Filter default properties in json middlewares instead of filter fn

rojo-test/syncback-test-snapshots/end_to_end__rojo_test__syncback_util__all_middleware.snap

@@ -11,15 +11,19 @@ added_files:
   - src/dir/init_server_script/init.server.luau
   - src/dir/module_script.luau
   - src/dir/server_script.server.luau
+  - src/dir_with_meta/init.meta.json
   - src/model_json.model.json
   - src/project_json.project.json
   - src/rbxm.rbxm
   - src/rbxmx.rbxmx
   - src/text.txt
 added_dirs:
+  - src
   - src/csv_init
+  - src/dir
   - src/dir/init_client_script
   - src/dir/init_module_script
   - src/dir/init_server_script
+  - src/dir_with_meta
 removed_files: []
 removed_dirs: []

rojo-test/syncback-test-snapshots/end_to_end__rojo_test__syncback_util__child_but_not.snap

@@ -5,6 +5,8 @@ expression: "visualize_fs_snapshot(&fs_snapshot, &output_path)"
 added_files:
   - OnlyOneCopy/child_of_one.luau
   - ReplicatedStorage/child_replicated_storage.luau
-added_dirs: []
+added_dirs:
+  - OnlyOneCopy
+  - ReplicatedStorage
 removed_files: []
 removed_dirs: []

rojo-test/syncback-test-snapshots/end_to_end__rojo_test__syncback_util__ignore_paths_removing.snap

@@ -1,9 +1,9 @@
 ---
 source: tests/rojo_test/syncback_util.rs
-assertion_line: 48
 expression: "visualize_fs_snapshot(&fs_snapshot, &output_path)"
 ---
-added_files: []
+added_files:
+  - default.project.json
 added_dirs:
   - src
 removed_files: []

rojo-test/syncback-test-snapshots/end_to_end__rojo_test__syncback_util__ignore_trees.snap

@@ -5,6 +5,7 @@ expression: "visualize_fs_snapshot(&fs_snapshot, &output_path)"
 added_files:
   - src/IncludeMe/.gitkeep
 added_dirs:
+  - src
   - src/IncludeMe
 removed_files: []
 removed_dirs: []

rojo-test/syncback-test-snapshots/end_to_end__rojo_test__syncback_util__nested_projects_weird.snap

@@ -5,6 +5,7 @@ expression: "visualize_fs_snapshot(&fs_snapshot, &output_path)"
 added_files:
   - src/modules/ClientModule.luau
   - src/modules/ServerModule.luau
-added_dirs: []
+added_dirs:
+  - src/modules
 removed_files: []
 removed_dirs: []

rojo-test/syncback-test-snapshots/end_to_end__rojo_test__syncback_util__project_all_middleware.snap

@@ -3,6 +3,7 @@ source: tests/rojo_test/syncback_util.rs
 expression: "visualize_fs_snapshot(&fs_snapshot, &output_path)"
 ---
 added_files:
+  - default.project.json
   - src/client_script.client.luau
   - src/csv.csv
   - src/csv_init/init.csv
@@ -17,6 +18,8 @@ added_files:
   - src/text.txt
 added_dirs:
   - src/csv_init
+  - src/dir
+  - src/dir_with_meta
   - src/init_client_script
   - src/init_module_script
   - src/init_server_script

rojo-test/syncback-test-snapshots/end_to_end__rojo_test__syncback_util__project_init.snap

@@ -3,6 +3,7 @@ source: tests/rojo_test/syncback_util.rs
 expression: "visualize_fs_snapshot(&fs_snapshot, &output_path)"
 ---
 added_files:
+  - default.project.json
   - src/init.luau
 added_dirs:
   - src

rojo-test/syncback-test-snapshots/end_to_end__rojo_test__syncback_util__project_reserialize.snap

@@ -4,6 +4,7 @@ expression: "visualize_fs_snapshot(&fs_snapshot, &output_path)"
 ---
 added_files:
   - attribute_mismatch.luau
+  - default.project.json
   - property_mismatch.project.json
 added_dirs: []
 removed_files: []

rojo-test/syncback-test-snapshots/end_to_end__rojo_test__syncback_util__rbxm_fallback.snap

@@ -6,6 +6,7 @@ added_files:
   - ReplicatedStorage/ChildWithDuplicates.rbxm
   - ReplicatedStorage/ChildWithoutDuplicates/Child/.gitkeep
 added_dirs:
+  - ReplicatedStorage
   - ReplicatedStorage/ChildWithoutDuplicates
   - ReplicatedStorage/ChildWithoutDuplicates/Child
 removed_files: []

rojo-test/syncback-test-snapshots/end_to_end__rojo_test__syncback_util__ref_properties.snap

