fix(core): don't add bands if they're all empty

Author: gadomski

core/CHANGELOG.md

@@ -14,6 +14,10 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 - Experimental GeoParquet and GeoArrow support ([#316](https://github.com/stac-utils/stac-rs/pull/316), [#319](https://github.com/stac-utils/stac-rs/pull/319), [#328](https://github.com/stac-utils/stac-rs/pull/328))
 - Public `stac::io` module ([#319](https://github.com/stac-utils/stac-rs/pull/319))
 
+### Fixed
+
+- Don't add a `bands` attribute if all bands are empty when migrating ([#351](https://github.com/stac-utils/stac-rs/pull/351))
+
 ### Changed
 
 - Use `DateTime<Utc>` instead of `String` for datetimes ([#297](https://github.com/stac-utils/stac-rs/pull/297), [#304](https://github.com/stac-utils/stac-rs/pull/304))

core/data/20201211_223832_CS2.json

@@ -0,0 +1,101 @@
+{
+  "type": "Feature",
+  "stac_version": "1.0.0",
+  "stac_extensions": [
+    "https://stac-extensions.github.io/projection/v1.1.0/schema.json",
+    "https://stac-extensions.github.io/raster/v1.1.0/schema.json"
+  ],
+  "id": "20201211_223832_CS2",
+  "geometry": {
+    "type": "Polygon",
+    "coordinates": [
+      [
+        [
+          172.9117367,
+          1.3438852
+        ],
+        [
+          172.9546961,
+          1.3438852
+        ],
+        [
+          172.9546961,
+          90.0
+        ],
+        [
+          172.9117367,
+          90.0
+        ],
+        [
+          172.9117367,
+          1.3438852
+        ]
+      ]
+    ],
+    "bbox": [
+      172.9117367,
+      1.3438852,
+      172.9546961,
+      90.0
+    ]
+  },
+  "bbox": [
+    172.9117367,
+    1.3438852,
+    172.9546961,
+    90.0
+  ],
+  "properties": {
+    "datetime": "2024-09-05T22:33:45.900997Z",
+    "proj:epsg": 32659,
+    "proj:bbox": [
+      712710.0,
+      148627.0,
+      717489.5,
+      151406.0
+    ],
+    "proj:centroid": {
+      "lat": 1.3564664,
+      "lon": 172.9332164
+    },
+    "proj:shape": [
+      5558,
+      9559
+    ],
+    "proj:transform": [
+      0.5,
+      0.0,
+      712710.0,
+      0.0,
+      -0.5,
+      151406.0
+    ]
+  },
+  "links": [],
+  "assets": {
+    "data": {
+      "href": "/Users/gadomski/Downloads/20201211_223832_CS2.tif",
+      "roles": [
+        "data"
+      ],
+      "raster:bands": [
+        {
+          "data_type": "uint8",
+          "spatial_resolution": 0.5
+        },
+        {
+          "data_type": "uint8",
+          "spatial_resolution": 0.5
+        },
+        {
+          "data_type": "uint8",
+          "spatial_resolution": 0.5
+        },
+        {
+          "data_type": "uint8",
+          "spatial_resolution": 0.5
+        }
+      ]
+    }
+  }
+}

core/src/migrate.rs

@@ -164,10 +164,12 @@ fn migrate_bands(asset: &mut Map<String, Value>) -> Result<()> {
             }
         }
     }
-    let _ = asset.insert(
-        "bands".into(),
-        Value::Array(bands.into_iter().map(Value::Object).collect()),
-    );
+    if bands.iter().any(|band| !band.is_empty()) {
+        let _ = asset.insert(
+            "bands".into(),
+            Value::Array(bands.into_iter().map(Value::Object).collect()),
+        );
+    }
     Ok(())
 }
 
@@ -235,4 +237,13 @@ mod tests {
         let item = item.migrate(Version::v1_1_0_beta_1).unwrap();
         assert_eq!(item.link("self").unwrap().href, "file:///an/absolute/href");
     }
+
+    #[test]
+    fn remove_empty_bands() {
+        // https://github.com/stac-utils/stac-rs/issues/350
+        let item: Item = crate::read("data/20201211_223832_CS2.json").unwrap();
+        let item = item.migrate(Version::v1_1_0_beta_1).unwrap();
+        let asset = &item.assets["data"];
+        assert!(asset.bands.is_empty());
+    }
 }