将 Query<T, ..> 扩展到超过 7 种类型

Question

我正在使用 Dapper 来获取结果列表。我有很多只包含 ID 和名称的“价值”表。

我有这个 SQL；

SELECT 
    MedicationScheduleItem.*,
    MedicationSchedule.*,
    Patient.*,
    Medication.*,
    MedicationBrand.*,
    MedicationScheduleItemRepeat.*,
    MedicationType.*,
    Measure.*

FROM MedicationScheduleItem
JOIN MedicationSchedule ON (MedicationSchedule.Id = MedicationScheduleItem.MedicationScheduleId)
JOIN Patient ON (Patient.Id = MedicationSchedule.PatientId)
JOIN Medication ON (Medication.Id = MedicationScheduleItem.MedicationId)
JOIN MedicationBrand ON (MedicationBrand.Id = Medication.MedicationBrandId)
JOIN MedicationType ON (MedicationType.Id = Medication.MedicationTypeId)
JOIN Measure ON (Measure.Id = Medication.MeasureId)
LEFT JOIN MedicationScheduleItemRepeat ON (MedicationScheduleItemRepeat.MedicationScheduleItemId = MedicationScheduleItem.Id)

我正在尝试将该 SQL 映射到这样的模型；

using Dapper;

//... 

private readonly IDbConnection _connection;

//... 

private IEnumerable<MedicationScheduleResultModel> QueryMedicationScheduleResultModels(string sql, object parameters = null)
{
    var results = new Dictionary<int, MedicationScheduleResultModel>();

    _connection.Query<MedicationScheduleItem, MedicationSchedule, Patient, Medication, MedicationBrand, MedicationScheduleItemRepeat, MedicationType, Measure, MedicationScheduleResultModel>(sql,
                (medicationScheduleItem, medicationSchedule, patient, medication, medicationBrand, medicationScheduleItemRepeat, medicationType, measure) =>
                {
                    MedicationScheduleResultModel viewModel;
                    if (!results.TryGetValue(medicationSchedule.Id, out viewModel))
                    {
                        results.Add(medicationSchedule.Id, new MedicationScheduleResultModel
                        {
                            Id = medicationSchedule.Id,
                            Patient = patient,
                            TimeCreated = medicationSchedule.TimeCreated,
                            StartDate = medicationSchedule.StartDate,
                            Schedules = new List<MedicationScheduleItemResultModel>()
                            {
                                BuildMedicationScheduleItemResultModel(medicationScheduleItem,
                                    medicationScheduleItemRepeat, medication, medicationBrand, medicationType, measure)
                            }
                        });
                    }
                    else
                    {
                        viewModel.Schedules.Add(BuildMedicationScheduleItemResultModel(medicationScheduleItem,
                            medicationScheduleItemRepeat, medication, medicationBrand));
                    }

                    return viewModel;
                }, parameters, splitOn: "Id, MedicationScheduleItemId");

    return results.Values;
}

private static MedicationScheduleItemResultModel BuildMedicationScheduleItemResultModel(MedicationScheduleItem medicationScheduleItem, MedicationScheduleItemRepeat medicationScheduleItemRepeat, Medication medication, MedicationBrand medicationBrand, MedicationType medicationType, Measure measure)
{
    return new MedicationScheduleItemResultModel()
    {
        Id = medicationScheduleItem.Id,
        ExecuteTime = medicationScheduleItem.ExecuteTime,
        RepeatTimeSpan = medicationScheduleItemRepeat != null
            ? (TimeSpan?)TimeSpan.FromTicks(medicationScheduleItemRepeat.RepeatTimeSpan)
            : null,
        Medication = new MedicationResultModel()
        {
            Id = medication.Id,
            Name = medication.Name,
            Brand = new MedicationBrand()
            {
                Id = medicationBrand.Id,
                Name = medicationBrand.Name
            },
            Measure = measure.Name,
            Type = medicationType.Name,
            Weight = medication.Weight
        }
    };
}

但是_connection.Query<T, ..> 失败了，因为有很多泛型类型。

有没有办法让它工作，还是我做错了？

Answer 1

您可以尝试直接映射到您感兴趣的最终类型，而不是将您的 SQL 结果映射到所有这些类型并仅在初始化另一种类型时使用它们。

所以不要这样：

_connection.Query<MedicationScheduleItem, MedicationSchedule, Patient, 
    Medication, MedicationBrand, MedicationScheduleItemRepeat, MedicationType,
    Measure, MedicationScheduleResultModel>(...

这可能足以构建您需要的对象图：

_connection.Query<MedicationScheduleResultModel, Patient, 
    MedicationScheduleItemResultModel, MedicationResultModel, MedicationBrand>(...

当然，这需要修改您的SELECT 以返回适当的字段。比如……

SELECT
    -- columns that directly map to MedicationScheduleResultModel properties
    MedicationSchedule.id,
    MedicationSchedule.time_created TimeCreated, 
    MedicationSchedule.start_date StartDate,

    -- columns that directly map to Patient properties
    -- (to be used as MedicationScheduleResultModel.Patient)
    Patient.id, 
    Patient.name,

    -- columns that directly map to MedicationScheduleItemResultModel properties
    MedicationScheduleItem.id,
    MedicationScheduleItem.execute_time ExecuteTime,
    MedicationScheduleItemRepeat.repeat_time RepeatTime,

    -- columns that directly map to MedicationResultModel properties
    Medication.id,
    Medication.name,
    Measure.name,
    MedicationType.name,
    Medication.weight,

    -- columns that directly map to MedicationBrand properties
    MedicationBrand.id, 
    MedicationBrand.name
...

希望你能明白。

您甚至可以进一步展平，例如，MedicationResultModel，以便它不包含复杂的MedicationBrand 属性，而是包含MedicationBrandId 和MedicationBrandName 属性。但这取决于这是否适合您的其余设计。