refactor: make PartitionSpec ctor private and add factory methods with validation

src/iceberg/json_internal.cc

@@ -533,7 +533,8 @@ Result<std::unique_ptr<PartitionField>> PartitionFieldFromJson(
 }
 
 Result<std::unique_ptr<PartitionSpec>> PartitionSpecFromJson(
-    const std::shared_ptr<Schema>& schema, const nlohmann::json& json) {
+    const std::shared_ptr<Schema>& schema, const nlohmann::json& json,
+    int32_t default_spec_id) {
   ICEBERG_ASSIGN_OR_RAISE(auto spec_id, GetJsonValue<int32_t>(json, kSpecId));
   ICEBERG_ASSIGN_OR_RAISE(auto fields, GetJsonValue<nlohmann::json>(json, kFields));
 
@@ -542,9 +543,18 @@ Result<std::unique_ptr<PartitionSpec>> PartitionSpecFromJson(
     ICEBERG_ASSIGN_OR_RAISE(auto partition_field, PartitionFieldFromJson(field_json));
     partition_fields.push_back(std::move(*partition_field));
   }
-  // TODO(Li Feiyang):use a new PartitionSpec::Make to find the source field of each
-  // partition field from schema and then verify it
-  return std::make_unique<PartitionSpec>(spec_id, std::move(partition_fields));
+
+  std::unique_ptr<PartitionSpec> spec;
+  if (default_spec_id == spec_id) {
+    ICEBERG_ASSIGN_OR_RAISE(
+        spec, PartitionSpec::Make(*schema, spec_id, std::move(partition_fields),
+                                  /*allow_missing_fields=*/false));
+  } else {
+    ICEBERG_ASSIGN_OR_RAISE(
+        spec, PartitionSpec::Make(*schema, spec_id, std::move(partition_fields),
+                                  /*allow_missing_fields=*/true));
+  }
+  return spec;
 }
 
 Result<std::unique_ptr<SnapshotRef>> SnapshotRefFromJson(const nlohmann::json& json) {
@@ -885,8 +895,8 @@ Status ParsePartitionSpecs(const nlohmann::json& json, int8_t format_version,
     ICEBERG_ASSIGN_OR_RAISE(default_spec_id, GetJsonValue<int32_t>(json, kDefaultSpecId));
 
     for (const auto& spec_json : spec_array) {
-      ICEBERG_ASSIGN_OR_RAISE(auto spec,
-                              PartitionSpecFromJson(current_schema, spec_json));
+      ICEBERG_ASSIGN_OR_RAISE(
+          auto spec, PartitionSpecFromJson(current_schema, spec_json, default_spec_id));
       partition_specs.push_back(std::move(spec));
     }
   } else {
@@ -917,10 +927,11 @@ Status ParsePartitionSpecs(const nlohmann::json& json, int8_t format_version,
                           std::move(field->transform()));
     }
 
-    // TODO(Li Feiyang):use a new PartitionSpec::Make to find the source field of each
-    // partition field from schema and then verify it
-    auto spec =
-        std::make_unique<PartitionSpec>(PartitionSpec::kInitialSpecId, std::move(fields));
+    // Create partition spec with schema validation
+    ICEBERG_ASSIGN_OR_RAISE(
+        auto spec,
+        PartitionSpec::Make(*current_schema, PartitionSpec::kInitialSpecId,
+                            std::move(fields), /*allow_missing_fields=*/false));
     default_spec_id = spec->spec_id();
     partition_specs.push_back(std::move(spec));
   }

src/iceberg/json_internal.h

@@ -176,10 +176,12 @@ ICEBERG_EXPORT Result<std::string> ToJsonString(const PartitionSpec& partition_s
 ///
 /// \param schema The current schema.
 /// \param json The JSON object representing a `PartitionSpec`.
+/// \param default_spec_id The default spec ID from the table metadata.
 /// \return An `expected` value containing either a `PartitionSpec` object or an error. If
 /// the JSON is malformed or missing expected fields, an error will be returned.
 ICEBERG_EXPORT Result<std::unique_ptr<PartitionSpec>> PartitionSpecFromJson(
-    const std::shared_ptr<Schema>& schema, const nlohmann::json& json);
+    const std::shared_ptr<Schema>& schema, const nlohmann::json& json,
+    int32_t default_spec_id);
 
 /// \brief Serializes a `SnapshotRef` object to JSON.
 ///

src/iceberg/partition_field.cc

@@ -22,7 +22,6 @@
 #include <format>
 
 #include "iceberg/transform.h"
-#include "iceberg/type.h"
 #include "iceberg/util/formatter.h"  // IWYU pragma: keep
 
 namespace iceberg {

src/iceberg/partition_spec.cc

@@ -20,15 +20,19 @@
 #include "iceberg/partition_spec.h"
 
