/// <summary>
/// Tries to handle the current segment as a key property value.
/// </summary>
/// <param name="segmentText">The segment text.</param>
/// <param name="previous">The previous segment.</param>
/// <param name="urlConvention">The current url convention for the server.</param>
/// <param name="keySegment">The key segment that was created if the segment could be interpreted as a key.</param>
/// <returns>Whether or not the segment was interpreted as a key.</returns>
internal static bool TryHandleSegmentAsKey(string segmentText, IPathSegment previous, UrlConvention urlConvention, out IPathSegment keySegment)
{
DebugUtils.CheckNoExternalCallers();
Debug.Assert(previous != null, "previous != null");
Debug.Assert(urlConvention != null, "urlConvention != null");
keySegment = null;
// If the current convention is not keys-as-segments, then this does not apply.
if (!urlConvention.GenerateKeyAsSegment)
{
return(false);
}
// If the current identifier was preceeded by a '$' segment, then do not treat it as a key.
if (previous.IsEscapeMarker)
{
return(false);
}
// Keys only apply to collections, so if the prior segment is already a singleton, do not treat this segment as a key.
if (previous.SingleResult)
{
return(false);
}
// System segments (ie '$count') are never keys.
if (IsSystemSegment(segmentText))
{
return(false);
}
// If the previous type is not an entity collection type
// TODO: collapse this and SingleResult.
IEdmEntityType targetEntityType;
if (previous.TargetEdmType == null || !previous.TargetEdmType.IsEntityOrEntityCollectionType(out targetEntityType))
{
return(false);
}
// If the resource type has more than 1 key property, then do not treat the segment as a key.
var keyProperties = targetEntityType.Key().ToList();
if (keyProperties.Count > 1)
{
return(false);
}
// At this point it must be treated as a key, so fail if it is malformed.
Debug.Assert(keyProperties.Count == 1, "keyProperties.Count == 1");
keySegment = CreateKeySegment(previous, KeyInstance.FromSegment(segmentText));
return(true);
}
