Add cypherl output format (#54)

README.md

@@ -123,6 +123,19 @@ memgraph> :quit
 Bye
 ```
 
+## Export & import into Memgraph
+
+An interesting use-case for `mgconsole` is exporting and importing data.
+You can close the loop by running the following example queries:
+
+```
+# Export to cypherl formatted data file
+echo "DUMP DATABASE;" | mgconsole --output-format=cypherl > data.cypherl
+
+# Import from cypherl file
+cat data.cypherl | mgconsole
+```
+
 ## Batched and parallelized import (EXPERIMENTAL)
 
 Since Memgraph v2 expects vertices to come first (vertices has to exist to
@@ -137,7 +150,7 @@ leverage parallelism in the best possible way.
 
 ```
 cat data.cypherl | mgconsole --import-mode=batched-parallel
-// STORAGE MODE IN_MEMORY_ANALYTICAL; is optional
+# STORAGE MODE IN_MEMORY_ANALYTICAL; is optional
 ```
 
 IMPORTANT NOTE: Inside the import file, vertices always have to come first

src/main.cpp

@@ -64,12 +64,12 @@ DEFINE_bool(use_ssl, false, "Use SSL when connecting to the server.");
 DEFINE_bool(fit_to_screen, false, "Fit output width to screen width.");
 DEFINE_bool(term_colors, false, "Use terminal colors syntax highlighting.");
 DEFINE_string(output_format, "tabular",
-              "Query output format can be csv or tabular. If output format is "
+              "Query output format can be csv, tabular or cypherl. If output format is "
               "not tabular `fit-to-screen` flag is ignored.");
 DEFINE_bool(verbose_execution_info, false,
             "Output the additional information about query such as query cost, parsing, planning and execution times.");
 DEFINE_validator(output_format, [](const char *, const std::string &value) {
-  if (value == constants::kCsvFormat || value == constants::kTabularFormat) {
+  if (value == constants::kCsvFormat || value == constants::kTabularFormat || value == constants::kCypherlFormat) {
     return true;
   }
   return false;

src/utils/constants.hpp

@@ -37,6 +37,7 @@ constexpr const std::string_view kCommandDocs = ":docs";
 // Supported formats.
 constexpr const std::string_view kCsvFormat = "csv";
 constexpr const std::string_view kTabularFormat = "tabular";
+constexpr const std::string_view kCypherlFormat = "cypherl";
 
 // Supported modes.
 constexpr const std::string_view kSerialMode = "serial";

src/utils/utils.cpp

@@ -1186,12 +1186,28 @@ void PrintCsv(const std::vector<std::string> &header, const std::vector<mg_memor
   }
 }
 
+void PrintCypherl(const std::vector<std::string> &header, const std::vector<mg_memory::MgListPtr> &records) {
+  if (header.size() != 1) {
+    std::cerr << "ERROR: cypherl output format requires exactly 1 output column" << std::endl;
+    std::exit(1);
+  }
+  for (size_t record_i = 0; record_i < records.size(); ++record_i) {
+    const auto &fields = records[record_i];
+    for (uint32_t field_i = 0; field_i < mg_list_size(fields.get()); ++field_i) {
+      const auto *query_ptr = mg_value_string(mg_list_at(fields.get(), field_i));
+      std::cout << std::string(mg_string_data(query_ptr), mg_string_size(query_ptr)) << std::endl;
+    }
+  }
+}
+
 void Output(const std::vector<std::string> &header, const std::vector<mg_memory::MgListPtr> &records,
             const OutputOptions &out_opts, const CsvOptions &csv_opts) {
   if (out_opts.output_format == constants::kTabularFormat) {
     PrintTabular(header, records, out_opts.fit_to_screen);
   } else if (out_opts.output_format == constants::kCsvFormat) {
     PrintCsv(header, records, csv_opts);
+  } else if (out_opts.output_format == constants::kCypherlFormat) {
+    PrintCypherl(header, records);
   }
 }