3.org/ns/csvw#row> _:c14n5 .
+_:c14n1 <http://www.w3.org/ns/csvw#url> <test031-null-cell.csv> .
+_:c14n2 <http://example.org/a> <http://example.org/300> .
+_:c14n3 <http://example.org/a> <http://example.org/100> .
+_:c14n3 <http://example.org/b> <http://example.org/200> .
+_:c14n4 <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> <http://www.w3.org/ns/csvw#TableGroup> .
+_:c14n4 <http://www.w3.org/ns/csvw#table> _:c14n1 .
+_:c14n5 <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> <http://www.w3.org/ns/csvw#Row> .
+_:c14n5 <http://www.w3.org/ns/csvw#describes> _:c14n2 .
+_:c14n5 <http://www.w3.org/ns/csvw#rownum> "2"^^<http://www.w3.org/2001/XMLSchema#integer> .
+_:c14n5 <http://www.w3.org/ns/csvw#url> <test031-null-cell.csv#row=3> .
\ No newline at end of file