212 lines
7.6 KiB
Go
212 lines
7.6 KiB
Go
package db
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import (
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"context"
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"github.com/pkg/errors"
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"gorm.io/gorm"
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"gorm.io/gorm/clause"
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"github.com/tamakyi/TamaBox/internal/dbutil"
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)
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// MaxFollowUpCount 每条提问允许的最大追问次数（防滥用）。
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const MaxFollowUpCount = 3
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// 追问相关错误，供 handler 区分处理，避免把业务错误当 500。
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var (
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ErrFollowUpLimitReached = errors.New("follow up limit reached")
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ErrFollowUpNotFound = errors.New("follow up not found")
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ErrFollowUpAlreadyAnswered = errors.New("follow up already answered")
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)
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var FollowUps FollowUpsStore
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type FollowUpsStore interface {
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// CreateIfBelowLimit 原子创建追问：仅当该问题追问次数未达上限时创建；
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// 事务内锁定问题行串行化并发追问，消除 count-then-create 竞态。已达上限返回 (false, ErrFollowUpLimitReached)。
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CreateIfBelowLimit(ctx context.Context, opts CreateFollowUpOptions) (created bool, err error)
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GetByQuestionID(ctx context.Context, questionID uint) ([]*FollowUp, error)
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// GetLatestByQuestionID 返回某条提问最新的一条追问；无追问时返回 (nil, nil)。
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GetLatestByQuestionID(ctx context.Context, questionID uint) (*FollowUp, error)
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// GetByQuestionIDs 批量获取多个提问的追问，按 question_id 分组返回（导出场景合并 N+1 为 1 次 IN 查询）。
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GetByQuestionIDs(ctx context.Context, questionIDs []uint) (map[uint][]*FollowUp, error)
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CountByQuestionID(ctx context.Context, questionID uint) (int64, error)
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// AnswerByID 回答某条追问；questionID 防越权（必须属于该问题），仅允许回答尚未回答的（answer 为空）。
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// 已回答返回 ErrFollowUpAlreadyAnswered，不存在/不属于该问题返回 ErrFollowUpNotFound。
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AnswerByID(ctx context.Context, questionID uint, id uint, answer string) error
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// UpdateAnswerByID 修改某条追问的回答内容（带 question_id 条件防越权），允许覆盖已回答的（供主人修改回复）。
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// 不存在/不属于该问题返回 ErrFollowUpNotFound。
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UpdateAnswerByID(ctx context.Context, questionID uint, id uint, answer string) error
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// DeleteByQuestionID 删除某条提问时级联清理其全部追问（软删除，与提问保持一致）。
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DeleteByQuestionID(ctx context.Context, questionID uint) error
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}
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func NewFollowUpsStore(db *gorm.DB) FollowUpsStore {
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return &followUps{db}
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}
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type followUps struct {
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*gorm.DB
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}
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// FollowUp 表示对某条提问的一轮追问。
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type FollowUp struct {
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dbutil.Model
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QuestionID uint `gorm:"index:idx_follow_up_question" json:"question_id"`
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Content string `gorm:"type:text" json:"content"`
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Answer string `gorm:"type:text" json:"answer"`
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}
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type CreateFollowUpOptions struct {
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QuestionID uint
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Content string
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}
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func (db *followUps) CreateIfBelowLimit(ctx context.Context, opts CreateFollowUpOptions) (bool, error) {
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created := false
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err := db.WithContext(ctx).Transaction(func(tx *gorm.DB) error {
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// 锁定问题行，串行化同一问题的并发追问（MySQL/Postgres 均支持 FOR UPDATE）。
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var q Question
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if err := tx.Clauses(clause.Locking{Strength: "UPDATE"}).
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Select("id").
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First(&q, opts.QuestionID).Error; err != nil {
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return errors.Wrap(err, "lock question for follow up")
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}
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var count int64
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if err := tx.Model(&FollowUp{}).
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Where("question_id = ?", opts.QuestionID).
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Count(&count).Error; err != nil {
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return errors.Wrap(err, "count follow ups by question id")
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}
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if count >= MaxFollowUpCount {
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return ErrFollowUpLimitReached
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}
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f := &FollowUp{
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QuestionID: opts.QuestionID,
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Content: opts.Content,
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}
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if err := tx.Create(f).Error; err != nil {
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return errors.Wrap(err, "create follow up")
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}
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created = true
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return nil
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})
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if err != nil {
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return false, err
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}
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return created, nil
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}
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// GetByQuestionID 按时间正序返回某条提问的所有追问。
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func (db *followUps) GetByQuestionID(ctx context.Context, questionID uint) ([]*FollowUp, error) {
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var followUps []*FollowUp
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if err := db.WithContext(ctx).