@@ -5,6 +5,7 @@ expression: "visualize_fs_snapshot(&fs_snapshot, &output_path)"
 added_files:
   - src/pointer.model.json
   - src/target.model.json
-added_dirs: []
+added_dirs:
+  - src
 removed_files: []
 removed_dirs: []

rojo-test/syncback-test-snapshots/end_to_end__rojo_test__syncback_util__ref_properties_update.snap

@@ -5,6 +5,7 @@ expression: "visualize_fs_snapshot(&fs_snapshot, &output_path)"
 added_files:
   - src/pointer.model.json
   - src/target.model.json
-added_dirs: []
+added_dirs:
+  - src
 removed_files: []
 removed_dirs: []

src/snapshot_middleware/json_model.rs

@@ -17,6 +17,8 @@ use crate::{
     RojoRef,
 };
 
+use super::filter_default_property;
+
 pub fn snapshot_json_model(
     context: &InstanceContext,
     vfs: &Vfs,
@@ -97,32 +99,14 @@ fn json_model_from_pair<'sync>(
     let mut properties = BTreeMap::new();
     let mut attributes = BTreeMap::new();
     for (name, value) in prop_buffer.drain(..) {
-        match value {
-            Variant::Attributes(attrs) => {
-                for (attr_name, attr_value) in attrs.iter() {
-                    // We (probably) don't want to preserve internal attributes,
-                    // only user defined ones.
-                    if attr_name.starts_with("RBX") {
-                        continue;
-                    }
-                    attributes.insert(
-                        attr_name.clone(),
-                        UnresolvedValue::from_variant_unambiguous(attr_value.clone()),
-                    );
-                }
-            }
-            Variant::SharedString(_) => {
-                log::warn!(
-                "Rojo cannot serialize the property {}.{name} in model.json files.\n\
-                If this is not acceptable, resave the Instance at '{}' manually as an RBXM or RBXMX.", new_inst.class, snapshot.get_new_inst_path(new))
-            }
-            _ => {
-                properties.insert(
-                    name.to_owned(),
-                    UnresolvedValue::from_variant(value.clone(), &new_inst.class, name),
-                );
-            }
-        }
+        filter_default_property(
+            snapshot,
+            new_inst,
+            name,
+            value,
+            &mut attributes,
+            &mut properties,
+        )
     }
 
     let mut children = Vec::with_capacity(new_inst.children().len());

src/snapshot_middleware/meta_file.rs

@@ -6,13 +6,15 @@ use std::{
 
 use anyhow::{format_err, Context};
 use memofs::{IoResultExt as _, Vfs};
-use rbx_dom_weak::types::{Attributes, Variant};
+use rbx_dom_weak::types::Attributes;
 use serde::{Deserialize, Serialize};
 
 use crate::{
     resolution::UnresolvedValue, snapshot::InstanceSnapshot, syncback::SyncbackSnapshot, RojoRef,
 };
 
+use super::filter_default_property;
+
 /// Represents metadata in a sibling file with the same basename.
 ///
 /// As an example, hello.meta.json next to hello.lua would allow assigning
@@ -80,34 +82,15 @@ impl AdjacentMetadata {
             .map(|inst| inst.metadata().ignore_unknown_instances)
             .unwrap_or_default();
 
-        let class = &snapshot.new_inst().class;
         for (name, value) in snapshot.get_path_filtered_properties(snapshot.new).unwrap() {
-            match value {
-                Variant::Attributes(attrs) => {
-                    for (attr_name, attr_value) in attrs.iter() {
-                        // We (probably) don't want to preserve internal
-                        // attributes, only user defined ones.
-                        if attr_name.starts_with("RBX") {
-                            continue;
-                        }
-                        attributes.insert(
-                            attr_name.clone(),
-                            UnresolvedValue::from_variant_unambiguous(attr_value.clone()),
-                        );
-                    }
-                }
-                Variant::SharedString(_) => {
-                    log::warn!(
-                    "Rojo cannot serialize the property {}.{name} in meta.json files.\n\
-                    If this is not acceptable, resave the Instance at '{}' manually as an RBXM or RBXMX.", class, snapshot.get_new_inst_path(snapshot.new))
-                }
-                _ => {
-                    properties.insert(
-                        name.to_owned(),
-                        UnresolvedValue::from_variant(value.clone(), class, name),
-                    );
-                }
-            }
+            filter_default_property(
+                snapshot,
+                snapshot.new_inst(),
+                name,
+                value,
+                &mut attributes,
+                &mut properties,
+            );
         }
 
