99 lines
3.4 KiB
C#
99 lines
3.4 KiB
C#
using Dapper;
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using Femto.Modules.Blog.Domain.Posts.Commands.GetPosts.Dto;
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using Femto.Modules.Blog.Infrastructure.DbConnection;
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using MediatR;
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namespace Femto.Modules.Blog.Domain.Posts.Commands.GetPosts;
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public class GetPostsQueryHandler(IDbConnectionFactory connectionFactory)
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: IRequestHandler<GetPostsQuery, GetPostsQueryResult>
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{
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public async Task<GetPostsQueryResult> Handle(
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GetPostsQuery query,
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CancellationToken cancellationToken
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)
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{
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using var conn = connectionFactory.GetConnection();
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if (query.Username is not null && query.AuthorGuid is not null)
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throw new ArgumentException(
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"Cannot specify both username and authorGuid",
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nameof(query)
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);
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var orderBy = query.Direction is GetPostsDirection.Backward ? "desc" : "asc";
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var pageFilter = query.Direction is GetPostsDirection.Backward ? "<=" : ">=";
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// lang=sql
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var sql = $$"""
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with page as (
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select blog.post.*, blog.author.username as Username, blog.author.id as AuthorId
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from blog.post
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inner join blog.author on blog.author.id = blog.post.author_id
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where (@username is null or blog.author.username = @username)
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and (@authorGuid is null or blog.author.id = @authorGuid)
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and (@cursor is null or blog.post.id {{pageFilter}} @cursor)
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order by blog.post.id {{orderBy}}
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limit @amount
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)
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select
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page.id as PostId,
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page.content as Content,
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blog.post_media.url as MediaUrl,
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page.created_on as CreatedAt,
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page.Username,
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page.AuthorId
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from page
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left join blog.post_media on blog.post_media.post_id = page.id
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order by page.id {{orderBy}}
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""";
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var result = await conn.QueryAsync<QueryResult>(
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sql,
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new
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{
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username = query.Username,
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authorGuid = query.AuthorGuid,
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cursor = query.From,
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// load an extra one to take for the curst
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amount = query.Amount + 1,
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}
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);
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var rows = result.ToList();
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var posts = rows.GroupBy(row => row.PostId)
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.Select(group =>
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{
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var postId = group.Key;
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var post = group.First();
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var media = group
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.Select(row => row.MediaUrl)
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.OfType<string>()
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.Select(url => new PostMediaDto(new Uri(url)))
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.ToList();
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return new PostDto(
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postId,
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post.Content,
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media,
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post.CreatedAt,
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new PostAuthorDto(post.AuthorId, post.Username)
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);
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})
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.ToList();
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var next = rows.Count >= query.Amount ? rows.LastOrDefault()?.PostId : null;
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return new GetPostsQueryResult(posts, next);
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}
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internal class QueryResult
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{
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public Guid PostId { get; set; }
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public string Content { get; set; }
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public string? MediaUrl { get; set; }
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public DateTime CreatedAt { get; set; }
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public Guid AuthorId { get; set; }
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public string Username { get; set; }
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}
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}
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