2.5.7 MongoDB — API实现

• 问题查询单个实现
• 问题查询列表实现
• 问题跨集合查询实现
• 问题创建实现
• 问题更新实现
• 问题回答实现
• 问题评论实现
• 问题投票实现
• 回答实现

QuestionController

namespace LighterApi.Controller
{
    [ApiController]
    [Route("api/[controller]")]
    public class QuestionController : ControllerBase
    {
        private readonly IMongoCollection<Question> _questionCollection;

        private readonly IMongoCollection<Vote> _voteCollection;

        private readonly IMongoCollection<Answer> _answerCollection;

        public QuestionController(IMongoClient mongoClient)
        {
            var database = mongoClient.GetDatabase("lighter");

            _questionCollection = database.GetCollection<Question>("questions");
            _voteCollection = database.GetCollection<Vote>("votes");
            _answerCollection = database.GetCollection<Answer>("answers");
        }
    }
}

问题查询单个实现

linq 查询

[HttpGet]
[Route("{id}")]
public async Task<ActionResult<Question>> GetAsync(string id, CancellationToken cancellationToken)
{
    var question = await _questionCollection.AsQueryable()
        .FirstOrDefaultAsync(q => q.Id == id, cancellationToken: cancellationToken);
    if (question == null)
        return NotFound();

    return Ok(question);
}

mongo 查询表达式

var filter = Builders<Question>.Filter.Eq(q => q.Id, id);
await _questionCollection.Find(filter).FirstOrDefaultAsync(cancellationToken);

构造空查询条件的表达式

var filter = string.IsNullOrEmpty(id)
    ? Builders<Question>.Filter.Empty
    : Builders<Question>.Filter.Eq(q => q.Id, id);

多段拼接 filter

var filter2 = Builders<Question>.Filter.And(filter, Builders<Question>.Filter.Eq(q => q.TenantId , "001"));

问题查询列表实现

• 数据 AnyIn查询
• 排序 sort : StirngFieldDefinition
• 分页 skip, limit

[HttpGet]
public async Task<ActionResult<List<Question>>> GetListAsync([FromQuery] List<string> tags,
    CancellationToken cancellationToken, [FromQuery] string sort = "createdAt", [FromQuery] int skip = 0,
    [FromQuery] int limit = 10)
{
    //// linq 查询
    //await _questionCollection.AsQueryable().Where(q => q.ViewCount > 10)
    //    .ToListAsync(cancellationToken: cancellationToken);

    var filter = Builders<Question>.Filter.Empty;

    if (tags != null && tags.Any())
    {
        filter = Builders<Question>.Filter.AnyIn(q => q.Tags, tags);
    }

    var sortDefinition = Builders<Question>.Sort.Descending(new StringFieldDefinition<Question>(sort));

    var result = await _questionCollection
        .Find(filter)
        .Sort(sortDefinition)
        .Skip(skip)
        .Limit(limit)
        .ToListAsync(cancellationToken: cancellationToken);

    return Ok(result);
}

问题跨集合查询实现

[HttpGet]
[Route("{id}/answers")]
public async Task<ActionResult> GetWithAnswerAsync(string id, CancellationToken cancellationToken)
{
    // linq 查询
    var query = from question in _questionCollection.AsQueryable()
                where question.Id == id
                join a in _answerCollection.AsQueryable() on question.Id equals a.QuestionId into answers
                select new { question, answers };

    var result = await query.FirstOrDefaultAsync(cancellationToken);

    if (result == null)
        return NotFound();

    return Ok(result);
}

问题创建实现

[HttpPost]
public async Task<ActionResult<Question>> CreateAsync([FromBody] Question question,
    CancellationToken cancellationToken)
{
    question.Id = Guid.NewGuid().ToString();
    await _questionCollection.InsertOneAsync(question, new InsertOneOptions {BypassDocumentValidation = false},
        cancellationToken);
    return StatusCode((int) HttpStatusCode.Created, question);
}

