address review comments

test/src/unit-current-domain-rest.cc

@@ -41,7 +41,8 @@ using namespace tiledb::test;
 struct RestCurrentDomainFx {
   RestCurrentDomainFx();
 
-  void create_sparse_array(const std::string& array_name);
+  void create_sparse_array(
+      const std::string& array_name, bool empty_ndr = false);
 
   VFSTestSetup vfs_test_setup_;
 
@@ -54,7 +55,8 @@ RestCurrentDomainFx::RestCurrentDomainFx()
     : ctx_c_(vfs_test_setup_.ctx_c) {
 }
 
-void RestCurrentDomainFx::create_sparse_array(const std::string& array_name) {
+void RestCurrentDomainFx::create_sparse_array(
+    const std::string& array_name, bool empty_ndr) {
   uri_ = vfs_test_setup_.array_uri(array_name);
 
   // Create dimensions
@@ -107,9 +109,11 @@ void RestCurrentDomainFx::create_sparse_array(const std::string& array_name) {
   range.min_size = sizeof(uint64_t);
   range.max = &max;
   range.max_size = sizeof(uint64_t);
-  REQUIRE(
-      tiledb_ndrectangle_set_range_for_name(ctx_c_, ndr, "d1", &range) ==
-      TILEDB_OK);
+  if (!empty_ndr) {
+    REQUIRE(
+        tiledb_ndrectangle_set_range_for_name(ctx_c_, ndr, "d1", &range) ==
+        TILEDB_OK);
+  }
   REQUIRE(tiledb_current_domain_set_ndrectangle(crd, ndr) == TILEDB_OK);
   REQUIRE(
       tiledb_array_schema_set_current_domain(ctx_c_, array_schema, crd) ==
@@ -121,7 +125,20 @@ void RestCurrentDomainFx::create_sparse_array(const std::string& array_name) {
 
   // Create array
   rc = tiledb_array_create(ctx_c_, uri_.c_str(), array_schema);
-  CHECK(rc == TILEDB_OK);
+  if (empty_ndr) {
+    CHECK(rc == TILEDB_ERR);
+    tiledb_error_t* err;
+    CHECK(tiledb_ctx_get_last_error(ctx_c_, &err) == TILEDB_OK);
+    const char* errmsg;
+    CHECK(tiledb_error_message(err, &errmsg) == TILEDB_OK);
+    CHECK_THAT(
+        errmsg,
+        Catch::Matchers::Equals("NDRectangle serialization failed. The "
+                                "NDRectangle on the array current "
+                                "domain has no ranges set"));
+  } else {
+    CHECK(rc == TILEDB_OK);
+  }
 
   // Clean up
   REQUIRE(tiledb_ndrectangle_free(&ndr) == TILEDB_OK);
@@ -136,6 +153,10 @@ TEST_CASE_METHOD(
     RestCurrentDomainFx,
     "C API: Current Domain basic behavior",
     "[current_domain][rest]") {
+  // Check that an empty NDRectangle set on a current domain throws on the
+  // client
+  create_sparse_array("currentdomain_array", true);
+
   create_sparse_array("currentdomain_array");
 
   // Open array, read back current domain from schema and check

tiledb/sm/array_schema/ndrectangle.cc

@@ -87,7 +87,7 @@ shared_ptr<NDRectangle> NDRectangle::deserialize(
 
 void NDRectangle::serialize(Serializer& serializer) const {
   for (unsigned d = 0; d < range_data_.size(); ++d) {
-    auto dim{domain_->dimension_ptr(d)};
+    auto dim{domain()->dimension_ptr(d)};
     const auto& r = range_data_[d];
     if (!dim->var_size()) {  // Fixed-sized
       serializer.write(r.data(), r.size());
@@ -109,7 +109,7 @@ void NDRectangle::dump(FILE* out) const {
   std::stringstream ss;
   ss << " - NDRectangle ###" << std::endl;
   for (uint32_t i = 0; i < range_data_.size(); ++i) {
-    auto dtype = domain_->dimension_ptr(i)->type();
+    auto dtype = domain()->dimension_ptr(i)->type();
     ss << "  - " << range_str(range_data_[i], dtype) << std::endl;
   }
 
