From 4b5d1efe501e39240fcdaae5e7b8ef62fc7023df Mon Sep 17 00:00:00 2001
From: Even Rouault <even.rouault@spatialys.com>
Date: Sun, 5 Jun 2022 18:18:27 +0200
Subject: [PATCH] PROJJSON parser: do not error out if a datum ensemble member
 is unknown in the database

Fix issue raised in https://github.com/opengeospatial/geoparquet/discussions/110
---
 src/iso19111/io.cpp   | 34 +++++++++++++++++++++-------------
 test/unit/test_io.cpp | 14 ++++++++++++++
 2 files changed, 35 insertions(+), 13 deletions(-)

diff --git a/src/iso19111/io.cpp b/src/iso19111/io.cpp
index 72430a1789..f951470b33 100644
--- a/src/iso19111/io.cpp
+++ b/src/iso19111/io.cpp
@@ -6328,6 +6328,7 @@ DatumEnsembleNNPtr JSONParser::buildDatumEnsemble(const json &j) {
                 "Unexpected type for value of a \"members\" member");
         }
         auto datumName(getName(memberJ));
+        bool datumAdded = false;
         if (dbContext_ && memberJ.contains("id")) {
             auto id = getObject(memberJ, "id");
             auto authority = getString(id, "authority");
@@ -6344,11 +6345,16 @@ DatumEnsembleNNPtr JSONParser::buildDatumEnsemble(const json &j) {
             }
             try {
                 datums.push_back(authFactory->createDatum(codeStr));
+                datumAdded = true;
             } catch (const std::exception &) {
-                throw ParsingException("No Datum of code " + codeStr);
+                // Silently ignore, as this isn't necessary an error.
+                // If an older PROJ version parses a DatumEnsemble object of
+                // a more recent PROJ version where the datum ensemble got
+                // a new member, it might be unknown from the older PROJ.
             }
-            continue;
-        } else if (dbContext_) {
+        }
+
+        if (dbContext_ && !datumAdded) {
             auto authFactory = AuthorityFactory::create(NN_NO_CHECK(dbContext_),
                                                         std::string());
             auto list = authFactory->createObjectsFromName(
@@ -6360,19 +6366,21 @@ DatumEnsembleNNPtr JSONParser::buildDatumEnsemble(const json &j) {
                     throw ParsingException(
                         "DatumEnsemble member is not a datum");
                 datums.push_back(NN_NO_CHECK(datum));
-                continue;
+                datumAdded = true;
             }
         }
 
-        // Fallback if no db match
-        if (hasEllipsoid) {
-            datums.emplace_back(GeodeticReferenceFrame::create(
-                buildProperties(memberJ),
-                buildEllipsoid(getObject(j, "ellipsoid")),
-                optional<std::string>(), PrimeMeridian::GREENWICH));
-        } else {
-            datums.emplace_back(
-                VerticalReferenceFrame::create(buildProperties(memberJ)));
+        if (!datumAdded) {
+            // Fallback if no db match
+            if (hasEllipsoid) {
+                datums.emplace_back(GeodeticReferenceFrame::create(
+                    buildProperties(memberJ),
+                    buildEllipsoid(getObject(j, "ellipsoid")),
+                    optional<std::string>(), PrimeMeridian::GREENWICH));
+            } else {
+                datums.emplace_back(
+                    VerticalReferenceFrame::create(buildProperties(memberJ)));
+            }
         }
     }
     return DatumEnsemble::create(
diff --git a/test/unit/test_io.cpp b/test/unit/test_io.cpp
index 73b5e436be..27387be4a7 100644
--- a/test/unit/test_io.cpp
+++ b/test/unit/test_io.cpp
@@ -13809,6 +13809,13 @@ TEST(json_import, geographic_crs_with_datum_ensemble) {
                 "      },\n"
                 "      {\n"
                 "        \"name\": \"World Geodetic System 1984 (G730)\"\n"
+                "      },\n"
+                "      {\n"
+                "        \"name\": \"Some unknown ensemble with unknown id\",\n"
+                "        \"id\": {\n"
+                "          \"authority\": \"UNKNOWN\",\n"
+                "          \"code\": 1234\n"
+                "        }\n"
                 "      }\n"
                 "    ],\n"
                 "    \"ellipsoid\": {\n"
@@ -13858,6 +13865,13 @@ TEST(json_import, geographic_crs_with_datum_ensemble) {
         "          \"authority\": \"EPSG\",\n"
         "          \"code\": 1152\n"
         "        }\n"
+        "      },\n"
+        "      {\n"
+        "        \"name\": \"Some unknown ensemble with unknown id\",\n"
+        "        \"id\": {\n"
+        "          \"authority\": \"UNKNOWN\",\n"
+        "          \"code\": 1234\n"
+        "        }\n"
         "      }\n"
         "    ],\n"
         "    \"ellipsoid\": {\n"