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Where("question_id = ?", questionID).
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Order("created_at ASC").
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Find(&followUps).Error; err != nil {
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return nil, errors.Wrap(err, "get follow ups by question id")
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}
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return followUps, nil
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}
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// GetLatestByQuestionID 返回某条提问最新的一条追问（created_at 倒序）；无追问时返回 (nil, nil)，供发布前校验上一条是否已回复。
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func (db *followUps) GetLatestByQuestionID(ctx context.Context, questionID uint) (*FollowUp, error) {
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var fu FollowUp
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err := db.WithContext(ctx).
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Where("question_id = ?", questionID).
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Order("created_at DESC").
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Limit(1).
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First(&fu).Error
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if err != nil {
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if errors.Is(err, gorm.ErrRecordNotFound) {
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return nil, nil
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}
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return nil, errors.Wrap(err, "get latest follow up by question id")
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}
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return &fu, nil
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}
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// GetByQuestionIDs 批量获取多个提问的追问，按 question_id 分组返回（解决导出 N+1）。
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func (db *followUps) GetByQuestionIDs(ctx context.Context, questionIDs []uint) (map[uint][]*FollowUp, error) {
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result := make(map[uint][]*FollowUp)
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if len(questionIDs) == 0 {
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return result, nil
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}
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var items []*FollowUp
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if err := db.WithContext(ctx).
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Where("question_id IN ?", questionIDs).
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Order("question_id ASC, created_at ASC").
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Find(&items).Error; err != nil {
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return nil, errors.Wrap(err, "get follow ups by question ids")
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}
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for _, fu := range items {
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result[fu.QuestionID] = append(result[fu.QuestionID], fu)
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}
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return result, nil
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}
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// CountByQuestionID 统计某条提问的追问次数，用于限制追问上限。
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func (db *followUps) CountByQuestionID(ctx context.Context, questionID uint) (int64, error) {
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var count int64
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if err := db.WithContext(ctx).
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Model(&FollowUp{}).
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Where("question_id = ?", questionID).
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Count(&count).Error; err != nil {
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return 0, errors.Wrap(err, "count follow ups by question id")
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}
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return count, nil
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}
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// AnswerByID 更新回答（带 question_id 防越权）。
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// 原子条件含 answer=”，已回答的不被覆盖；RowsAffected==0 再查一次以区分"不存在"与"已回答"。
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func (db *followUps) AnswerByID(ctx context.Context, questionID uint, id uint, answer string) error {
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res := db.WithContext(ctx).
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Model(&FollowUp{}).
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Where("id = ? AND question_id = ? AND answer = ''", id, questionID).
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Update("answer", answer)
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if res.Error != nil {
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return errors.Wrap(res.Error, "answer follow up")
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}
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if res.RowsAffected == 0 {
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var cnt int64
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if err := db.WithContext(ctx).
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Model(&FollowUp{}).
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Where("id = ? AND question_id = ?", id, questionID).
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Count(&cnt).Error; err != nil {
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return errors.Wrap(err, "check follow up existence")
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}
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if cnt == 0 {
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return ErrFollowUpNotFound
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}
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return ErrFollowUpAlreadyAnswered
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}
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return nil
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}
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// UpdateAnswerByID 修改某条追问的回答内容（带 question_id 条件防止越权），
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// 允许覆盖已回答的追问（用于主人修改回复）。不存在/不属于该问题返回 ErrFollowUpNotFound。
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func (db *followUps) UpdateAnswerByID(ctx context.Context, questionID uint, id uint, answer string) error {
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res := db.WithContext(ctx).
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Model(&FollowUp{}).
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Where("id = ? AND question_id = ?", id, questionID).
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Update("answer", answer)
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if res.Error != nil {
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return errors.Wrap(res.Error, "update follow up answer")
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}
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if res.RowsAffected == 0 {
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return ErrFollowUpNotFound
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}
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return nil
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}
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// DeleteByQuestionID 删除某条提问时级联清理其全部追问（软删除，与提问保持一致）。
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func (db *followUps) DeleteByQuestionID(ctx context.Context, questionID uint) error {
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if err := db.WithContext(ctx).Where("question_id = ?", questionID).Delete(&FollowUp{}).Error; err != nil {
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return errors.Wrap(err, "delete follow ups by question id")
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}
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return nil
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}
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