public void AddVertices_adds_vertices()
{
var model = new Model();
var entityTypeA = model.AddEntityType(typeof(A));
var entityTypeB = model.AddEntityType(typeof(B));
var graph = new BidirectionalAdjacencyListGraph <EntityType>();
graph.AddVertices(new[] { entityTypeA, entityTypeB });
Assert.Equal(new[] { entityTypeA, entityTypeB }, graph.Vertices);
}
// To avoid violating store constraints the modification commands must be sorted
// according to these rules:
//
// 1. Commands adding rows or modifying the candidate key values (when supported) must precede
// commands modifying or adding rows that will be referencing the former
// 2. Commands deleting rows or modifying the foreign key values must precede
// commands deleting rows or modifying the candidate key values (when supported) of rows
// that are currently being referenced by the former
protected virtual IEnumerable <List <ModificationCommand> > TopologicalSort([NotNull] IEnumerable <ModificationCommand> commands)
{
Check.NotNull(commands, "commands");
var modificationCommandGraph = new BidirectionalAdjacencyListGraph <ModificationCommand>();
modificationCommandGraph.AddVertices(commands);
// The predecessors map allows to populate the graph in linear time
var predecessorsMap = CreateKeyValuePredecessorMap(modificationCommandGraph);
AddForeignKeyEdges(modificationCommandGraph, predecessorsMap);
return(modificationCommandGraph.TopologicalSort());
}
public void AddEdge_adds_edge()
{
var model = new Model();
var entityTypeA = model.AddEntityType(typeof(A));
var entityTypeB = model.AddEntityType(typeof(B));
var entityTypeC = model.AddEntityType(typeof(C));
var graph = new BidirectionalAdjacencyListGraph <EntityType>();
graph.AddVertex(entityTypeA);
graph.AddVertex(entityTypeB);
graph.AddVertex(entityTypeC);
graph.AddEdge(entityTypeA, entityTypeB);
graph.AddEdge(entityTypeA, entityTypeC);
graph.AddEdge(entityTypeB, entityTypeC);
Assert.Equal(new[] { entityTypeB, entityTypeC }, graph.GetOutgoingNeighbours(entityTypeA));
Assert.Equal(new[] { entityTypeA, entityTypeB }, graph.GetIncomingNeighbours(entityTypeC));
}
private void AddForeignKeyEdges(
BidirectionalAdjacencyListGraph <ModificationCommand> commandGraph,
Dictionary <KeyValue, List <ModificationCommand> > predecessorsMap)
{
foreach (var command in commandGraph.Vertices)
{
if (command.EntityState == EntityState.Modified ||
command.EntityState == EntityState.Added)
{
foreach (var stateEntry in command.StateEntries)
{
foreach (var foreignKey in stateEntry.EntityType.ForeignKeys)
{
var dependentKeyValue = CreateDependentKeyValue(stateEntry, foreignKey, ValueType.Current);
if (dependentKeyValue.Key != EntityKey.NullEntityKey)
{
List <ModificationCommand> predecessorCommands;
if (predecessorsMap.TryGetValue(dependentKeyValue, out predecessorCommands))
{
foreach (var predecessor in predecessorCommands)
{
if (predecessor != command)
{
commandGraph.AddEdge(predecessor, command);
}
}
}
}
}
}
}
// TODO: also examine modified entities here when principal key modification is supported
if (command.EntityState == EntityState.Deleted)
{
foreach (var stateEntry in command.StateEntries)
{
foreach (var foreignKey in stateEntry.EntityType.GetReferencingForeignKeys())
{
var principalKeyValue = CreatePrincipalKeyValue(stateEntry.OriginalValues, foreignKey, ValueType.Original);
if (principalKeyValue.Key != EntityKey.NullEntityKey)
{
List <ModificationCommand> predecessorCommands;
if (predecessorsMap.TryGetValue(principalKeyValue, out predecessorCommands))
{
foreach (var predecessor in predecessorCommands)
{
if (predecessor != command)
{
commandGraph.AddEdge(predecessor, command);
}
}
}
}
}
}
}
}
}
