如何使PXDBTimeSpanLongAttribute支持负时长的输入与显示？

Absolutely! I’ve worked through this exact requirement in Acumatica before, and building a custom attribute that extends PXDBTimeSpanLongAttribute is the perfect solution. Below is a complete implementation that supports negative duration values for both display (converting stored total minutes to a readable format like -HH:mm) and user input (parsing negative time strings back to total minutes):

using PX.Data;
using System;

public class PXDBTimeSpanLongWithNegativeAttribute : PXDBTimeSpanLongAttribute
{
    public PXDBTimeSpanLongWithNegativeAttribute() : base()
    {
        // Retain base attribute behavior while overriding formatting/parsing logic
    }

    public override void FieldSelecting(PXCache cache, PXFieldSelectingEventArgs e)
    {
        base.FieldSelecting(cache, e);
        
        if (e.ReturnValue is int totalMinutes)
        {
            // Handle negative values by calculating absolute minutes first
            bool isNegative = totalMinutes < 0;
            int absMinutes = Math.Abs(totalMinutes);
            int hours = absMinutes / 60;
            int minutes = absMinutes % 60;
            
            // Format with negative sign if needed, ensuring 2-digit hours/minutes
            e.ReturnValue = $"{(isNegative ? "-" : "")}{hours:D2}:{minutes:D2}";
        }
    }

    public override void FieldUpdating(PXCache cache, PXFieldUpdatingEventArgs e)
    {
        if (e.NewValue is string inputString && !string.IsNullOrEmpty(inputString))
        {
            bool isNegative = inputString.StartsWith("-");
            string cleanInput = isNegative ? inputString.TrimStart('-') : inputString;
            
            // Parse the time string in HH:mm format
            if (TimeSpan.TryParse(cleanInput, out TimeSpan parsedTime))
            {
                int totalMinutes = (int)parsedTime.TotalMinutes;
                // Apply negative sign if the input included one
                e.NewValue = isNegative ? -totalMinutes : totalMinutes;
            }
            else
            {
                // Custom error handling for invalid input
                throw new PXSetPropertyException("Invalid time format. Use HH:mm with optional negative sign (e.g., -01:30).");
            }
        }
        
        base.FieldUpdating(cache, e);
    }
}

Key Details About This Implementation: #

• Display Logic: Overrides FieldSelecting to convert stored integer minutes (positive or negative) into a user-friendly HH:mm format, adding a negative sign when the total minutes are negative.
• Input Parsing: Overrides FieldUpdating to recognize negative signs in user input, parse the time string, convert back to total minutes, and apply the negative value before storing.
• Error Handling: Includes basic validation for invalid input formats, which you can adjust to match your application's specific error handling standards.

How to Use This Attribute: #

Apply it to your DAC field that stores total minutes as a PXDBInt type, just like you would use the standard PXDBTimeSpanLongAttribute:

public class YourDAC : IBqlTable
{
    // ... other DAC fields ...

    [PXDBInt]
    [PXUIField(DisplayName = "Duration (Minutes)")]
    [PXDBTimeSpanLongWithNegativeAttribute] // Use our custom attribute
    public virtual int? DurationMinutes { get; set; }
    public abstract class durationMinutes : PX.Data.BQL.BqlInt.Field<durationMinutes> { }
}

This setup will let users see negative durations formatted correctly (e.g., -02:15 for -135 minutes) and input negative times directly (like -01:45 which gets stored as -105 minutes).

内容的提问来源于stack exchange，提问作者Brendan