59 lines
2.6 KiB
C#
59 lines
2.6 KiB
C#
using JSMR.Application.Common.Search;
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using Microsoft.EntityFrameworkCore;
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using System.Linq.Expressions;
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namespace JSMR.Infrastructure.Common.Queries;
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public abstract class SearchProvider<TItem, TCriteria, TSortField, TBaseQuery> : ISearchProvider<TItem, TCriteria, TSortField>
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where TCriteria : new()
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where TSortField : struct, Enum
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{
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public async Task<SearchResult<TItem>> SearchAsync(SearchOptions<TCriteria, TSortField> options, CancellationToken cancellationToken = default)
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{
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IQueryable<TBaseQuery> baseQuery = GetBaseQuery();
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IQueryable<TBaseQuery> filteredQuery = ApplyFilters(baseQuery, options.Criteria);
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int total = await filteredQuery.CountAsync(cancellationToken);
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IOrderedQueryable<TBaseQuery> orderedQuery = ApplySorting(filteredQuery, options.SortOptions);
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IOrderedQueryable<TItem> selectQuery = GetSelectQuery(orderedQuery);
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TItem[] items = await selectQuery
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.Skip((options.PageNumber - 1) * options.PageSize)
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.Take(options.PageSize)
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.ToArrayAsync(cancellationToken);
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return new SearchResult<TItem>()
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{
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Items = items,
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TotalItems = total
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};
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}
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protected abstract IQueryable<TBaseQuery> GetBaseQuery();
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protected abstract IQueryable<TBaseQuery> ApplyFilters(IQueryable<TBaseQuery> query, TCriteria criteria);
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private IOrderedQueryable<TBaseQuery> ApplySorting(IQueryable<TBaseQuery> query, SortOption<TSortField>[] sortOptions)
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{
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IOrderedQueryable<TBaseQuery>? ordered = null;
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for (int i = 0; i < sortOptions.Length; i++)
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{
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var (field, direction) = (sortOptions[i].Field, sortOptions[i].Direction);
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bool isDescending = direction == SortDirection.Descending;
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IOrderedQueryable<TBaseQuery> applyFirst(Expression<Func<TBaseQuery, object>> selector) => isDescending ? query.OrderByDescending(selector) : query.OrderBy(selector);
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IOrderedQueryable<TBaseQuery> applyNext(Expression<Func<TBaseQuery, object>> selector) => isDescending ? ordered!.ThenByDescending(selector) : ordered!.ThenBy(selector);
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Expression<Func<TBaseQuery, object>> selector = GetSortExpression(field);
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ordered = (i == 0) ? applyFirst(selector) : applyNext(selector);
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}
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return ordered ?? GetDefaultSortExpression(query);
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}
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protected abstract Expression<Func<TBaseQuery, object>> GetSortExpression(TSortField field);
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protected abstract IOrderedQueryable<TBaseQuery> GetDefaultSortExpression(IQueryable<TBaseQuery> query);
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protected abstract IOrderedQueryable<TItem> GetSelectQuery(IOrderedQueryable<TBaseQuery> query);
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} |