Yozian.Extension 2.6.3

Useful Extension methods

You could take a look into test project to get examples with following list!

Extension methods of Type

• ExceptionExtension

  DumpDetail

• ExpressionExtension

  GetMemberName

• ICollectionExtension

  AddWhen

  RemoveWhen

• IDictionaryExtension

  SafeGet

• IEnumerableExtension

  ForEach

  FlattenToString

• IQueryableExtension

  WhereWhen

• ObjectExtension

  SafeToString

  ConvertAll

  ShallowClone

• StringExtension

  ToEnum

  LimitLength

  Repeat

• PaginationExtension

  ToPagination

  ToPaginationAsync

Take IQueryable Extension method as example

conditional query where closure

The example shows the extension method WhereWhen eliminate if statement block.

The constrain applied only when the condition matched, so that you could achieve dynamic query easily!

var books = await this.dbContext.Book
                .Where(x => x.Name.Equals(request.Name))
                .WhereWhen(
                    !string.IsNullOrEmpty(request.Category),
                    x => x.Category.Equals(request.Category)
                )
                .WhereWhen(
                    request.PublishDate.HasValue,
                    x => x.PublishDate.Equals(request.PublishDate)
                )
                .ToListAsync();

for old school way, would have lots of if statement block

var query = this.dbContext.Book
                .Where(x => x.Name.Equals(request.Name));

if(!string.IsNullOrEmpty(request.Category)){
    query = query.Where(x => x.Category.Equals(request.Category))
}

if(request.PublishDate.HasValue){
    query = query.Where(x => x.PublishDate.Equals(request.PublishDate))
}

var books = await query.ToListAsync();

IQueryable Pagination

• An Extension method for IQueryable<T> interface
• Could apply on EntityFramework DbSet<T> query (Any implementation of IQueryable<T>)

        var count = 10;
        var size = 3;
        var source = Enumerable
            .Range(1, count)
            .AsQueryable();

        Pageable<int> result = source.ToPagination(1, size);

        // Async 
        Pageable<int> result = await source.ToPaginationAsync(1, size);

Apply converter

        var count = 10;
        var size = 3;
        var source = Enumerable
            .Range(1, count)
            .AsQueryable();

        Pageable<int, string> result = source.ToPagination(1, size, x => x.ToString());

        // Async 
        Pageable<int, string> result = await source.ToPaginationAsync(1, size, x => x.ToString());

Fetch next page for the same queryable source

        var count = 10;
        var size = 3;
        var source = Enumerable
            .Range(1, count)
            .AsQueryable();

        Pageable<int, string> result = source.ToPagination(1, size, x => x.ToString());

        do
        {
            // process records here
            result.Records.ForEach(it =>
            {
                // do somthing

            });

            result.FetchNextPage();

        }
        while (result.HasNextPage);
      

Fetch next page for the same queryable source

        var count = 32;
        var size = 3;
        var source = Enumerable
            .Range(1, count)
            .AsQueryable();
        var currentPage = 3;

        var result = source.ToPagination(currentPage, size);

        var pageSize = 5;

        // converte to Page<T>, including navigation info.
        Page<int> page = result.ToPage(pageSize);
    
        // also provide tranform method to map records
        Page<string> page = result.ToPage(pageSize, x => x.ToString());


        // dump Page<int> 
        {
          "TotalCount": 32,
          "PageCount": 11,
          "CurrentPage": 3,
          "Size": 3,
          "Records": [
            7,
            8,
            9
          ],
          "PageSize": 5,
          "HasPreviosPages": false,
          "HasNextPages": true,
          "PreviosLastPageNo": 1,
          "NextStartPageNo": 6,
          "NavigationPages": [
            1,
            2,
            3,
            4,
            5
          ]
        }