How to have dates only instead of datetimes in hl7 output ?

[adellieux]

Hi,

in PID segments, as well as in some others, we have a demand to remove time part of datetime
example : 20160823222400 -> "should be" 20160823

how can i achieve this when adding the datetime value to the DateTimeOfBirth property ?
is there a way to apply a format like "yyyyMMdd" ?

[aarondglover]

I assume you're meaning the output from .ToDelimitedString()

Unfortunately as it stands, you cannot. You'll have to do some post processing of the output to truncate it down the 8 characters..... alternatively, fork the project and change the appropriate line;

clear-hl7-net/src/ClearHl7/V230/Segments/PidSegment.cs

Line 270 in 3505817

DateTimeOfBirth.HasValue ? DateTimeOfBirth.Value.ToString(Consts.DateTimeFormatPrecisionSecond, culture) : null,

DateTimeOfBirth.HasValue ? DateTimeOfBirth.Value.ToString(Consts.DateTimeFormatPrecisionSecond, culture) : null,
        to
DateTimeOfBirth.HasValue ? DateTimeOfBirth.Value.ToString(Consts.DateFormatPrecisionDay, culture) : null,

[davebronson]

The HL7 spec calls out that PID.7 (Date/Time Of Birth) is date and time, but can be truncated to day precision if desired. For this reason we should keep the current default formatting as is and look at your second suggestion of implementing a precision registration, below.

[adellieux]

Thanks both for your time and suggestions.
I will first try to see why i should apply a change that is not HL7 compliant just for a, not yet released, third party web api, that seems to require a little change to be compliant.
Unfortunately, i am not allowed to consume time to contribute on projects other than those produced by the company i work for :-(

[aarondglover]

Yeah there is always a balance to be struck between "what the standard says" and real world implementations... Hl7 is one of the most loosly implemented standards between systems and I agree, our default should be standard compliant, but we want to inject these extensibility points so default behaviours can be overridden where appropriate

[aarondglover]

Unfortunately, i am not allowed to consume time to contribute on projects other than those produced by the company i work for :-(

You know this is a crazy stance... You're using a library which you might otherwise have to write from scratch.... So how much time do open source projects save your company??? 🤔

So you can spend time on a work around, or contribute a solution which I basically gave you an almost complete implementation of? I know which one I'd choose if I was your employer

[adellieux]

yes i totally agree with you
we are in a hurry, because of a national "standardization" ("Segur" in France)
if our software is not conform or comply to "Segur", our company is not allowed to sell its related software anymore

[aarondglover]

Ideally we could do something like this. Please feel free to implement this and submit back to the project :)

Type-Safe DateTime Precision Configuration for HL7 Serialization

Global Config Class

using System;
using System.Collections.Generic;
using System.Linq.Expressions;

public static class Hl7DateTimeFormatConfig
{
    public static string DefaultDateTimeFormat { get; set; } = Consts.DateTimeFormatPrecisionSecond;

    // Use (segmentType, propertyName) as the key for per-field precision
    private static readonly Dictionary<(Type, string), string> FieldPrecisions = new();

    // Type-safe registration method
    public static void SetPrecision<TSegment>(
        Expression<Func<TSegment, object?>> property,
        string format)
    {
        if (property.Body is MemberExpression member)
        {
            FieldPrecisions[(typeof(TSegment), member.Member.Name)] = format;
        }
        else if (property.Body is UnaryExpression unary && unary.Operand is MemberExpression unaryMember)
        {
            FieldPrecisions[(typeof(TSegment), unaryMember.Member.Name)] = format;
        }
        else
        {
            throw new ArgumentException("Expression is not a property", nameof(property));
        }
    }

    public static string GetFormatForField(Type segmentType, string propertyName)
    {
        if (FieldPrecisions.TryGetValue((segmentType, propertyName), out var format))
            return format;
        return DefaultDateTimeFormat;
    }
}

Registering Per-Field Precision (Type Safe)

// Set global default (affects all DateTimes)
Hl7DateTimeFormatConfig.DefaultDateTimeFormat = Consts.DateTimeFormatPrecisionSecond;

// Set specific field (PID.DateTimeOfBirth) to day precision
Hl7DateTimeFormatConfig.SetPrecision<PID>(x => x.DateTimeOfBirth, Consts.DateFormatPrecisionDay);

Using the Config in Serialization

DateTimeOfBirth.HasValue
    ? DateTimeOfBirth.Value.ToString(
        Hl7DateTimeFormatConfig.GetFormatForField(this.GetType(), nameof(DateTimeOfBirth)), culture)
    : null