From f19a7a3d78f9dd3101fb4f390cfb44e1975f513c Mon Sep 17 00:00:00 2001
From: Even Rouault <even.rouault@spatialys.com>
Date: Wed, 4 Sep 2024 17:22:33 +0200
Subject: [PATCH 1/2] netCDF: make sure CreateMetadataFromOtherVars() doesn't
 set PAM dirty flag

---
 autotest/gdrivers/netcdf_multidim.py | 10 ++++++++++
 frmts/netcdf/netcdfdataset.cpp       |  3 +++
 2 files changed, 13 insertions(+)

diff --git a/autotest/gdrivers/netcdf_multidim.py b/autotest/gdrivers/netcdf_multidim.py
index c6134d376c07..a566cb900f3f 100755
--- a/autotest/gdrivers/netcdf_multidim.py
+++ b/autotest/gdrivers/netcdf_multidim.py
@@ -2096,6 +2096,9 @@ def test_netcdf_multidim_getcoordinatevariables():
 
 def test_netcdf_multidim_getresampled_with_geoloc():
 
+    if os.path.exists("data/netcdf/sentinel5p_fake.nc.aux.xml"):
+        os.unlink("data/netcdf/sentinel5p_fake.nc.aux.xml")
+
     ds = gdal.OpenEx("data/netcdf/sentinel5p_fake.nc", gdal.OF_MULTIDIM_RASTER)
     rg = ds.GetRootGroup()
 
@@ -2118,6 +2121,8 @@ def test_netcdf_multidim_getresampled_with_geoloc():
         warped_ds = gdal.Warp("", "data/netcdf/sentinel5p_fake.nc", format="MEM")
     assert warped_ds.ReadRaster() == resampled_ar.Read()
 
+    assert not os.path.exists("data/netcdf/sentinel5p_fake.nc.aux.xml")
+
 
 def test_netcdf_multidim_cache():
 
@@ -3575,6 +3580,9 @@ def reopen():
 
 def test_netcdf_multidim_getresampled_with_geoloc_EMIT_L2A():
 
+    if os.path.exists("data/netcdf/fake_EMIT_L2A.nc.aux.xml"):
+        os.unlink("data/netcdf/fake_EMIT_L2A.nc.aux.xml")
+
     ds = gdal.OpenEx("data/netcdf/fake_EMIT_L2A.nc", gdal.OF_MULTIDIM_RASTER)
     rg = ds.GetRootGroup()
 
@@ -3770,6 +3778,8 @@ def test_netcdf_multidim_getresampled_with_geoloc_EMIT_L2A():
         20.0,
     )
 
+    assert not os.path.exists("data/netcdf/fake_EMIT_L2A.nc.aux.xml")
+
 
 def test_netcdf_multidim_getresampled_with_geoloc_EMIT_L2A_with_good_wavelengths():
 
diff --git a/frmts/netcdf/netcdfdataset.cpp b/frmts/netcdf/netcdfdataset.cpp
index 343b30951285..e2dcce35dc6e 100644
--- a/frmts/netcdf/netcdfdataset.cpp
+++ b/frmts/netcdf/netcdfdataset.cpp
@@ -1965,6 +1965,7 @@ void netCDFRasterBand::CreateMetadataFromOtherVars()
     m_bCreateMetadataFromOtherVarsDone = true;
 
     netCDFDataset *l_poDS = reinterpret_cast<netCDFDataset *>(poDS);
+    const int nPamFlagsBackup = l_poDS->nPamFlags;
 
     // Compute all dimensions from Band number and save in Metadata.
     int nd = 0;
@@ -2134,6 +2135,8 @@ void netCDFRasterBand::CreateMetadataFromOtherVars()
 
         Taken += result * Sum;
     }  // End loop non-spatial dimensions.
+
+    l_poDS->nPamFlags = nPamFlagsBackup;
 }
 
 /************************************************************************/

From 4bb6d164867efb87a01183f0600423cc8f6e64c2 Mon Sep 17 00:00:00 2001
From: Even Rouault <even.rouault@spatialys.com>
Date: Wed, 4 Sep 2024 17:29:00 +0200
Subject: [PATCH 2/2] Multidim: AsClassicDataset(): make it able to retrieve
 dataset metadata from PAM

---
 autotest/gdrivers/netcdf_multidim.py | 43 ++++++++++++++++++++++++++++
 gcore/gdalmultidim.cpp               |  6 ++++
 2 files changed, 49 insertions(+)

diff --git a/autotest/gdrivers/netcdf_multidim.py b/autotest/gdrivers/netcdf_multidim.py
index a566cb900f3f..46c347a42d99 100755
--- a/autotest/gdrivers/netcdf_multidim.py
+++ b/autotest/gdrivers/netcdf_multidim.py
@@ -4126,3 +4126,46 @@ def test_netcdf_multidim_chunk_cache_options():
         "CHUNK_SLOTS": "1000",
         "PREEMPTION": "0.900000",
     }
+
+
+###############################################################################
+
+
+def test_netcdf_multidim_as_classic_dataset_metadata():
+    def set_metadata():
+        ds = gdal.OpenEx(
+            "data/netcdf/fake_EMIT_L2A_with_good_wavelengths.nc",
+            gdal.OF_MULTIDIM_RASTER,
+        )
+        rg = ds.GetRootGroup()
+        ar = rg.OpenMDArray("reflectance")
+        resampled_ar = ar.GetResampled(
+            [None, None, None], gdal.GRIORA_NearestNeighbour, None
+        )
+        assert resampled_ar is not None
+        classic_ds = ar.AsClassicDataset(1, 0)
+        classic_ds.SetMetadataItem("foo", "bar")
+
+    def check_metadata():
+        ds = gdal.OpenEx(
+            "data/netcdf/fake_EMIT_L2A_with_good_wavelengths.nc",
+            gdal.OF_MULTIDIM_RASTER,
+        )
+        rg = ds.GetRootGroup()
+        ar = rg.OpenMDArray("reflectance")
+        resampled_ar = ar.GetResampled(
+            [None, None, None], gdal.GRIORA_NearestNeighbour, None
+        )
+        assert resampled_ar is not None
+        classic_ds = ar.AsClassicDataset(1, 0)
+        assert classic_ds.GetMetadataItem("foo") == "bar"
+
+    pam_filename = "data/netcdf/fake_EMIT_L2A_with_good_wavelengths.nc.aux.xml"
+    if os.path.exists(pam_filename):
+        os.unlink(pam_filename)
+
+    set_metadata()
+    check_metadata()
+
+    assert os.path.exists(pam_filename)
+    os.unlink(pam_filename)
diff --git a/gcore/gdalmultidim.cpp b/gcore/gdalmultidim.cpp
index 3e344ae98623..b46bf17780fe 100644
--- a/gcore/gdalmultidim.cpp
+++ b/gcore/gdalmultidim.cpp
@@ -9500,6 +9500,12 @@ GDALDatasetFromArray *GDALDatasetFromArray::Create(
         }
         poDS->SetDerivedDatasetName(osDerivedDatasetName.c_str());
         poDS->TryLoadXML();
+
+        for (const auto &[pszKey, pszValue] : cpl::IterateNameValue(
+                 CSLConstList(poDS->GDALPamDataset::GetMetadata())))
+        {
+            poDS->m_oMDD.SetMetadataItem(pszKey, pszValue);
+        }
     }
 
     return poDS.release();