问题更新实现

[HttpPatch]
[Route("{id}")]
public async Task<ActionResult> UpdateAsync([FromRoute] string id, [FromBody] QuestionUpdateRequest request,
    CancellationToken cancellationToken)
{
    if (string.IsNullOrEmpty(request.Summary))
        throw new ArgumentNullException(nameof(request.Summary));

    var filter = Builders<Question>.Filter.Eq(q => q.Id, id);

    var update = Builders<Question>.Update
        .Set(q => q.Title, request.Title)
        .Set(q => q.Content, request.Content)
        .Set(q => q.Tags, request.Tags)
        .Push(q => q.Comments, new Comment { Content = request.Summary, CreatedAt = DateTime.Now });

    await _questionCollection.UpdateOneAsync(filter, update, cancellationToken: cancellationToken);

    return Ok();
}

使用拼接的方式构建表达式

var updateFieldList = new List<UpdateDefinition<Question>>();

if (!string.IsNullOrWhiteSpace(request.Title))
    updateFieldList.Add(Builders<Question>.Update.Set(q => q.Title, request.Title));

if (!string.IsNullOrWhiteSpace(request.Content))
    updateFieldList.Add(Builders<Question>.Update.Set(q => q.Content, request.Content));

if (request.Tags != null && request.Tags.Any())
    updateFieldList.Add(Builders<Question>.Update.Set(q => q.Tags, request.Tags));

updateFieldList.Add(Builders<Question>.Update.Push(q => q.Comments,
    new Comment {Content = request.Summary, CreatedAt = DateTime.Now}));

var update = Builders<Question>.Update.Combine(updateFieldList);

问题回答实现

[HttpPost]
[Route("{id}/answer")]
public async Task<ActionResult<Answer>> AnswerAsync([FromRoute] string id, [FromBody] AnswerRequest request,
    CancellationToken cancellationToken)
{
    var answer = new Answer {QuestionId = id, Content = request.Content, Id = Guid.NewGuid().ToString()};
    _answerCollection.InsertOneAsync(answer, cancellationToken);

    var filter = Builders<Question>.Filter.Eq(q => q.Id, id);
    var update = Builders<Question>.Update.Push(q => q.Answers, answer.Id);

    await _questionCollection.UpdateOneAsync(filter, update, null, cancellationToken);

    return Ok();
}

问题评论实现

[HttpPost]
[Route("{id}/comment")]
public async Task<ActionResult> CommentAsync([FromRoute] string id, [FromBody] CommentRequest request,
    CancellationToken cancellationToken)
{
    var filter = Builders<Question>.Filter.Eq(q => q.Id, id);
    var update = Builders<Question>.Update.Push(q => q.Comments,
        new Comment {Content = request.Content, CreatedAt = DateTime.Now});

    await _questionCollection.UpdateOneAsync(filter, update, null, cancellationToken);

    return Ok();
}

问题投票实现

[HttpPost]
[Route("{id}/up")]
public async Task<ActionResult> UpAsync([FromBody] string id, CancellationToken cancellationToken)
{
    var vote = new Vote
    {
        Id = Guid.NewGuid().ToString(),
        SourceType = ConstVoteSourceType.Question,
        SourceId = id,
        Direction = EnumVoteDirection.Up
    };

    await _voteCollection.InsertOneAsync(vote, cancellationToken);

    var filter = Builders<Question>.Filter.Eq(q => q.Id, id);
    var update = Builders<Question>.Update.Inc(q => q.VoteCount, 1).AddToSet(q => q.VoteUps, vote.Id);
    await _questionCollection.UpdateOneAsync(filter, update);

    return Ok();
}

[HttpPost]
[Route("{id}/down")]
public async Task<ActionResult> DownAsync([FromBody] string id, CancellationToken cancellationToken)
{
    var vote = new Vote
    {
        Id = Guid.NewGuid().ToString(),
        SourceType = ConstVoteSourceType.Question,
        SourceId = id,
        Direction = EnumVoteDirection.Down
    };