         Ok(Some(Self {
@@ -266,34 +249,15 @@ impl DirectoryMetadata {
             .map(|inst| inst.metadata().ignore_unknown_instances)
             .unwrap_or_default();
 
-        let class = &snapshot.new_inst().class;
         for (name, value) in snapshot.get_path_filtered_properties(snapshot.new).unwrap() {
-            match value {
-                Variant::Attributes(attrs) => {
-                    for (name, value) in attrs.iter() {
-                        // We (probably) don't want to preserve internal
-                        // attributes, only user defined ones.
-                        if name.starts_with("RBX") {
-                            continue;
-                        }
-                        attributes.insert(
-                            name.to_owned(),
-                            UnresolvedValue::from_variant_unambiguous(value.clone()),
-                        );
-                    }
-                }
-                Variant::SharedString(_) => {
-                    log::warn!(
-                    "Rojo cannot serialize the property {}.{name} in meta.json files.\n\
-                    If this is not acceptable, resave the Instance at '{}' manually as an RBXM or RBXMX.", class, snapshot.get_new_inst_path(snapshot.new))
-                }
-                _ => {
-                    properties.insert(
-                        name.to_owned(),
-                        UnresolvedValue::from_variant(value.clone(), class, name),
-                    );
-                }
-            }
+            filter_default_property(
+                snapshot,
+                snapshot.new_inst(),
+                name,
+                value,
+                &mut attributes,
+                &mut properties,
+            )
         }
 
         Ok(Some(Self {

src/snapshot_middleware/mod.rs

@@ -19,17 +19,21 @@ mod txt;
 mod util;
 
 use std::{
+    collections::BTreeMap,
     path::{Path, PathBuf},
     sync::OnceLock,
 };
 
 use anyhow::Context;
 use memofs::{IoResultExt, Vfs};
+use rbx_dom_weak::{types::Variant, Instance};
 use serde::{Deserialize, Serialize};
 
 use crate::{
     glob::Glob,
+    resolution::UnresolvedValue,
     syncback::{SyncbackReturn, SyncbackSnapshot},
+    variant_eq::variant_eq,
 };
 use crate::{
     snapshot::{InstanceContext, InstanceSnapshot, SyncRule},
@@ -388,3 +392,58 @@ pub fn default_sync_rules() -> &'static [SyncRule] {
         ]
     })
 }
+
+fn filter_default_property(
+    snapshot: &SyncbackSnapshot,
+    new_inst: &Instance,
+    name: &str,
+    value: &Variant,
+    attributes: &mut BTreeMap<String, UnresolvedValue>,
+    properties: &mut BTreeMap<String, UnresolvedValue>,
+) {
+    let db = rbx_reflection_database::get();
+    let class_descriptor = db.classes.get(new_inst.class.as_str());
+
+    match value {
+        Variant::Attributes(attrs) => {
+            for (attr_name, attr_value) in attrs.iter() {
+                // We (probably) don't want to preserve internal attributes,
+                // only user defined ones.
+                if attr_name.starts_with("RBX") {
+                    continue;
+                }
+                attributes.insert(
+                    attr_name.clone(),
+                    UnresolvedValue::from_variant_unambiguous(attr_value.clone()),
+                );
+            }
+        }
+        Variant::SharedString(_) => {
+            log::warn!(
+                "Rojo cannot serialize the property {}.{name} in JSON files.\n\
+                 If this is not acceptable, resave the Instance at '{}' manually as an RBXM or RBXMX.",
+                new_inst.class, snapshot.get_new_inst_path(new_inst.referent())
+            )
+        }
+        _ => {
+            let new_prop_is_default = if let Some(class_descriptor) = class_descriptor {
+                if let Some(default) = db.find_default_property(class_descriptor, name) {
+                    variant_eq(value, default)
+                } else {
+                    false
+                }
+            } else {
+                false
+            };
+
+            if new_prop_is_default {
+                properties.remove(name);
+            } else {
+                properties.insert(
+                    name.to_owned(),
+                    UnresolvedValue::from_variant(value.clone(), &new_inst.class, name),
+                );
+            }
+        }
+    }
+}