C#•13mo ago

❔ How to rewrite this without second foreach?

static private IEnumerable<string> GetSubjectsCustomFields(
        IEnumerable<(string Id, string TypeId, CustomFieldsValueDto CustomFields)> subjects,
        IReadOnlySet<string> subjectIds,
        IEnumerable<ChannelSettingsDto> channelSettings)
    {
        var join = subjects
            .Where(subject => subjectIds.Contains(subject.Id))
            .Join(channelSettings,
                subject => subject.TypeId,
                setting => setting.SubjectType,
                (subject, setting) => (subject, setting));
        
        foreach (var tuple in join)
        {
            if (tuple.subject.CustomFields?.FieldValues != null
                 && tuple.subject.CustomFields.FieldValues
                     .TryGetValue( tuple.setting.CustomField, out var value))
            {
                yield return value.ToString();
            }
        }
    }

static private IEnumerable<string> GetSubjectsCustomFields(
        IEnumerable<(string Id, string TypeId, CustomFieldsValueDto CustomFields)> subjects,
        IReadOnlySet<string> subjectIds,
        IEnumerable<ChannelSettingsDto> channelSettings)
    {
        var join = subjects
            .Where(subject => subjectIds.Contains(subject.Id))
            .Join(channelSettings,
                subject => subject.TypeId,
                setting => setting.SubjectType,
                (subject, setting) => (subject, setting));
        
        foreach (var tuple in join)
        {
            if (tuple.subject.CustomFields?.FieldValues != null
                 && tuple.subject.CustomFields.FieldValues
                     .TryGetValue( tuple.setting.CustomField, out var value))
            {
                yield return value.ToString();
            }
        }
    }

11 Replies

SWEETPONYOP•13mo ago

I'd like to have only one linq query

Angius•13mo ago

.Select()?

SWEETPONYOP•13mo ago

but I can't write if statement in select

Angius•13mo ago

Sure you can

SWEETPONYOP•13mo ago

var join = subjects
            .Where(subject => subjectIds.Contains(subject.Id))
            .Join(channelSettings,
                subject => subject.TypeId,
                setting => setting.SubjectType,
                (subject, setting) => (subject, setting))
            .Select(tuple =>
            {
                if (tuple.subject.CustomFields?.FieldValues != null
                     && tuple.subject.CustomFields.FieldValues
                         .TryGetValue(tuple.setting.CustomField, out var value))
                { 
                    return value.ToString();
                }
            } );

var join = subjects
            .Where(subject => subjectIds.Contains(subject.Id))
            .Join(channelSettings,
                subject => subject.TypeId,
                setting => setting.SubjectType,
                (subject, setting) => (subject, setting))
            .Select(tuple =>
            {
                if (tuple.subject.CustomFields?.FieldValues != null
                     && tuple.subject.CustomFields.FieldValues
                         .TryGetValue(tuple.setting.CustomField, out var value))
                { 
                    return value.ToString();
                }
            } );

this is a little bit bad because I should return smth from select

Angius•13mo ago

Yeah, you would need an else And then .Where() to filter out the empty values

SWEETPONYOP•13mo ago

but actually I don't want to return smth on else

Angius•13mo ago

.Aggregate() could also work I guess

SWEETPONYOP•13mo ago

Omnissiah•13mo ago

maybe you can filter something first with .Where() to simplify the if in a more linear way but even without it simply returning null as Z says would be good

Accord•13mo ago

Was this issue resolved? If so, run /close - otherwise I will mark this as stale and this post will be archived until there is new activity.

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❔ How to rewrite this without second foreach?