Apply patch before to validate "if"

src/json-validator.cpp

@@ -498,6 +498,37 @@ bool logical_combination<oneOf>::is_validate_complete(const json &instance, cons
 	return count > 1;
 }
 
+json apply_patch_from(const json &instance, const json_patch &patch, const json::json_pointer &ptr)
+{
+	if (patch.operator json().empty()) {
+		return instance;
+	}
+
+	json patched_instance = json::parse(instance.dump());
+
+	json array = patch.operator json();
+	std::string ptr_string = ptr.to_string();
+	size_t ptr_string_length = ptr_string.length();
+	for (auto item = array.begin(); item != array.end(); ++item) {
+		std::string path = item->at("path");
+		if (path.find(ptr_string) != 0)
+			continue;
+		try {
+			json single_patch = {
+			    {
+			        {"path", path.substr(ptr_string_length)}, //
+			        {"op", item->at("op")},                   //
+			        {"value", item->at("value")}              //
+			    }                                             //
+			};
+			patched_instance = patched_instance.patch(single_patch);
+		} catch (...) {
+		}
+	}
+
+	return patched_instance;
+}
+
 class type_schema : public schema
 {
 	std::vector<std::shared_ptr<schema>> type_;
@@ -543,14 +574,14 @@ class type_schema : public schema
 
 		if (if_) {
 			first_error_handler err;
-
-			if_->validate(ptr, instance, patch, err);
+			json patched_instance = apply_patch_from(instance, patch, ptr);
+			if_->validate(ptr, patched_instance, patch, err);
 			if (!err) {
 				if (then_)
-					then_->validate(ptr, instance, patch, e);
+					then_->validate(ptr, patched_instance, patch, e);
 			} else {
 				if (else_)
-					else_->validate(ptr, instance, patch, e);
+					else_->validate(ptr, patched_instance, patch, e);
 			}
 		}
 	}

test/CMakeLists.txt

@@ -73,3 +73,7 @@ add_test(NAME issue-149-entry-selection COMMAND issue-149-entry-selection)
 add_executable(issue-189-default-values issue-189-default-values.cpp)
 target_link_libraries(issue-189-default-values nlohmann_json_schema_validator)
 add_test(NAME issue-189-default-values COMMAND issue-189-default-values)
+
+add_executable(issue-228-if-default-values issue-228-if-default-values.cpp)
+target_link_libraries(issue-228-if-default-values nlohmann_json_schema_validator)
+add_test(NAME issue-228-if-default-values COMMAND issue-228-if-default-values)

test/issue-228-if-default-values.cpp

@@ -0,0 +1,53 @@
+#include <iostream>
+#include <nlohmann/json-schema.hpp>
+
+using nlohmann::json;
+using nlohmann::json_uri;
+using nlohmann::json_schema::json_validator;
+
+static const json default_schema = R"(
+{
+    "$schema": "http://json-schema.org/draft-07/schema#",
+    "type": "object",
+    "properties": {
+        "condition": {
+            "type": "boolean",
+            "default": false
+        },
+        "data": {
+            "type": "string",
+            "default": "default"
+        }
+    },
+    "if": {
+        "properties": { "condition": { "const": true } }
+    },
+    "then": {
+        "required": ["data"]
+    }
+})"_json;
+
+static void loader(const json_uri &uri, json &schema)
+{
+	schema = default_schema;
+}
+
+int main(void)
+{
+	json_validator validator(loader);
+
+	validator.set_root_schema(default_schema);
+
+	json empty_object = json::object();
+	validator.validate(empty_object);
+
+	json enable_condition = R"({"condition": true})"_json;
+	auto patch = validator.validate(enable_condition);
+	enable_condition.patch_inplace(patch);
+	if (enable_condition.at("data") != "default") {
+		std::cerr << "Unexpected data: " << enable_condition.at("data") << " instead of 'default'" << std::endl;
+		return 1;
+	}
+
+	return 0;
+}