fixed backend tests (progress)

backends/postgres/src/postgres_connection.cpp

@@ -10,6 +10,7 @@
 
 #include "matador/sql/internal/query_result_impl.hpp"
 
+#include <algorithm>
 #include <sstream>
 
 namespace matador::backends::postgres {
@@ -79,6 +80,8 @@ utils::result<utils::version, utils::error> postgres_connection::server_version(
   });
 }
 
+utils::basic_type oid2type(Oid oid);
+
 utils::result<std::unique_ptr<sql::query_result_impl>, utils::error> postgres_connection::fetch(const sql::query_context &context) {
   PGresult *res = PQexec(conn_, context.sql.c_str());
 
@@ -86,16 +89,28 @@ utils::result<std::unique_ptr<sql::query_result_impl>, utils::error> postgres_co
     return utils::failure(make_error(sql::error_code::FETCH_FAILED, res, conn_, "Failed to fetch", context.sql));
   }
 
-//  std::vector<object::column_definition> prototype;
-//  const auto num_col = PQnfields(res);
-//  for (int i = 0; i < num_col; ++i) {
-//    const char *col_name = PQfname(res, i);
-//    auto type = PQftype(res, i);
-//    auto size = PQfmod(res, i);
-//    prototype.emplace_back(col_name);
-//  }
+  // const auto is_unknown = std::all_of( context.prototype.begin(), context.prototype.end(), [](const object::attribute_definition &a) {return a.is_null();} );
+  // if (!is_unknown) {
+    // return utils::ok(std::make_unique<sql::query_result_impl>(std::make_unique<postgres_result_reader>(res), context.prototype));
+  // }
 
-  return utils::ok(std::make_unique<sql::query_result_impl>(std::make_unique<postgres_result_reader>(res), context.prototype));
+  std::vector<object::attribute_definition> prototype = context.prototype;
+
+  const auto num_col = PQnfields(res);
+  if (prototype.size() != num_col) {
+    return utils::failure(make_error(sql::error_code::FETCH_FAILED, res, conn_, "Number of received columns doesn't match expected columns.", context.sql));
+  }
+  for (int i = 0; i < num_col; ++i) {
+      if (!prototype.at(i).is_null()) {
+          continue;
+      }
+      const auto type = oid2type(PQftype(res, i));
+      // const char *col_name = PQfname(res, i);
+      // const auto size = PQfmod(res, i);
+      prototype.at(i).type(type);
+  }
+
+  return utils::ok(std::make_unique<sql::query_result_impl>(std::make_unique<postgres_result_reader>(res), prototype));
 }
 
 std::string postgres_connection::generate_statement_name(const sql::query_context &query) {
@@ -141,6 +156,37 @@ utils::result<size_t, utils::error> postgres_connection::execute(const std::stri
   return utils::ok(static_cast<size_t>(affected_rows));
 }
 
+utils::basic_type oid2type(const Oid oid) {
+    switch (oid) {
+        case 16:
+            return utils::basic_type::type_bool;
+        case 17:
+            return utils::basic_type::type_blob;
+        case 18:
+            return utils::basic_type::type_int8;
+        case 21:
+            return utils::basic_type::type_int16;
+        case 23:
+            return utils::basic_type::type_int32;
+        case 20:
+            return utils::basic_type::type_int64;
+        case 24:
+            return utils::basic_type::type_text;
+        case 1043:
+            return utils::basic_type::type_varchar;
+        case 700:
+            return utils::basic_type::type_float;
+        case 701:
+            return utils::basic_type::type_double;
+        case 1082:
+            return utils::basic_type::type_date;
+        case 1114:
+            return utils::basic_type::type_time;
+        default:
+            return utils::basic_type::type_null;
+    }
+}
+
 utils::basic_type string2type(const char *type) {
   if (strcmp(type, "int2") == 0) {
     return utils::basic_type::type_int16;