finished postgres fetch

backends/postgres/src/postgres_connection.cpp

@@ -1,5 +1,10 @@
 #include "postgres_connection.hpp"
 #include "postgres_error.hpp"
+#include "postgres_result_reader.hpp"
+
+#include "matador/sql/record.hpp"
+
+#include <iostream>
 
 namespace matador::backends::postgres {
 
@@ -41,7 +46,16 @@ std::unique_ptr<sql::query_result_impl> postgres_connection::fetch(const std::st
 
   throw_postgres_error(res, conn_, "postgres", stmt);
 
-  return {};
+  sql::record prototype;
+  auto ncol = PQnfields(res);
+  for (int i = 0; i < ncol; ++i) {
+    const char *col_name = PQfname(res, i);
+    auto type = PQftype(res, i);
+    auto size = PQfmod(res, i);
+    std::cout << "column " << col_name << ", type " << type << " (size: " << size << ")\n";
+    prototype.append({col_name});
+  }
+  return std::move(std::make_unique<sql::query_result_impl>(std::make_unique<postgres_result_reader>(res), std::move(prototype)));
 }
 
 void postgres_connection::prepare(const std::string &stmt)
@@ -55,12 +69,67 @@ size_t postgres_connection::execute(const std::string &stmt)
 
   throw_postgres_error(res, conn_, "postgres", stmt);
 
-  return 0;
+  return sql::to_long_long(PQcmdTuples(res));
+}
+
+sql::data_type_t string2type(const char *type)
+{
+  if (strcmp(type, "int2") == 0) {
+    return sql::data_type_t::type_short;
+  } else if (strcmp(type, "int4") == 0) {
+    return sql::data_type_t::type_int;
+  } else if (strcmp(type, "int8") == 0) {
+    return sql::data_type_t::type_long_long;
+  } else if (strncmp(type, "int8", 6) == 0) {
+    return sql::data_type_t::type_long_long;
+  } else if (strcmp(type, "date") == 0) {
+    return sql::data_type_t::type_date;
+  } else if (strncmp(type, "timestamp", 8) == 0) {
+    return sql::data_type_t::type_time;
+  } else if (strcmp(type, "float4") == 0) {
+    return sql::data_type_t::type_float;
+  } else if (strcmp(type, "float8") == 0) {
+    return sql::data_type_t::type_double;
+  } else if (strncmp(type, "varchar", 7) == 0) {
+    return sql::data_type_t::type_varchar;
+  } else if (strncmp(type, "character varying", 7) == 0) {
+    return sql::data_type_t::type_varchar;
+  } else if (strncmp(type, "text", 0) == 0) {
+    return sql::data_type_t::type_text;
+  } else {
+    return sql::data_type_t::type_unknown;
+  }
 }
 
 sql::record postgres_connection::describe(const std::string &table)
 {
-  return {};
+  std::string stmt(
+    "SELECT ordinal_position, column_name, udt_name, data_type, is_nullable, column_default FROM information_schema.columns WHERE table_schema='public' AND table_name='" + table + "'");
+
+  PGresult *res = PQexec(conn_, stmt.c_str());
+
+  throw_postgres_error(res, conn_, "postgres", stmt);
+
+  postgres_result_reader reader(res);
+  sql::record prototype;
+  while (reader.fetch()) {
+    char *end = nullptr;
+    // Todo: Handle error
+    auto index = strtoul(reader.column(0), &end, 10);
+    std::string name = reader.column(1);
+
+    // Todo: extract size
+    auto type = (string2type(reader.column(2)));
+    end = nullptr;
+    utils::constraints options{};
+    if (strtoul(reader.column(4), &end, 10) == 0) {
+      options = utils::constraints::NOT_NULL;
+    }
+    // f.default_value(res->column(4));
+    prototype.append({name, type, {options}});
+  }
+
+  return std::move(prototype);
 }
 
 bool postgres_connection::exists(const std::string &table_name)