 #include <algorithm>
+#include <cstdint>
 #include <format>
 #include <memory>
 #include <ranges>
+#include <unordered_map>
 
+#include "iceberg/result.h"
 #include "iceberg/schema.h"
 #include "iceberg/schema_field.h"
 #include "iceberg/transform.h"
 #include "iceberg/util/formatter.h"  // IWYU pragma: keep
 #include "iceberg/util/macros.h"
+#include "iceberg/util/type_util.h"
 
 namespace iceberg {
 
@@ -47,9 +51,8 @@ PartitionSpec::PartitionSpec(int32_t spec_id, std::vector<PartitionField> fields
 }
 
 const std::shared_ptr<PartitionSpec>& PartitionSpec::Unpartitioned() {
-  static const std::shared_ptr<PartitionSpec> unpartitioned =
-      std::make_shared<PartitionSpec>(kInitialSpecId, std::vector<PartitionField>{},
-                                      kLegacyPartitionDataIdStart - 1);
+  static const std::shared_ptr<PartitionSpec> unpartitioned(new PartitionSpec(
+      kInitialSpecId, std::vector<PartitionField>{}, kLegacyPartitionDataIdStart - 1));
   return unpartitioned;
 }
 
@@ -104,4 +107,67 @@ bool PartitionSpec::Equals(const PartitionSpec& other) const {
   return spec_id_ == other.spec_id_ && fields_ == other.fields_;
 }
 
+Status PartitionSpec::Validate(const Schema& schema, bool allow_missing_fields) const {
+  std::unordered_map<int32_t, int32_t> parents = indexParents(schema);
+  for (const auto& partition_field : fields_) {
+    ICEBERG_ASSIGN_OR_RAISE(auto source_field,
+                            schema.FindFieldById(partition_field.source_id()));
+    // In the case the underlying field is dropped, we cannot check if they are compatible
+    if (allow_missing_fields && !source_field.has_value()) {
+      continue;
+    }
+    const auto& field_transform = partition_field.transform();
+
+    // In the case of a Version 1 partition-spec field gets deleted, it is replaced with a
+    // void transform, see: https://iceberg.apache.org/spec/#partition-transforms. We
+    // don't care about the source type since a VoidTransform is always compatible and
+    // skip the checks
+    if (field_transform->transform_type() != TransformType::kVoid) {
+      if (!source_field.has_value()) {
+        return InvalidArgument("Cannot find source column for partition field: {}",
+                               partition_field);
+      }
+      const auto& source_type = source_field.value().get().type();
+      if (!field_transform->CanTransform(*source_type)) {
+        return InvalidArgument("Invalid source type {} for transform {}",
+                               source_type->ToString(), field_transform->ToString());
+      }
+
+      // The only valid parent types for a PartitionField are StructTypes. This must be
+      // checked recursively.
+      auto parent_id_iter = parents.find(partition_field.source_id());
+      while (parent_id_iter != parents.end()) {
+        int32_t parent_id = parent_id_iter->second;
+        ICEBERG_ASSIGN_OR_RAISE(auto parent_field, schema.FindFieldById(parent_id));
+        if (!parent_field.has_value()) {
+          return InvalidArgument("Cannot find parent field with ID: {}", parent_id);
+        }
+        const auto& parent_type = parent_field.value().get().type();
+        if (parent_type->type_id() != TypeId::kStruct) {
+          return InvalidArgument("Invalid partition field parent type: {}",
+                                 parent_type->ToString());
+        }
+        parent_id_iter = parents.find(parent_id);
+      }
+    }
+  }
+  return {};
+}
+
+Result<std::unique_ptr<PartitionSpec>> PartitionSpec::Make(
+    const Schema& schema, int32_t spec_id, std::vector<PartitionField> fields,
+    bool allow_missing_fields, std::optional<int32_t> last_assigned_field_id) {
+  auto partition_spec = std::unique_ptr<PartitionSpec>(
+      new PartitionSpec(spec_id, std::move(fields), last_assigned_field_id));
+  ICEBERG_RETURN_UNEXPECTED(partition_spec->Validate(schema, allow_missing_fields));
+  return partition_spec;
+}
+
+Result<std::unique_ptr<PartitionSpec>> PartitionSpec::Make(
+    int32_t spec_id, std::vector<PartitionField> fields,
+    std::optional<int32_t> last_assigned_field_id) {
+  return std::unique_ptr<PartitionSpec>(
+      new PartitionSpec(spec_id, std::move(fields), last_assigned_field_id));
+}
+
 }  // namespace iceberg

src/iceberg/partition_spec.h

@@ -50,16 +50,6 @@ class ICEBERG_EXPORT PartitionSpec : public util::Formattable {
   static constexpr int32_t kLegacyPartitionDataIdStart = 1000;
   static constexpr int32_t kInvalidPartitionFieldId = -1;
 
