default value behaviour

src/data/attr.rs

@@ -136,7 +136,7 @@ impl AttributeTyping {
     fn type_err(&self, val: Value) -> TypeError {
         TypeError::Typing(*self, format!("{:?}", val))
     }
-    fn coerce_value<'a>(&self, val: Value<'a>) -> Result<Value<'a>> {
+    pub(crate) fn coerce_value<'a>(&self, val: Value<'a>) -> Result<Value<'a>> {
         match self {
             AttributeTyping::Ref | AttributeTyping::Component => match val {
                 val @ Value::EnId(_) => Ok(val),

src/preprocess/pull.rs

@@ -126,7 +126,7 @@ impl SessionTx {
                             JsonValue::Object(desc.clone()),
                             "expect boolean or number".to_string(),
                         )
-                            .into());
+                        .into());
                     }
                     recursive = true;
                 }
@@ -144,7 +144,7 @@ impl SessionTx {
                                 JsonValue::Object(desc.clone()),
                                 "expect array".to_string(),
                             )
-                                .into());
+                            .into());
                         }
                     };
                 }
@@ -153,7 +153,7 @@ impl SessionTx {
                         v.into(),
                         "unexpected spec key".to_string(),
                     )
-                        .into());
+                    .into());
                 }
             }
         }
@@ -169,7 +169,7 @@ impl SessionTx {
                 JsonValue::Object(desc.clone()),
                 "expect target key".to_string(),
             )
-                .into());
+            .into());
         }
 
         let input_kw = input_kw.unwrap();
@@ -188,6 +188,12 @@ impl SessionTx {
             recursion_depth = max(recursion_depth, 1);
         }
 
+        let default_val = if default_val == Value::Null {
+            default_val
+        } else {
+            attr.val_type.coerce_value(default_val)?
+        };
+
         Ok(PullSpec::Attr(AttrPullSpec {
             attr,
             default_val,

src/transact/pull.rs

@@ -152,7 +152,7 @@ impl SessionTx {
                     collector,
                     recursive_seen,
                 )?;
-            } else {
+            } else if spec.default_val != Value::Null {
                 self.pull_attr_collect(
                     spec,
                     spec.default_val.clone(),
@@ -372,7 +372,7 @@ impl SessionTx {
                     collector,
                     recursive_seen,
                 )?;
-            } else {
+            } else if spec.default_val != Value::Null {
                 self.pull_attr_collect(
                     spec,
                     spec.default_val.clone(),