    await _voteCollection.InsertOneAsync(vote, cancellationToken);

    var filter = Builders<Question>.Filter.Eq(q => q.Id, id);
    var update = Builders<Question>.Update.Inc(q => q.VoteCount, -1).AddToSet(q => q.VoteDowns, vote.Id);
    await _questionCollection.UpdateOneAsync(filter, update);

    return Ok();
}

回答实现

namespace LighterApi.Controller
{
    [ApiController]
    [Route("api/[controller]")]
    public class AnswerController : ControllerBase
    {
        private readonly IMongoCollection<Vote> _voteCollection;

        private readonly IMongoCollection<Answer> _answerCollection;

        public AnswerController(IMongoClient mongoClient)
        {
            var database = mongoClient.GetDatabase("lighter");

            _voteCollection = database.GetCollection<Vote>("votes");
            _answerCollection = database.GetCollection<Answer>("answers");
        }

        [HttpGet]
        public async Task<ActionResult<Answer>> GetListAsync([FromQuery] string questionId, CancellationToken cancellationToken)
        {
            var list = await _answerCollection.AsQueryable().Where(a => a.QuestionId == questionId)
                .ToListAsync(cancellationToken);
            return Ok(list);
        }

        [HttpPatch]
        [Route("{id}")]
        public async Task<ActionResult> UpdateAsync(string id, string content, string summary,
            CancellationToken cancellationToken)
        {
            var filter = Builders<Answer>.Filter.Eq(q => q.Id, id);

            var update = Builders<Answer>.Update
                .Set(q => q.Content, content)
                .Push(q => q.Comments, new Comment { Content = summary, CreatedAt = DateTime.Now });

            await _answerCollection.UpdateOneAsync(filter, update, cancellationToken: cancellationToken);

            return Ok();
        }

        [HttpPost]
        [Route("{id}/comment")]
        public async Task<ActionResult> CommentAsync([FromRoute] string id, [FromBody] CommentRequest request,
    CancellationToken cancellationToken)
        {
            var filter = Builders<Answer>.Filter.Eq(q => q.Id, id);
            var update = Builders<Answer>.Update.Push(q => q.Comments,
                new Comment { Content = request.Content, CreatedAt = DateTime.Now });

            await _answerCollection.UpdateOneAsync(filter, update, null, cancellationToken);

            return Ok();
        }

        [HttpPost]
        [Route("{id}/up")]
        public async Task<ActionResult> UpAsync([FromBody] string id, CancellationToken cancellationToken)
        {
            var vote = new Vote
            {
                Id = Guid.NewGuid().ToString(),
                SourceType = ConstVoteSourceType.Answer,
                SourceId = id,
                Direction = EnumVoteDirection.Up
            };

            await _voteCollection.InsertOneAsync(vote, cancellationToken);

            var filter = Builders<Answer>.Filter.Eq(q => q.Id, id);
            var update = Builders<Answer>.Update.Inc(q => q.VoteCount, 1).AddToSet(q => q.VoteUps, vote.Id);
            await _answerCollection.UpdateOneAsync(filter, update);

            return Ok();
        }

        [HttpPost]
        [Route("{id}/down")]
        public async Task<ActionResult> DownAsync([FromBody] string id, CancellationToken cancellationToken)
        {
            var vote = new Vote
            {
                Id = Guid.NewGuid().ToString(),
                SourceType = ConstVoteSourceType.Answer,
                SourceId = id,
                Direction = EnumVoteDirection.Down
            };

            await _voteCollection.InsertOneAsync(vote, cancellationToken);

            var filter = Builders<Answer>.Filter.Eq(q => q.Id, id);
            var update = Builders<Answer>.Update.Inc(q => q.VoteCount, -1).AddToSet(q => q.VoteDowns, vote.Id);
            await _answerCollection.UpdateOneAsync(filter, update);

            return Ok();
        }
    }
}

GitHub源码链接：

https://github.com/MINGSON666/Personal-Learning-Library/tree/main/ArchitectTrainingCamp/LighterApi

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