如何概括這些 linq 查詢

Question

我有這個方法：

 public IEnumerable<PackModel> PackLookup(short? society, string description)
        {
            return this.context.Pack.Where(x => x.Description.Contains(description) &&
                                                                        (!society.HasValue || x.Society == society))
                                                                       .OrderBy(x => x.Code)
                                                                       .Take(this.max);
        }

        public IEnumerable<FeaturesModel> FeaturesLookup(short? society, string description)
        {
            return this.context.Features.Where(x => x.Description.Contains(description) &&
                                                                    (!society.HasValue || x.Society == society))
                                                            .OrderBy(x => x.Code)
                                                            .Take(this.max);
        }

        public IEnumerable<ConstraintsModel> ConstraintsLookup(short? society, string description)
        {
            return this.context.Constraints.Where(x => x.Description.Contains(description) &&
                                                                    (!society.HasValue || x.Society == society))
                                                            .OrderBy(x => x.Code)
                                                            .Take(this.max);
        }

這三個方法非常相似，只是 DbSet 發生了變化，我怎樣才能以通用的方式進行這些調用以避免代碼重復

Answer 1

假設您的所有實體模型共享具有Description 、 Code和Society屬性的相同接口，那么您可以使用 DbContext 的Set<T>方法和泛型類型約束進行抽象，例如：

public IEnumerable<TModel> Lookup<TModel>(short? society, string description)
    where TModel : class, IYourInterface
{
    return this.context.Set<TModel>()
        .Where(x => x.Description.Contains(description) &&
                    (!society.HasValue || x.Society == society))
        .OrderBy(x => x.Code)
        .Take(this.max);
}

現在你這樣稱呼它：

var results = Lookup<PackModel>("society", "description");
var results = Lookup<FeaturesModel>("society", "description");
var results = Lookup<ConstraintsModel>("society", "description");