创建通用方法 [英] Creating generic method

问题描述

有人可以提供以下帮助吗?这让我发疯了……

Can someone please help with the following... it's driving me nuts...

// Three methods, virtually identical with the exception of the select field
public IEnumerable<int> GetBrandID()
{
    return myData.Select(m => m.BrandID).Distinct();
}
public IEnumerable<int> GetModelID()
{
    return myData.Select(m => m.ModelID).Distinct();
}
public IEnumerable<int> GetVehicleID()
{
    return myData.Select(m => m.VehicleID).Distinct();
}

// How to create one method which returns the type specified in the parameter??
public IEnumerable<int> GetData(??? myType)
{
    return myData.Select(m => myType).Distinct();
}

推荐答案

听起来您可能只想要一个Func<Model, int>参数:

It sounds like you probably just want a Func<Model, int> parameter:

public IEnumerable<int> GetData(Func<Model, int> projection)
{
    return myData.Select(projection).Distinct();
}

您可以这样:

var modelIds = GetData(m => m.ModelID);
var vehicleIds = GetData(m => m.VehicleID);

这就是你的追求吗? (假设myData是IEnumerable<Model>.如果它是IQueryable<Model>，则可能要接受Expression<Func<Model, int>>.)

Is that what you're after? (That's assuming myData is an IEnumerable<Model>. If it's an IQueryable<Model> you may want to accept Expression<Func<Model, int>> instead.)

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