/// <summary>
/// Generates code (AST) for single association in both directions using properties and/or extension methods.
/// </summary>
/// <param name="association">Association model.</param>
/// <param name="extensionAssociations">Association extensions region provider.</param>
/// <param name="entityAssociations">Assocation property groups for each entity.</param>
/// <param name="extensionEntityAssociations">Association methods groupsfor each entity.</param>
private void BuildAssociation(
AssociationModel association,
Func <RegionGroup> extensionAssociations,
Dictionary <EntityModel, PropertyGroup> entityAssociations,
Dictionary <EntityModel, MethodGroup> extensionEntityAssociations)
{
// get source and target entities for association
// source is foreign key source table
// target is foreign key target table
if (!_entityBuilders.TryGetValue(association.Source, out var sourceBuilder) ||
!_entityBuilders.TryGetValue(association.Target, out var targetBuilder))
{
// data model misconfiguration (e.g. entity was removed from model, but not its associations)
throw new InvalidOperationException("Discovered association that connects tables, missing from current model.");
}
// build metadata keys for association
// (add fields used to define assocation to metadata)
BuildAssociationMetadataKey(association, false);
BuildAssociationMetadataKey(association, true);
// Type of assocation on source side.
// Nullable for nullable foreign key.
var sourceType = targetBuilder.Type.Type.WithNullability(association.SourceMetadata.CanBeNull);
// Type of association on target side.
var tagetType = sourceBuilder.Type.Type;
if (association.ManyToOne)
{
// for many-to-one assocations has collection type, defined by user preferences
if (_options.DataModel.AssociationCollectionAsArray)
{
tagetType = AST.ArrayType(tagetType, false);
}
else if (_dataModel.AssociationCollectionType != null)
{
tagetType = _dataModel.AssociationCollectionType.WithTypeArguments(tagetType);
}
else
{
// default type is IEnumerable
tagetType = WellKnownTypes.System.Collections.Generic.IEnumerable(tagetType);
}
}
else // if one-to-one association targets nullable columns, association is nullable
{
tagetType = tagetType.WithNullability(true);
}
// (if enabled) generate property-based association from source to target
if (association.Property != null)
{
BuildAssociationProperty(
entityAssociations,
association.Source,
sourceType,
association.Property,
association.SourceMetadata);
}
// (if enabled) generate property-based back-reference association from target to source
if (association.BackreferenceProperty != null)
{
BuildAssociationProperty(
entityAssociations,
association.Target,
tagetType,
association.BackreferenceProperty,
association.TargetMetadata);
}
// (if enabled) generate extension-based association from source to target
if (association.Extension != null)
{
BuildAssociationExtension(
extensionEntityAssociations,
extensionAssociations,
sourceBuilder,
targetBuilder,
sourceType,
association.Extension,
association.SourceMetadata,
association,
false);
}
// (if enabled) generate extension-based back-reference association from target to source
if (association.BackreferenceExtension != null)
{
BuildAssociationExtension(
extensionEntityAssociations,
extensionAssociations,
targetBuilder,
sourceBuilder,
tagetType,
association.BackreferenceExtension,
association.TargetMetadata,
association,
true);
}
}