-  /// \brief Create a new partition spec.
-  ///
-  /// \param schema The table schema.
-  /// \param spec_id The spec ID.
-  /// \param fields The partition fields.
-  /// \param last_assigned_field_id The last assigned field ID. If not provided, it will
-  /// be calculated from the fields.
-  PartitionSpec(int32_t spec_id, std::vector<PartitionField> fields,
-                std::optional<int32_t> last_assigned_field_id = std::nullopt);
-
   /// \brief Get an unsorted partition spec singleton.
   static const std::shared_ptr<PartitionSpec>& Unpartitioned();
 
@@ -80,7 +70,49 @@ class ICEBERG_EXPORT PartitionSpec : public util::Formattable {
     return lhs.Equals(rhs);
   }
 
+  /// \brief Validates the partition spec against a schema.
+  /// \param schema The schema to validate against.
+  /// \param allowMissingFields Whether to skip validation for partition fields whose
+  /// source columns have been dropped from the schema.
+  /// \return Error status if the partition spec is invalid.
+  Status Validate(const Schema& schema, bool allow_missing_fields) const;
+
+  /// \brief Create a PartitionSpec binding to a schema.
+  /// \param schema The schema to bind the partition spec to.
+  /// \param spec_id The spec ID.
+  /// \param fields The partition fields.
+  /// \param allowMissingFields Whether to skip validation for partition fields whose
+  /// source columns have been dropped from the schema.
+  /// \param last_assigned_field_id The last assigned field ID assigned to ensure new
+  /// fields get unique IDs.
+  /// \return A Result containing the partition spec or an error.
+  static Result<std::unique_ptr<PartitionSpec>> Make(
+      const Schema& schema, int32_t spec_id, std::vector<PartitionField> fields,
+      bool allow_missing_fields,
+      std::optional<int32_t> last_assigned_field_id = std::nullopt);
+
+  /// \brief Create a PartitionSpec without binding to a schema.
+  /// \param spec_id The spec ID.
+  /// \param fields The partition fields.
+  /// \param last_assigned_field_id The last assigned field ID assigned to ensure new
+  /// fields get unique IDs.
+  /// \return A Result containing the partition spec or an error.
+  /// \note This method does not check whether the sort fields are valid for any schema.
+  static Result<std::unique_ptr<PartitionSpec>> Make(
+      int32_t spec_id, std::vector<PartitionField> fields,
+      std::optional<int32_t> last_assigned_field_id = std::nullopt);
+
  private:
+  /// \brief Create a new partition spec.
+  ///
+  /// \param schema The table schema.
+  /// \param spec_id The spec ID.
+  /// \param fields The partition fields.
+  /// \param last_assigned_field_id The last assigned field ID. If not provided, it will
+  /// be calculated from the fields.
+  PartitionSpec(int32_t spec_id, std::vector<PartitionField> fields,
+                std::optional<int32_t> last_assigned_field_id = std::nullopt);
+
   /// \brief Compare two partition specs for equality.
   bool Equals(const PartitionSpec& other) const;
 

src/iceberg/sort_order.cc

@@ -90,7 +90,7 @@ bool SortOrder::Equals(const SortOrder& other) const {
 Status SortOrder::Validate(const Schema& schema) const {
   for (const auto& field : fields_) {
     ICEBERG_ASSIGN_OR_RAISE(auto schema_field, schema.FindFieldById(field.source_id()));
-    if (!schema_field.has_value() || schema_field == std::nullopt) {
+    if (!schema_field.has_value()) {
       return InvalidArgument("Cannot find source column for sort field: {}", field);
     }
 

src/iceberg/sort_order.h

@@ -88,7 +88,6 @@ class ICEBERG_EXPORT SortOrder : public util::Formattable {
   /// \param fields The sort fields.
   /// \return A Result containing the SortOrder or an error.
   /// \note This method does not check whether the sort fields are valid for any schema.
-  /// Use IsBoundToSchema to check if the sort order is valid for a given schema.
   static Result<std::unique_ptr<SortOrder>> Make(int32_t sort_id,
                                                  std::vector<SortField> fields);
 

