private IEnumerable <T> Query(ResourceQuery query, CancellationToken cancellationToken)
{
IEnumerable <T> results = _service.Get(query, cancellationToken);
//
// "Developers who want to know the full number of records across all pages, MAY include the query parameter
// $count=true to tell the server to include the count of items in the response.
//
if (query.TotalRows.HasValue)
{
HttpContext.Items.TryAdd(Constants.CountResultContextKey, query.TotalRows.Value);
}
HttpContext.Items.TryAdd(Constants.QueryContextKey, query);
return(results);
}
private static bool BuildResourceQuery(IResourceDataService service, HttpContext context, IOptions <ApiOptions> options, out ResourceQuery query)
{
query = new ResourceQuery();
if (service.SupportsSorting && context.Items.TryGetValue(Constants.SortContextKey, out var sortMap) &&
sortMap != null)
{
query.Sorting = (List <(AccessorMember, SortDirection)>)sortMap;
context.Items.Remove(Constants.SortContextKey);
}
if (service.SupportsFiltering && context.Items.TryGetValue(Constants.FilterOperationContextKey, out var filterValue) &&
filterValue is List <(string, FilterOperator, string?)> filters)
{
query.Filters = filters;
}
if (service.SupportsCount)
{
// We don't check whether the request asked for counting, because we need counting to determine next page results either way,
// so we'll attempt to always count the total records if it's supported.
query.CountTotalRows = true;
context.Items.Remove(Constants.CountContextKey);
}
if (service.SupportsSkip && context.Items.TryGetValue(Constants.SkipOperationContextKey, out var skipValue) &&
skipValue is int skip)
{
query.PageOffset = skip;
context.Items.Remove(Constants.SkipOperationContextKey);
}
if (service.SupportsTop & context.Items.TryGetValue(Constants.TopOperationContextKey, out var topValue) &&
topValue is int top)
{
//
// "Note that client-driven paging does not preclude server-driven paging.
// If the page size requested by the client is larger than the default page size
// supported by the server, the expected response would be the number of results specified by the client,
// paginated as specified by the server paging settings."
//
query.PageSize = top;
context.Items.Remove(Constants.TopOperationContextKey);
}
if (service.SupportsMaxPageSize &&
context.Items.TryGetValue(Constants.MaxPageSizeContextKey, out var maxPageSizeValue) &&
maxPageSizeValue is int maxPageSize)
{
query.MaxPageSize = maxPageSize;
context.Items.Remove(Constants.MaxPageSizeContextKey);
}
if (service.SupportsShaping && context.Items.TryGetValue(Constants.ShapingOperationContextKey, out var shapingValue) &&
shapingValue is List <string> include)
{
query.Fields = include;
context.Items.Remove(Constants.ShapingOperationContextKey);
}
// If no $skip is provided, assume the query is for the first page
query.PageOffset ??= 0;
//
// "Clients MAY request server-driven paging with a specific page size by specifying a $maxpagesize preference.
// The server SHOULD honor this preference if the specified page size is smaller than the server's default page size."
//
// Interpretation:
// - If the client specifies $top, use $top as the page size.
// - If the client omits $top but specifies $maxpagesize, use the smaller of $maxpagesize and the server's default page size.
if (!query.PageSize.HasValue)
{
if (query.MaxPageSize.HasValue && query.MaxPageSize.Value < options.Value.Paging.MaxPageSize.DefaultPageSize)
{
query.PageSize = query.MaxPageSize.Value;
}
else
{
query.PageSize = options.Value.Paging.MaxPageSize.DefaultPageSize;
}
}
// If we still don't have a page size, assume the query is for the default page size
if (!query.PageSize.HasValue || query.PageSize.Value == 0)
{
query.PageSize = options.Value.Paging.MaxPageSize.DefaultPageSize;
}
//
// "If the server can't honor $top and/or $skip,
// the server MUST return an error to the client informing about it instead of just ignoring the query options.
// This will avoid the risk of the client making assumptions about the data returned."
//
if (query.PageSize.Value > options.Value.Paging.MaxPageSize.MaxPageSize)
{
return(false);
}
if (service.SupportsSearch && context.Items.TryGetValue(Constants.SearchOperationContextKey, out var searchValue) &&
searchValue is string searchQuery)
{
query.SearchQuery = searchQuery;
context.Items.Remove(Constants.SearchOperationContextKey);
}
return(true);
}