query/procedure: Expose vertex ID through C API

Reviewers: mferencevic, ipaljak

Reviewed By: ipaljak

Subscribers: pullbot

Differential Revision: https://phabricator.memgraph.io/D2568

include/mg_procedure.h

@@ -450,6 +450,16 @@ struct mgp_edges_iterator;
 /// Free the memory used by a mgp_edges_iterator.
 void mgp_edges_iterator_destroy(struct mgp_edges_iterator *it);
 
+/// ID of a vertex; valid during a single query execution.
+struct mgp_vertex_id {
+  int64_t as_int;
+};
+
+/// Get the ID of given vertex.
+/// The ID is only valid for a single query execution, you should never store it
+/// globally in a query module.
+struct mgp_vertex_id mgp_vertex_get_id(const struct mgp_vertex *v);
+
 /// Copy a mgp_vertex.
 /// Returned pointer must be freed with mgp_vertex_destroy.
 /// NULL is returned if unable to allocate a mgp_vertex.
@@ -552,6 +562,13 @@ struct mgp_properties_iterator *mgp_edge_iter_properties(
 /// State of the graph database.
 struct mgp_graph;
 
+/// Return the vertex corresponding to given ID.
+/// The returned vertex must be freed using mgp_vertex_destroy.
+/// NULL is returned if unable to allocate the vertex or if ID is not valid.
+struct mgp_vertex *mgp_graph_get_vertex_by_id(const struct mgp_graph *g,
+                                              struct mgp_vertex_id id,
+                                              struct mgp_memory *memory);
+
 /// Iterator over vertices.
 struct mgp_vertices_iterator;
 

src/query/db_accessor.hpp

@@ -528,6 +528,13 @@ class DbAccessor final {
   explicit DbAccessor(storage::Storage::Accessor *accessor)
       : accessor_(accessor) {}
 
+  std::optional<VertexAccessor> FindVertex(storage::Gid gid,
+                                           storage::View view) {
+    auto maybe_vertex = accessor_->FindVertex(gid, view);
+    if (maybe_vertex) return VertexAccessor(*maybe_vertex);
+    return std::nullopt;
+  }
+
   VerticesIterable Vertices(storage::View view) {
     return VerticesIterable(accessor_->Vertices(view));
   }
@@ -730,6 +737,14 @@ class DbAccessor final {
     }
   }
 
+  std::optional<VertexAccessor> FindVertex(storage::Gid gid,
+                                           storage::View view) {
+    auto maybe_vertex =
+        dba_->FindVertexOptional(gid, view == storage::View::NEW);
+    if (maybe_vertex) return VertexAccessor(*maybe_vertex);
+    return std::nullopt;
+  }
+
   auto Vertices(storage::View view) {
     auto vertices = dba_->Vertices(view == storage::View::NEW);
     return VerticesIterable<decltype(vertices)>(std::move(vertices));

src/query/procedure/mg_procedure_impl.cpp

@@ -858,6 +858,10 @@ const mgp_property *mgp_properties_iterator_next(mgp_properties_iterator *it) {
   }
 }
 
+mgp_vertex_id mgp_vertex_get_id(const mgp_vertex *v) {
+  return mgp_vertex_id{.as_int = v->impl.Gid().AsInt()};
+}
+
 mgp_vertex *mgp_vertex_copy(const mgp_vertex *v, mgp_memory *memory) {
   return new_mgp_object<mgp_vertex>(memory, *v);
 }
@@ -1184,6 +1188,15 @@ mgp_properties_iterator *mgp_edge_iter_properties(const mgp_edge *e,
   }
 }
 
+mgp_vertex *mgp_graph_get_vertex_by_id(const mgp_graph *graph, mgp_vertex_id id,
+                                       mgp_memory *memory) {
+  auto maybe_vertex =
+      graph->impl->FindVertex(storage::Gid::FromInt(id.as_int), graph->view);
+  if (maybe_vertex)
+    return new_mgp_object<mgp_vertex>(memory, *maybe_vertex, graph);
+  return nullptr;
+}
+
 void mgp_vertices_iterator_destroy(mgp_vertices_iterator *it) {
   delete_mgp_object(it);
 }