/// <summary>
/// Determines whether the <see cref="Expression" /> is rooted.
/// </summary>
/// <param name="expression">
/// The expression.
/// </param>
/// <param name="expectedRoot">
/// The expected root.
/// </param>
/// <param name="data">
/// The <see cref="QueryHelperData" /> info.
/// </param>
/// <returns>
/// True if the <see cref="Expression" /> is rooted; false otherwise.
/// </returns>
/// <exception cref="ArgumentNullException">
/// <paramref name="expression" /> is null.
/// </exception>
public static bool IsRooted
(
Expression expression,
string expectedRoot,
QueryHelperData data
)
{
if (expression == null)
{
throw new ArgumentNullException("expression");
}
string property = GetPropertyName(expression);
string[] splits = property.Split('.');
if (splits.Length <= 1)
{
return(false);
}
bool isRooted = splits[0] == expectedRoot ||
data.Aliases
.ContainsValue(splits[0]);
if (isRooted)
{
return(true);
}
string tempAlias = string.Join("_", splits.Take(splits.Length - 1));
return(data.Aliases
.ContainsValue(tempAlias));
}
/// <summary>
/// Generates new orders based on the underlying source by resolving the appropriate projections from the
/// given lambda expression.
/// </summary>
/// <param name="orderByStatements">
/// The order by statements.
/// </param>
/// <param name="projection">
/// The projection.
/// </param>
/// <param name="data">
/// The helper data.
/// </param>
/// <returns>
/// The new set of orders.
/// </returns>
/// <exception cref="ArgumentNullException">
/// <paramref name="orderByStatements" />, <paramref name="projection" /> or <paramref name="data" /> is
/// null.
/// </exception>
public static IEnumerable <OrderByStatement> GetSourceBasedOrdersFrom
(
IEnumerable <OrderByStatement> orderByStatements,
LambdaExpression projection,
QueryHelperData data
)
{
if (orderByStatements == null)
{
throw new ArgumentNullException("orderByStatements");
}
if (projection == null)
{
throw new ArgumentNullException("projection");
}
if (data == null)
{
throw new ArgumentNullException("data");
}
if (orderByStatements.All(x => x.IsBasedOnSource))
{
return(orderByStatements);
}
ProjectionHelper.GetProjection(projection, new HelperContext(data, projection, HelperType.Select));
var orders = new List <OrderByStatement>();
foreach (var statement in orderByStatements)
{
if (statement.IsBasedOnSource)
{
orders.Add(statement);
continue;
}
IProjection orderProjection;
bool foundMapping = data.Mappings
.TryGetValue(statement.Property, out orderProjection);
if (foundMapping)
{
var order = new OrderByStatement
{
IsBasedOnSource = true,
Order = new Order(orderProjection, statement.OrderAscending)
};
orders.Add(order);
}
}
return(orders);
}
/// <summary>
/// Creates a <see cref="IProjection" /> for the given <see cref="Expression" />.
/// </summary>
/// <param name="expression">
/// The expression.
/// </param>
/// <param name="data">
/// The <see cref="QueryHelperData" /> data.
/// </param>
/// <param name="type">
/// The <see cref="HelperType" /> type.
/// </param>
/// <returns>
/// The resolved <see cref="IProjection" /> instance.
/// </returns>
/// <exception cref="NotSupportedException">
/// The <see cref="Expression" /> could not be resolved as it may contain unsupported features or similar.
/// </exception>
public static IProjection GetProjection
(
LambdaExpression expression,
QueryHelperData data,
HelperType type = HelperType.Select
)
{
return(GetProjection(expression.Body, new HelperContext(data, expression.Parameters[0].Name, type)));
}
/// <summary>
/// Initializes a new instance of the <see cref="HelperContext" /> class.
/// </summary>
/// <param name="data">
/// The <see cref="QueryHelperData" /> data.
/// </param>
/// <param name="rootAlias">
/// The root alias.
/// </param>
/// <param name="type">
/// The <see cref="HelperType" />.
/// </param>
public HelperContext
(
QueryHelperData data,
string rootAlias,
HelperType type
)
{
Data = data;
RootAlias = rootAlias;
Type = type;
}
/// <summary>
/// Initializes a new instance of the <see cref="HelperContext" /> class.
/// </summary>
/// <param name="data">
/// The <see cref="QueryHelperData" /> data.
/// </param>
/// <param name="expression">
/// A lambda expression.
/// </param>
/// <param name="type">
/// The <see cref="HelperType" />.
/// </param>
public HelperContext
(
QueryHelperData data,
LambdaExpression expression,
HelperType type
)
: this(data, (string)null, type)
{
RootAlias = expression != null && expression.Parameters.Count > 0
? expression.Parameters[0].Name
: null;
}