src/iceberg/test/json_internal_test.cc

@@ -103,14 +103,13 @@ TEST(JsonInternalTest, SortField) {
 
 TEST(JsonInternalTest, SortOrder) {
   auto schema = std::make_shared<Schema>(
-      std::vector<SchemaField>{SchemaField(5, "region", iceberg::string(), false),
-                               SchemaField(7, "ts", iceberg::int64(), false)},
+      std::vector<SchemaField>{SchemaField(5, "region", string(), false),
+                               SchemaField(7, "ts", int64(), false)},
       /*schema_id=*/100);
   auto identity_transform = Transform::Identity();
   SortField st_ts(5, identity_transform, SortDirection::kAscending, NullOrder::kFirst);
   SortField st_bar(7, identity_transform, SortDirection::kDescending, NullOrder::kLast);
-  ICEBERG_UNWRAP_OR_FAIL(auto sort_order, SortOrder::Make(100, {st_ts, st_bar}));
-  EXPECT_TRUE(sort_order->Validate(*schema));
+  ICEBERG_UNWRAP_OR_FAIL(auto sort_order, SortOrder::Make(*schema, 100, {st_ts, st_bar}));
   nlohmann::json expected_sort_order =
       R"({"order-id":100,"fields":[
           {"transform":"identity","source-id":5,"direction":"asc","null-order":"nulls-first"},
@@ -132,7 +131,7 @@ TEST(JsonInternalTest, PartitionField) {
   TestJsonConversion(field, expected_json);
 }
 
-TEST(JsonPartitionTest, PartitionFieldFromJsonMissingField) {
+TEST(JsonInternalTest, PartitionFieldFromJsonMissingField) {
   nlohmann::json invalid_json =
       R"({"field-id":101,"transform":"identity","name":"region"})"_json;
   // missing source-id
@@ -143,15 +142,19 @@ TEST(JsonPartitionTest, PartitionFieldFromJsonMissingField) {
   EXPECT_THAT(result, HasErrorMessage("Missing 'source-id'"));
 }
 
-TEST(JsonPartitionTest, PartitionSpec) {
+TEST(JsonInternalTest, PartitionSpec) {
   auto schema = std::make_shared<Schema>(
       std::vector<SchemaField>{SchemaField(3, "region", string(), false),
                                SchemaField(5, "ts", int64(), false)},
       /*schema_id=*/100);
   auto identity_transform = Transform::Identity();
-  PartitionSpec spec(1, {PartitionField(3, 101, "region", identity_transform),
-                         PartitionField(5, 102, "ts", identity_transform)});
-  auto json = ToJson(spec);
+  ICEBERG_UNWRAP_OR_FAIL(
+      auto spec,
+      PartitionSpec::Make(*schema, 1,
+                          {PartitionField(3, 101, "region", identity_transform),
+                           PartitionField(5, 102, "ts", identity_transform)},
+                          false));
+  auto json = ToJson(*spec);
   nlohmann::json expected_json = R"({"spec-id": 1,
                                      "fields": [
                                        {"source-id": 3,
@@ -165,9 +168,9 @@ TEST(JsonPartitionTest, PartitionSpec) {
 
   EXPECT_EQ(json, expected_json);
 
-  auto parsed_spec_result = PartitionSpecFromJson(schema, json);
+  auto parsed_spec_result = PartitionSpecFromJson(schema, json, 1);
   ASSERT_TRUE(parsed_spec_result.has_value()) << parsed_spec_result.error().message;
-  EXPECT_EQ(spec, *parsed_spec_result.value());
+  EXPECT_EQ(*spec, *parsed_spec_result.value());
 }
 
 TEST(JsonInternalTest, SnapshotRefBranch) {

src/iceberg/test/manifest_reader_writer_test.cc

@@ -34,6 +34,7 @@
 #include "iceberg/test/temp_file_test_base.h"
 #include "iceberg/test/test_common.h"
 #include "iceberg/transform.h"
+#include "iceberg/type.h"
 
 namespace iceberg {
 
@@ -186,7 +187,8 @@ TEST_F(ManifestV1Test, WritePartitionedTest) {
   auto identity_transform = Transform::Identity();
   std::vector<PartitionField> fields{
       PartitionField(1, 1000, "order_ts_hour", identity_transform)};
-  auto partition_spec = std::make_shared<PartitionSpec>(1, fields);
+  ICEBERG_UNWRAP_OR_FAIL(std::shared_ptr<PartitionSpec> partition_spec,
+                         PartitionSpec::Make(*table_schema, 1, fields, false));
 
   auto expected_entries = PreparePartitionedTestData();
   auto write_manifest_path = CreateNewTempFilePath();