/// <summary>
/// Find the ObjectContext from the given expression and cache it for future queries.
/// </summary>
protected Expression DiscoverContext(Expression expression)
{
Type type = expression is MemberExpression ? ((MemberExpression)expression).Type :
expression is MethodCallExpression && ((MethodCallExpression)expression).Object != null ?
((MethodCallExpression)expression).Object.Type : expression.Type;
if (type.IsGenericType && (type.GetGenericTypeDefinition() == typeof(ObjectQuery <>) ||
type.GetGenericTypeDefinition() == typeof(ObjectSet <>)))
{
// Example: "System.Data.Objects.ObjectSet`1[[B1.Utility.DatabaseSetup.ModelsSecond.AppConfigParameter, B1.Utility.DatabaseSetup, Version=1.13.1.0, Culture=neutral, PublicKeyToken=null]]"
string objectSetTypeName = type.FullName;
// Example: "B1.Utility.DatabaseSetup.ModelsSecond.AppConfigParameter"
string entityTypeName = ObjectContext.GetObjectType(type.GetGenericArguments()[0]).FullName;
string contextClassName = type.FullName; //?? ((MemberExpression) expression).Member.DeclaringType.FullName;
// Get the expression which can be evaluated to get the ObjectContext
Expression expressionToRun = expression is MemberExpression ? (MemberExpression)expression :
expression is MethodCallExpression ? ((MethodCallExpression)expression).Object : null;
// Ensure that the Context is stored
ObjectContext entityContext = EntityContextCache.Contexts.GetOrAdd(contextClassName,
() => { return(((ObjectQuery)Expression.Lambda(expressionToRun).Compile().DynamicInvoke()).Context ?? _defaultContext); });
// Ensure that the Storage meta data is loaded into cache
EntityContextCache.EnsureStorageMetaData(entityContext);
// Map the type names for the collection of entities and the entity to the context so that
// subsequent encounter of these types results in context look up
EntityContextCache.TypesToContexts.GetOrAdd(objectSetTypeName, () => { return(entityContext); });
EntityContextCache.TypesToContexts.GetOrAdd(entityTypeName, () => { return(entityContext); });
}
return(expression);
}
/// <summary>
/// Constructor for ContextVisitor takes the query expression.
/// </summary>
/// <param name="queryable">Query expression</param>
public ContextVisitor(IQueryable queryable)
{
if (queryable.GetType().IsGenericType&& (queryable.GetType().GetGenericTypeDefinition() == typeof(ObjectQuery <>) ||
queryable.GetType().GetGenericTypeDefinition() == typeof(ObjectSet <>)))
{
_defaultContext = ((ObjectQuery)queryable).Context;
EntityContextCache.EnsureStorageMetaData(_defaultContext);
}
// Visit the expression to discover if any other ObjectContext is used (cross-model query)
Visit(queryable.Expression);
}
/// <summary>
/// Get the QualifiedEntity which has the entity name and the schema name.
/// </summary>
/// <param name="dotNetEntityType">Entity type</param>
/// <returns>QualifiedEntity for the given entity type.</returns>
public QualifiedEntity GetQualifiedEntity(Type dotNetEntityType)
{
return(EntityContextCache.StorageMetaData.Get(
EntityContextCache.GetMappingTypeName(dotNetEntityType, _defaultContext)));
}
/// <summary>
/// Check if the entity already exists in the cache.
/// </summary>
/// <param name="dotNetEntityType">Entity type</param>
/// <returns>True if exists in the cache else false</returns>
public bool EntityExists(Type dotNetEntityType)
{
return(EntityContextCache.ExistsMappingTypeName(dotNetEntityType, _defaultContext));
}
