public static string GetAll(
PagingQueryParams paging = null,
SortingQueryParams sorting = null,
FilterQueryParams filtering = null)
{
var baseUrl = $"{BaseUrl}";
var queryParams = new Dictionary <string, string>();
if (paging != null)
{
queryParams.Add(nameof(PagingQueryParams.Page), $"{paging.Page}");
queryParams.Add(nameof(PagingQueryParams.PageSize), $"{paging.PageSize}");
}
if (filtering != null)
{
queryParams.Add(nameof(SortingQueryParams.SortQueryExpression), $"{sorting.SortQueryExpression}");
}
if (sorting != null)
{
queryParams.Add(nameof(FilterQueryParams.SearchTerm), $"{filtering.SearchTerm}");
}
return(QueryHelpers.AddQueryString(baseUrl, queryParams));
}
public async Task <IActionResult> GetAll(
[FromQuery] PagingQueryParams pagingParams,
[FromQuery] SortingQueryParams sortingParams,
[FromQuery] FilterQueryParams filteringParams,
CancellationToken cancellationToken = default)
{
return(Ok(await Mediator.Send(new GetItemsQuery(pagingParams, sortingParams, filteringParams),
cancellationToken)));
}
/// <summary>
/// Builds and retrieves Item filter function
/// </summary>
/// <param name="parameters">Describes search term for name, description or category name for item</param>
/// <returns>Expression which is used in LINQ to SQL on database level for filtering</returns>
internal Expression <Func <Item, bool> > GetFilterFn(FilterQueryParams parameters)
{
if (string.IsNullOrWhiteSpace(parameters.SearchTerm))
{
return(null);
}
// normalize search term
var searchTerm = parameters.SearchTerm.Trim().ToLower();
// define expression input item => item....
var input = Expression.Parameter(typeof(Item));
// create expression constant to be used
var searchTermConstant = Expression.Constant(searchTerm);
// define all conditions
Expression <Func <Item, string, bool> > nameMatchDelegate = (item, value) => !string.IsNullOrWhiteSpace(item.Name) && item.Name.Trim().ToLower().Contains(value);
var nameMatchInvoke = Expression.Invoke(nameMatchDelegate, input, searchTermConstant);
Expression <Func <Item, string, bool> > descriptionMatchDelegate = (item, value) => !string.IsNullOrWhiteSpace(item.Description) && item.Description.Trim().ToLower().Contains(value);
var descriptionMatchInvoke = Expression.Invoke(descriptionMatchDelegate, input, searchTermConstant);
Expression <Func <Item, string, bool> > categoryMatchDelegate = (item, value) => item.Category != null && !string.IsNullOrWhiteSpace(item.Category.Name) && item.Category.Name.Trim().ToLower().Contains(value);
var categoryMatchInvoke = Expression.Invoke(categoryMatchDelegate, input, searchTermConstant);
var conditions = new List <Expression> {
nameMatchInvoke, descriptionMatchInvoke, categoryMatchInvoke
};
// item => nameMatch(item) || descriptionMatch(item) || categoryMatch(item)
var body = conditions
.Skip(1)
.Aggregate(
seed: conditions.FirstOrDefault(),
func: Expression.Or);
return(Expression.Lambda <Func <Item, bool> >(body, input));
}
public GetItemsQuery(PagingQueryParams pagingParams, SortingQueryParams sortingParams, FilterQueryParams filteringParams)
{
PagingParams = pagingParams;
SortingParams = sortingParams;
FilteringParams = filteringParams;
}
