HLCores.Extensions.Linq 2.0.0

HLCores.Extensions.Linq

HLCores.Extensions.Linq is custom functions linq.

Features

• FullOuterJoin.
• FullOuterGroupJoin.
• IOrderedQueryable <TSource> SortByDescending <TSource>(this IQueryable <TSource> source, stringpropertyName).
• IOrderedQueryable <TSource> SortBy <TSource>(this IQueryable <TSource> source, stringpropertyName).
• IOrderedQueryable <TSource> SortBy <TSource>(this IQueryable <TSource> source, List <SortParam> sortParams).
• IOrderedEnumerable <TSource> SortBy <TSource>(this IEnumerable <TSource> source, stringpropertyName).
• IOrderedEnumerable <TSource> SortByDescending <TSource>(this IEnumerable <TSource> source, stringpropertyName).
• IOrderedEnumerable <TSource> SortBy <TSource>(this IEnumerable <TSource> source, List <SortParam> sortParams).

Usage

1. FullOuterJoin & FullOuterGroupJoin

Joining is a term borrowed from relational database design:

• A join will repeat elements from a as many times as there are elements in b with corresponding key (i.e.: nothing if b were empty). Database lingo calls this inner join .
• An outer join includes elements from a for which no corresponding element exists in b. (i.e.: even results if b were empty). This is usually referred to as left join .
• A full outer join includes records from a as well as b if no corresponding element exists in the other. (i.e. even results if a were empty)

Something not usually seen in RDBMS is a group join:

• A group join , does the same as described above, but instead of repeating elements from a for multiple corresponding b, it groups the records with corresponding keys. This is often more convenient when you wish to enumerate through 'joined' records, based on a common key.

See also GroupJoin which contains some general background explanations as well.

Exam:

var result = tableA.FullOuterJoin(
    tableB,
    a => a.Id,             // Key selector for TableA
    b => b.ForeignKeyId,   // Key selector for TableB
    (a, b, key) => new     // Result projection
    {
        TableA = a,
        TableB = b,
        Key = key
    }
);

var result = tableA.FullOuterGroupJoin(
    tableB,
    a => a.Id,             // Key selector for TableA
    b => b.ForeignKeyId,   // Key selector for TableB
    (a, b, key) => new     // Result projection
    {
        TableA = a,
        TableB = b,
        Key = key
    },
    default(TableA),       // Default value for TableA
    default(TableB)        // Default value for TableB
);

2. SortBy

Sorts the elements of a sequence in ascending order according to a string key required must exist in TSource

Exam:

public async Task<PaginationUtility<DistrictDto>> GetDataPagination(PaginationParam pagination, DistrictParam param)
{
    var predicate = PredicateBuilder.New<District>(true);
    if (!string.IsNullOrWhiteSpace(param.Keyword))
    {
        string keyword = param.Keyword.ToLower();
        predicate.And(x => x.Title.ToLower().Contains(keyword) || x.Code.ToLower().Contains(keyword));
    }
    if (param.ProvinceId is not null)
    predicate.And(x => x.ProvinceId == param.ProvinceId);

    var data = _context.District.Where(predicate)
        .Include(x => x.Province)
        .Map<DistrictDto>()
        .SortBy("UpdateTime").AsNoTracking();

    return await PaginationUtility<DistrictDto>.CreateAsync(data, pagination.PageNumber, pagination.PageSize);
}

3. SortByDescending

Sorts the elements of a sequence in descending order according to a string key required must exist in TSource.

Exam:

public async Task<PaginationUtility<DistrictDto>> GetDataPagination(PaginationParam pagination, DistrictParam param)
{
    var predicate = PredicateBuilder.New<District>(true);
    if (!string.IsNullOrWhiteSpace(param.Keyword))
    {
        string keyword = param.Keyword.ToLower();
        predicate.And(x => x.Title.ToLower().Contains(keyword) || x.Code.ToLower().Contains(keyword));
    }
    if (param.ProvinceId is not null)
        predicate.And(x => x.ProvinceId == param.ProvinceId);

    var data = _context.District.Where(predicate)
        .Include(x => x.Province)
        .Map<DistrictDto>()
        .SortByDescending("UpdateTime").AsNoTracking();

    return await PaginationUtility<DistrictDto>.CreateAsync(data, pagination.PageNumber, pagination.PageSize);
}

4. SortBy (sort params)

Sorts the elements of a sequence in ascending/descending order according by list sort param.

Exam:

public async Task<PaginationUtility<DistrictDto>> GetDataPagination(PaginationParam pagination, DistrictParam param)
{
    var predicate = PredicateBuilder.New<District>(true);
    if (!string.IsNullOrWhiteSpace(param.Keyword))
    {
        string keyword = param.Keyword.ToLower();
        predicate.And(x => x.Title.ToLower().Contains(keyword) || x.Code.ToLower().Contains(keyword));
    }
    if (param.ProvinceId is not null)
        predicate.And(x => x.ProvinceId == param.ProvinceId);

    var data = _context.District.Where(predicate)
        .Include(x => x.Province)
        .Map<DistrictDto>()
        .SortBy(new List<SortParam>()
        {
            new() {
                Direction = SortDirection.Ascending,
                PropertyName = "ProvinceCode"
            },
            new() {
                Direction = SortDirection.Descending,
                PropertyName = "Code"
            }
        }).AsNoTracking();

    return await PaginationUtility<DistrictDto>.CreateAsync(data, pagination.PageNumber, pagination.PageSize);
}