Merge #264

264: Added wrapper for OGR_L_SetFeature r=rmanoka a=geohardtke

- [x] I agree to follow the project's [code of conduct](https://github.com/georust/gdal/blob/master/CODE_OF_CONDUCT.md).
- [x] I added an entry to `CHANGES.md` if knowledge of this change could be valuable to users.
---

Hi, I tried to find a way to update the value of a field in a vector and couldn't find a way to achieve that. Maybe I missed something? If so, sorry. Otherwise here is a pull request that implements a wrapper for OGR_L_SetFeature. 

It can be used as follows:

```rust
        let ds_options = DatasetOptions {
            open_flags: GdalOpenFlags::GDAL_OF_UPDATE,
            ..DatasetOptions::default()
        };
        let ds = Dataset::open_ex("three_layer_ds.s3db"), ds_options).unwrap();
        let mut layer = ds.layer(0).unwrap();
        let fids: Vec<u64> = layer.features().map(|f| f.fid().unwrap()).collect();
        let feature = layer.feature(fids[0]).unwrap();
        feature.set_field_integer("id", 1).ok();
        layer.set_feature(feature).ok();
 ```

Co-authored-by: Leonardo Hardtke <[email protected]>
Co-authored-by: geohardtke <[email protected]>

CHANGES.md

@@ -14,6 +14,10 @@
 
   - <https://github.com/georust/gdal/pull/251>
 
+- Implemented wrapper for `OGR_L_SetFeature`
+
+  - <https://github.com/georust/gdal/pull/264>
+
 - Add `programs::raster::build_vrt`
 - Add `GeoTransformEx` extension trait with `apply` and `invert`
 

src/vector/layer.rs

@@ -250,6 +250,13 @@ pub trait LayerAccess: Sized {
         FeatureIterator::_with_layer(self)
     }
 
+    /// Set a feature on this layer layer.
+    /// Refer[SetFeature](https://gdal.org/doxygen/classOGRLayer.html#a681139bfd585b74d7218e51a32144283)
+    fn set_feature(&self, feature: Feature) -> Result<()> {
+        unsafe { gdal_sys::OGR_L_SetFeature(self.c_layer(), feature.c_feature()) };
+        Ok(())
+    }
+
     /// Set a spatial filter on this layer.
     ///
     /// Refer [OGR_L_SetSpatialFilter](https://gdal.org/doxygen/classOGRLayer.html#a75c06b4993f8eb76b569f37365cd19ab)

src/vector/vector_tests/mod.rs

@@ -3,8 +3,7 @@ use super::{
     OGRwkbGeometryType, OwnedLayer,
 };
 use crate::spatial_ref::SpatialRef;
-use crate::{assert_almost_eq, Dataset, Driver};
-
+use crate::{assert_almost_eq, Dataset, DatasetOptions, Driver, GdalOpenFlags};
 mod convert_geo;
 mod sql;
 
@@ -815,4 +814,28 @@ mod tests {
             );
         });
     }
+
+    #[test]
+    fn test_set_feature() {
+        let ds_options = DatasetOptions {
+            open_flags: GdalOpenFlags::GDAL_OF_UPDATE,
+            ..DatasetOptions::default()
+        };
+        let tmp_file = "/tmp/test.s3db";
+        std::fs::copy(fixture!("three_layer_ds.s3db"), tmp_file).unwrap();
+        let ds = Dataset::open_ex(tmp_file, ds_options).unwrap();
+        let mut layer = ds.layer(0).unwrap();
+        let fids: Vec<u64> = layer.features().map(|f| f.fid().unwrap()).collect();
+        let feature = layer.feature(fids[0]).unwrap();
+        // to original value of the id field in fid 0 is null; we will set it to 1.
+        feature.set_field_integer("id", 1).ok();
+        layer.set_feature(feature).ok();
+
+        // now we check that the field is 1.
+        let ds = Dataset::open(tmp_file).unwrap();
+        let layer = ds.layer(0).unwrap();
+        let feature = layer.feature(fids[0]).unwrap();
+        let value = feature.field("id").unwrap().unwrap().into_int().unwrap();
+        assert_eq!(value, 1);
+    }
 }