feat: add required argument to taxonomy functions (#1598)

components/templates/src/global_fns/content.rs

@@ -40,10 +40,17 @@ impl TeraFn for GetTaxonomyUrl {
         let lang =
             optional_arg!(String, args.get("lang"), "`get_taxonomy`: `lang` must be a string")
                 .unwrap_or_else(|| self.default_lang.clone());
+        let required = optional_arg!(
+            bool,
+            args.get("required"),
+            "`get_taxonomy_url`: `required` must be a boolean (true or false)"
+        )
+        .unwrap_or(true);
 
-        let container = match self.taxonomies.get(&format!("{}-{}", kind, lang)) {
-            Some(c) => c,
-            None => {
+        let container = match (self.taxonomies.get(&format!("{}-{}", kind, lang)), required) {
+            (Some(c), _) => c,
+            (None, false) => return Ok(Value::Null),
+            (None, true) => {
                 return Err(format!(
                     "`get_taxonomy_url` received an unknown taxonomy as kind: {}",
                     kind
@@ -154,14 +161,21 @@ impl TeraFn for GetTaxonomy {
             args.get("kind"),
             "`get_taxonomy` requires a `kind` argument with a string value"
         );
+        let required = optional_arg!(
+            bool,
+            args.get("required"),
+            "`get_taxonomy`: `required` must be a boolean (true or false)"
+        )
+        .unwrap_or(true);
 
         let lang =
             optional_arg!(String, args.get("lang"), "`get_taxonomy`: `lang` must be a string")
                 .unwrap_or_else(|| self.default_lang.clone());
 
-        match self.taxonomies.get(&format!("{}-{}", kind, lang)) {
-            Some(t) => Ok(to_value(t.to_serialized(&self.library.read().unwrap())).unwrap()),
-            None => {
+        match (self.taxonomies.get(&format!("{}-{}", kind, lang)), required) {
+            (Some(t), _) => Ok(to_value(t.to_serialized(&self.library.read().unwrap())).unwrap()),
+            (None, false) => Ok(Value::Null),
+            (None, true) => {
                 Err(format!("`get_taxonomy` received an unknown taxonomy as kind: {}", kind).into())
             }
         }

docs/content/documentation/templates/overview.md

@@ -156,6 +156,8 @@ the value should be the same as the one in the front matter, not the slugified v
 
 `lang` (optional) default to `config.default_language` in config.toml
 
+`required` (optional) if a taxonomy is defined but there isn't any content that uses it then throw an error. Defaults to true.
+
 ### `get_taxonomy`
 Gets the whole taxonomy of a specific kind.
 
@@ -172,6 +174,8 @@ items: Array<TaxonomyTerm>;
 
 `lang` (optional) default to `config.default_language` in config.toml
 
+`required` (optional) if a taxonomy is defined but there isn't any content that uses it then throw an error. Defaults to true.
+
 See the [Taxonomies documentation](@/documentation/templates/taxonomies.md) for a full documentation of those types.
 
 ### `get_url`