fix: skip serializing if Option is None (#6)

Author: Stepan Kuzmin

src/tilejson.rs

@@ -11,16 +11,19 @@ pub struct TileJSON {
   pub tilejson: &'static str,
 
   /// The tileset id.
+  #[serde(skip_serializing_if = "Option::is_none")]
   pub id: Option<String>,
 
   /// A name describing the tileset. The name can
   /// contain any legal character. Implementations SHOULD NOT interpret the
   /// name as HTML.
+  #[serde(skip_serializing_if = "Option::is_none")]
   pub name: Option<String>,
 
   /// A text description of the tileset. The
   /// description can contain any legal character. Implementations SHOULD NOT
   /// interpret the description as HTML.
+  #[serde(skip_serializing_if = "Option::is_none")]
   pub description: Option<String>,
 
   /// A semver.org style version number. When
@@ -30,29 +33,34 @@ pub struct TileJSON {
   /// level MUST only have changes to tiles that are contained within one tile.
   /// When tiles change significantly, the major version MUST be increased.
   /// Implementations MUST NOT use tiles with different major versions.
+  #[serde(skip_serializing_if = "Option::is_none")]
   pub version: Option<String>,
 
   /// Contains an attribution to be displayed
   /// when the map is shown to a user. Implementations MAY decide to treat this
   /// as HTML or literal text. For security reasons, make absolutely sure that
   /// this field can't be abused as a vector for XSS or beacon tracking.
+  #[serde(skip_serializing_if = "Option::is_none")]
   pub attribution: Option<String>,
 
   /// Contains a mustache template to be used to
   /// format data from grids for interaction.
   /// See https://github.com/mapbox/utfgrid-spec/tree/master/1.2
   /// for the interactivity specification.
+  #[serde(skip_serializing_if = "Option::is_none")]
   pub template: Option<String>,
 
   /// Contains a legend to be displayed with the map.
   /// Implementations MAY decide to treat this as HTML or literal text.
   /// For security reasons, make absolutely sure that this field can't be
   /// abused as a vector for XSS or beacon tracking.
+  #[serde(skip_serializing_if = "Option::is_none")]
   pub legend: Option<String>,
 
   /// Either "xyz" or "tms". Influences the y
   /// direction of the tile coordinates.
   /// The global-mercator (aka Spherical Mercator) profile is assumed.
+  #[serde(skip_serializing_if = "Option::is_none")]
   pub scheme: Option<String>,
 
   /// An array of tile endpoints. {z}, {x} and {y}, if present,
@@ -69,6 +77,7 @@ pub struct TileJSON {
   /// for this tileset.
   /// See https://github.com/mapbox/utfgrid-spec/tree/master/1.2
   /// for the interactivity specification.
+  #[serde(skip_serializing_if = "Option::is_none")]
   pub grids: Option<Vec<String>>,
 
   /// An array of data files in GeoJSON format.
@@ -78,18 +87,22 @@ pub struct TileJSON {
   /// All endpoints MUST return the same content for the same URL.
   /// If the array doesn't contain any entries, then no data is present in
   /// the map.
+  #[serde(skip_serializing_if = "Option::is_none")]
   pub data: Option<Vec<String>>,
 
   /// An integer specifying the minimum zoom level.
+  #[serde(skip_serializing_if = "Option::is_none")]
   pub minzoom: Option<u8>,
 
   /// An integer specifying the maximum zoom level. MUST be >= minzoom.
+  #[serde(skip_serializing_if = "Option::is_none")]
   pub maxzoom: Option<u8>,
 
   /// The maximum extent of available map tiles. Bounds MUST define an area
   /// covered by all zoom levels. The bounds are represented in WGS:84
   /// latitude and longitude values, in the order left, bottom, right, top.
   /// Values may be integers or floating point numbers.
+  #[serde(skip_serializing_if = "Option::is_none")]
   pub bounds: Option<Vec<f32>>,
 
   /// The first value is the longitude, the second is latitude (both in
@@ -99,6 +112,7 @@ pub struct TileJSON {
   /// Implementations can use this value to set the default location. If the
   /// value is null, implementations may use their own algorithm for
   /// determining a default location.
+  #[serde(skip_serializing_if = "Option::is_none")]
   pub center: Option<Vec<i32>>,
 }
 
@@ -130,7 +144,7 @@ impl TileJSONBuilder {
       name: None,
       description: None,
       version: Some("1.0.0".to_owned()),
-      attribution:  Some("".to_string()),
+      attribution: None,
       template: None,
       legend: None,
       scheme: Some("xyz".to_owned()),
@@ -299,7 +313,7 @@ mod tests {
 
     assert_eq!(
       serialized_tilejson,
-      r#"{"tilejson":"2.2.0","id":null,"name":"compositing","description":null,"version":"1.0.0","attribution":"","template":null,"legend":null,"scheme":"tms","tiles":["http://localhost:8888/admin/1.0.0/world-light,broadband/{z}/{x}/{y}.png"],"grids":null,"data":null,"minzoom":0,"maxzoom":30,"bounds":[-180.0,-90.0,180.0,90.0],"center":null}"#
+      r#"{"tilejson":"2.2.0","name":"compositing","version":"1.0.0","scheme":"tms","tiles":["http://localhost:8888/admin/1.0.0/world-light,broadband/{z}/{x}/{y}.png"],"minzoom":0,"maxzoom":30,"bounds":[-180.0,-90.0,180.0,90.0]}"#
     )
   }
 }