/// <summary>
/// Specifies additional related entities to include in serialized output of a Coalesce custom data source.
/// The specified entities must have already been loaded into the context that was provided for the data source.
/// to be included is specified starting with the type of entity being queried (TEntity).
/// If you wish to include additional types based on the navigation properties of
/// the type being included, then chain a call to .ThenIncluded(prop => prop.Child)
/// after this call.
///
/// The purpose of this is to allow loading subsets of navigation properties without neccesarily loading the entire contents of the navigation property.
/// </summary>
/// <typeparam name="TEntity"></typeparam>
/// <typeparam name="TProperty"></typeparam>
/// <param name="query"></param>
/// <param name="expr">An expression which returns the navigation property that should be included in the data source's output.</param>
/// <returns></returns>
public static IIncludedSeparatelyQueryable <TEntity, TProperty> IncludedSeparately <TEntity, TProperty>(
this IQueryable <TEntity> query,
Expression <Func <TEntity, TProperty> > expr) where TEntity : class
{
var provider = query.Provider as IncludableQueryProvider;
if (provider == null)
{
query = query.CaptureSeparateIncludes();
provider = query.Provider as IncludableQueryProvider;
}
IncludeTree tail;
var body = ((MemberExpression)expr.Body);
var head = IncludeTree.ParseMemberExpression(body, out tail);
// Add the head of this expression to the root includetree for the query.
tail = provider.IncludeTree.AddLinearChild(head);
return(new IncludedSeparatelyQueryable <TEntity, TProperty>(query)
{
IncludeTree = tail
});
}
public static IncludeTree GetIncludeTree(this IQueryable queryable, string rootName = null)
{
if (!(queryable.Provider is IncludableQueryProvider) && !(queryable.Provider is EntityQueryProvider))
{
throw new ArgumentException(
$"Can't get an IncludeTree from an IQueryable with an IQueryProvider of type {queryable.Provider.GetType().Name}. "
+ "Try using .IncludedSeparately(...) and .ThenIncluded(...) to capture includes.");
}
var expression = queryable.Expression;
IncludeTree root = (queryable.Provider as IncludableQueryProvider)?.IncludeTree ?? new IncludeTree {
PropertyName = rootName
};
IncludeTree currentNode = null;
// When we get to the root of the queryable, it won't be a MethodCallExpression.
while (expression is MethodCallExpression)
{
// callExpr.Arguments[0] is the entire previous query.
// callExpr.Arguments[1] is the lambda for the property specifier
var callExpr = expression as MethodCallExpression;
if (callExpr.Method.Name == nameof(EntityFrameworkQueryableExtensions.Include) ||
callExpr.Method.Name == nameof(EntityFrameworkQueryableExtensions.ThenInclude))
{
// I'm like a wizard with all these casts.
var body = ((MemberExpression)((LambdaExpression)((UnaryExpression)callExpr.Arguments[1]).Operand).Body);
IncludeTree tail;
var head = IncludeTree.ParseMemberExpression(body, out tail);
// If we had a child from a ThenInclude, add it to the tail of this node.
if (currentNode != null)
{
tail.AddChild(currentNode);
}
// Save the head of this expression in case we're parsing a ThenInclude.
currentNode = head;
if (callExpr.Method.Name == nameof(EntityFrameworkQueryableExtensions.Include))
{
// Finally, add the current node to the root, since a .Include doesn't have parents.
root.AddChild(head);
currentNode = null;
}
}
expression = callExpr.Arguments[0];
}
return(root);
}
public static IIncludedSeparatelyQueryable <TEntity, TProperty> ThenIncluded <TEntity, TPreviousProperty, TProperty>(
this IIncludedSeparatelyQueryable <TEntity, IEnumerable <TPreviousProperty> > source,
Expression <Func <TPreviousProperty, TProperty> > navigationPropertyPath)
where TEntity : class
{
IncludeTree tail;
var body = ((MemberExpression)navigationPropertyPath.Body);
var head = IncludeTree.ParseMemberExpression(body, out tail);
// Merge in the head of this tree as a child of the parent tree.
tail = source.IncludeTree.AddLinearChild(head);
return(new IncludedSeparatelyQueryable <TEntity, TProperty>(source)
{
IncludeTree = tail
});
}