@@ -125,7 +125,7 @@ void NDRectangle::set_range(const Range& r, uint32_t idx) {
 }
 
 void NDRectangle::set_range_for_name(const Range& r, const std::string& name) {
-  auto idx = domain_->get_dimension_index(name);
+  auto idx = domain()->get_dimension_index(name);
   set_range(r, idx);
 }
 
@@ -138,7 +138,7 @@ const Range& NDRectangle::get_range(uint32_t idx) const {
 }
 
 const Range& NDRectangle::get_range_for_name(const std::string& name) const {
-  auto idx = domain_->get_dimension_index(name);
+  auto idx = domain()->get_dimension_index(name);
   return get_range(idx);
 }
 

tiledb/sm/array_schema/ndrectangle.h

@@ -135,6 +135,12 @@ class NDRectangle {
 
   /** domain accessor */
   shared_ptr<Domain> domain() const {
+    // Guards for a special cased behavior in REST array schema evolution, see
+    // domain_ declaration for a more detailed explanation
+    if (domain_ == nullptr) {
+      throw std::runtime_error(
+          "The Domain instance on this NDRectangle is nullptr");
+    }
     return domain_;
   }
 
@@ -187,7 +193,11 @@ class NDRectangle {
   /** Per dimension ranges of the rectangle */
   NDRange range_data_;
 
-  /** Array Schema domain  */
+  /**
+   * Array Schema domain. This can be nullptr during
+   * array schema evolution on REST when we construct with a nullptr domain_
+   * and set it later during ArraySchema::expand_current_domain to avoid
+   * serializing the domain on the evolution object */
   shared_ptr<Domain> domain_;
 };
 

tiledb/sm/enums/current_domain_type.h

@@ -51,13 +51,13 @@ enum class CurrentDomainType : uint8_t {
 };
 
 /** Returns the string representation of the input current domain type. */
-inline const std::string& current_domain_type_str(
+inline const std::string current_domain_type_str(
     CurrentDomainType current_domain_type) {
   switch (current_domain_type) {
     case CurrentDomainType::NDRECTANGLE:
       return constants::current_domain_ndrectangle_str;
     default:
-      return constants::empty_str;
+      return std::to_string(static_cast<uint8_t>(current_domain_type));
   }
 }
 

tiledb/sm/serialization/array_schema.cc

@@ -1153,11 +1153,13 @@ shared_ptr<ArraySchema> array_schema_from_capnp(
     name = schema_reader.getName().cStr();
   }
 
-  auto crd = make_shared<CurrentDomain>(
-      memory_tracker, constants::current_domain_version);
+  std::shared_ptr<CurrentDomain> crd;
   if (schema_reader.hasCurrentDomain()) {
     crd = current_domain_from_capnp(
         schema_reader.getCurrentDomain(), domain, memory_tracker);
+  } else {
+    crd = make_shared<CurrentDomain>(
+        memory_tracker, constants::current_domain_version);
   }
 
   return make_shared<ArraySchema>(

tiledb/sm/serialization/array_schema_evolution.cc

@@ -155,9 +155,11 @@ Status array_schema_evolution_to_capnp(
   timestamp_builder.set(1, timestamp_range.second);
 
   auto crd = array_schema_evolution->current_domain_to_expand();
-  auto current_domain_builder =
-      array_schema_evolution_builder->initCurrentDomainToExpand();
-  current_domain_to_capnp(crd, &current_domain_builder);
+  if (crd != nullptr) {
+    auto current_domain_builder =
+        array_schema_evolution_builder->initCurrentDomainToExpand();
+    current_domain_to_capnp(crd, &current_domain_builder);
+  }
 
   return Status::Ok();
 }

tiledb/sm/serialization/current_domain.cc

@@ -77,7 +77,12 @@ void ndrectangle_to_capnp(
       // only one range per dimension
       range_buffers_to_capnp({ranges[i]}, range_builder);
     }
+    return;
   }
+
+  throw std::logic_error(
+      "NDRectangle serialization failed. The NDRectangle on the array current "
+      "domain has no ranges set");
 }
 
 shared_ptr<CurrentDomain> current_domain_from_capnp(