如何用Golang筛选输出日期区间内指定星期几的日期

Let's adjust your code to only output the dates that match your target weekday (like Monday or Tuesday) within the start/end date range. The key is to calculate the first matching date in the range and then increment by 7 days each time (since weekdays repeat weekly) instead of iterating every single day.

Modified Code #

func GetSchedule(c *gin.Context) {
    response := ResponseControllerList{}
    selected_day := "Monday"
    conditions := bson.M{"day": selected_day}

    data, err := models.GetSchedulingListing(conditions)
    if err != nil {
        // Handle database retrieval error early
        response = ResponseControllerList{
            config.FailureCode,
            config.FailureFlag,
            config.FailureMsg,
            nil,
            nil,
        }
        GetResponseList(c, response)
        return
    }

    // Map weekday strings to Go's time.Weekday constants for easy comparison
    weekdayMap := map[string]time.Weekday{
        "Sunday":    time.Sunday,
        "Monday":    time.Monday,
        "Tuesday":   time.Tuesday,
        "Wednesday": time.Wednesday,
        "Thursday":  time.Thursday,
        "Friday":    time.Friday,
        "Saturday":  time.Saturday,
    }

    targetWeekday, ok := weekdayMap[selected_day]
    if !ok {
        // Handle invalid weekday input
        response = ResponseControllerList{
            config.FailureCode,
            config.FailureFlag,
            "Invalid weekday specified",
            nil,
            nil,
        }
        GetResponseList(c, response)
        return
    }

    for _, item := range data {
        start_date := item.StartDate
        end_date := item.EndDate
        start_time := item.StartTime
        end_time := item.EndTime

        start_working_hours := time.Unix(start_time, 0).Format("3:04PM")
        end_working_hours := time.Unix(end_time, 0).Format("3:04PM")

        // Convert Unix timestamps to time.Time objects for easier date manipulation
        currentDate := time.Unix(start_date, 0)
        endDate := time.Unix(end_date, 0)

        // Calculate days needed to jump to the first occurrence of the target weekday
        daysToAdd := (int(targetWeekday) - int(currentDate.Weekday()) + 7) % 7
        currentDate = currentDate.AddDate(0, 0, daysToAdd)

        // Iterate weekly, outputting each matching weekday until we exceed the end date
        for !currentDate.After(endDate) {
            fmt.Println(currentDate.Format("Monday, 01-02-2006") + " " + start_working_hours + " " + end_working_hours)
            currentDate = currentDate.AddDate(0, 0, 7)
        }
    }

    dataCount, err := models.GetRecordsCount(config.ScheduleCollection, conditions)
    if err != nil {
        response = ResponseControllerList{
            config.FailureCode,
            config.FailureFlag,
            config.FailureMsg,
            nil,
            nil,
        }
    } else {
        response = ResponseControllerList{
            config.SuccessFlag,
            config.SuccessFlag,
            config.SuccessMsg,
            data[0],
            dataCount,
        }
    }

    GetResponseList(c, response)
}

Key Changes Explained #

• Weekday Mapping: We created a weekdayMap to convert human-readable weekday strings (like "Monday") to Go's built-in time.Weekday enum, which simplifies date comparison logic.
• Jump to First Matching Date: Instead of checking every single day, we calculate the exact number of days needed to reach the first target weekday from the start date. The +7 and %7 ensures we handle cases where the start date falls after the target weekday (e.g., start is Tuesday, target is Monday—we add 6 days to reach the next Monday).
• Efficient Weekly Iteration: Once we have the first matching date, we increment by 7 days each cycle (since weekdays repeat weekly) until we pass the end date. This is way more efficient than looping through every day, especially for large date ranges.
• Robust Error Handling: Added early checks for database retrieval failures and invalid weekday inputs to make the code more reliable.

Example Output #

If selected_day is "Monday" and your date range starts on Tuesday, 05-01-2018, the output will skip to the first Monday in the range (05-07-2018) and then list every subsequent Monday until the end date matches your desired result.

内容的提问来源于stack exchange，提问作者user9684058