Question

我正在开发一个CRM类型的应用程序，我正在实现的一个功能是能够查看数据网格，然后使用单个文本框来过滤任何列中的值。我想出了一个非常难看的解决方案（请注意，此方法也使用Dynamic Linq对数据进行排序），但是我希望它更“通用”，可能使用反射，所以我可以调用WithFiltering扩展方法和提供扩展方法的过滤条件。这就是我到目前为止所做的：

public List<PersonModel> GetPeople(int owningOrganisationID, int skip, int records, out int totalCount, Ordering orderByDirection, string filter, string orderBy = "")
    {
        if (string.IsNullOrEmpty(orderBy))
            orderBy = "PersonID";

        if (!string.IsNullOrEmpty(filter))
        {
            filter = filter.ToLower();

            totalCount = Context.PeopleView.Where(p => p.OwningOrganisationID == owningOrganisationID &&
                p.City.ToLower().Contains(filter)
                || p.CountryName.ToLower().Contains(filter)
                || p.Forename.ToLower().Contains(filter)
                || p.PersonTypeName.ToLower().Contains(filter)
                || p.Postcode.ToLower().Contains(filter)
                || p.Surname.ToLower().Contains(filter)).Count();

            return Context.PeopleView.Where(p => p.OwningOrganisationID == owningOrganisationID &&
                p.City.ToLower().Contains(filter)
                || p.CountryName.ToLower().Contains(filter)
                || p.Forename.ToLower().Contains(filter)
                || p.PersonTypeName.ToLower().Contains(filter)
                || p.Postcode.ToLower().Contains(filter)
                || p.Surname.ToLower().Contains(filter))
                    .OrderBy(orderBy + " " + orderByDirection.ToString())
                    .Skip(skip)
                    .Take(records)
                    .ToList();
        }
        else
        {
            totalCount = Context.PeopleView.Where(p => p.OwningOrganisationID == owningOrganisationID).Count();

            return Context.PeopleView
                .Where(o => o.OwningOrganisationID == owningOrganisationID)
                .OrderBy(orderBy + " " + orderByDirection.ToString())
                .Skip(skip)
                .Take(records)
                .ToList();
        }
    }

这不仅看起来很糟糕，而且容易出错，我会在几个不同的实体上使用相同类型的代码（PersonModel，OrganizationModel，DocumentModel等......）

只是想知道是否有人对清洁代码有更好的想法？

Answer 1

使用更正确的问题解决方案更新

不使用反射，您可以使用以下模式：

使用IFilterable方法

FilterClause(string filter)

在您的实体（IFilterable，PersonModel等）上实施OrganizationModel课程。）
为将应用过滤的IFilterable个对象编写扩展名
查询数据时使用此扩展程序

因此，基本上对于要应用相同过滤的每个实体，您可以实现IFilterable并定义属性和这些属性将用于哪些过滤

以下是一些说明上述概念的代码。首先，定义IFilterable并在您的实体类（PersonModel，OrganizationModel等）上实现它。）

/// <summary> /// Specifies that the class can be filterable /// </summary> interface IFilterable { /// <summary> /// Specifies the way the filtering will occur /// </summary> /// <param name="filter"></param> /// <returns></returns> bool FilterClause(string filter); } //partial class definition for PersonModel public partial class PersonModel: IFilterable{ //entity properties (normaly these are generated by EF) public int Id { get; set; } public int OwningOrganisationID { get; set; } public string City { get; set; } public string CountryName { get; set; } public string Forename { get; set; } public string PersonTypeName { get; set; } public string Postcode { get; set; } public string Surname { get; set; } //Implementation of IFiltrable public bool FilterClause(string filter) { return City.ToLower().Contains(filter) || CountryName.ToLower().Contains(filter) || Forename.ToLower().Contains(filter) || PersonTypeName.ToLower().Contains(filter) || Postcode.ToLower().Contains(filter) || Surname.ToLower().Contains(filter); } } //partial class definition for OrganizationModel public partial class OrganizationModel: IFilterable{ //Implementation of IFiltrable public bool FilterClause(string filter) { //replace 'true' with code that will apply filtering for the OrganizationModel class return true; } }

现在在IQueryable对象上定义一个扩展，该扩展将对实现'IFilterable'的对象应用过滤

static class FilterableEntensions{ /// <summary> /// Filters a IFilterable enumeration /// </summary> /// <typeparam name="T"></typeparam> /// <param name="query"></param> /// <param name="filter"></param> /// <returns></returns> public static IQueryable<T> WithFiltering<T>(this IQueryable<T> query, string filter) where T: IFilterable { if (string.IsNullOrWhiteSpace(filter)) { //filter is empty, return original query return query; } else { //apply the filter return query.Where(x => x.FilterClause(filter)); } } }

通过上述定义，您的GetPeople方法可以重写（见下文）。它还首先查询id仅设置totalCount值，并且仅查询最终查询的分页ID

public List<PersonModel> GetPeople(int owningOrganisationID, int skip, int records, out int totalCount, Ordering orderByDirection, string filter, string orderBy = "") { List<PersonModel> result = new List<PersonModel>(); if (string.IsNullOrEmpty(orderBy)) { orderBy = "PersonID"; } if (!string.IsNullOrWhiteSpace(filter)) { filter = filter.ToLower(); } //use a first query to take only the ids of the data that match the filter. List<int> peopleViewIds = Context.PeopleView .Where(p => p.OwningOrganisationID == owningOrganisationID) .WithFiltering(filter) //use our extension here!!! .OrderBy(orderBy + " " + orderByDirection.ToString()) .Select(p => p.Id).ToList(); //set the 'out' parameter to the total count of the retrieved ids totalCount = peopleViewIds.Count; if (totalCount > 0) { //page the ids accordingly (the sorting of the ids was applied in the previous query) List<int> pagedPeopleViewIds = peopleViewIds.Skip(skip).Take(records).ToList(); //use the paged ids to make a second query, this time only with the required ids. //This should be really fast if you have PersonModel.Id is a PRIMARY KEY or you have an index attached on this column //Please note the reuse of the OrderBy, this will ensure the correct order on the paged result result = Context.PeopleView.Where(p => pagedPeopleViewIds.Contains(p.Id)) .OrderBy(orderBy + " " + orderByDirection.ToString()) .ToList(); } return result; }

EF 5过滤任何列 - 扩展方法？

1 个答案: