将lambda函数作为参数传递，并在方法主体中提供其参数

Posted 2021-05-06

[我有一种方法可以处理插件的一些分页逻辑；

public async Task<JsonResult> DataPagination()
{
    List<GLAccountModel> glAccounts = await HttpClientHelper.GetListHttpResponseAsync<GLAccountModel>(httpBaseAdress, "GLAccount", "GetAll");

    var (filteredResultCount, totalRecord) = DataTableHelper.ManageDataTable(glAccounts, Request, x => x.Name.Contains());

    return Json(new { data = glAccounts, draw = Request["draw"], recordsTotal = totalRecord, recordsFiltered = filteredResultCount });
}

[这里，我将lambda函数x => x.Name.Contains()传递给ManageDataTable方法。这是ManageDataTable方法的实现；

public static (int, int) ManageDataTable<TModel>(List<TModel> models, HttpRequestBase request, Func<TModel, bool> lambdaExpression) where TModel : class
{               
    string search = request["search[value]"];//arama

    if (!string.IsNullOrEmpty(search))
    {
        models = models.Where(lambdaExpression).ToList();
    }

    return (filteredResultCount, totalRecord);
}

我希望能够在Contains()方法的主体中提供ManageDataTable()方法的参数，而不是随参数本身一起发送。更清楚地说，我想从x => x.Name.Contains()接收lambda函数ManageDataTable()，并且在ManageDataTable()主体内部，我希望能够给Contains()方法提供参数，这是我的lambda的一部分功能。那可能吗？谢谢。

答案

我可以在这里根据更改方法参数来想到两个选项。您可以像这样将其设置为Func<string, Func<TModel, bool>>：

public static (int, int) ManageDataTable<TModel>(
    List<TModel> models,
    HttpRequestBase request,
    Func<string, Func<TModel, bool>> filterProvider)
    where TModel : class
{
    string search = request["search[value]"];//arama

    if (!string.IsNullOrEmpty(search))
    {
        var filter = filterProvider(search);
        models = models.Where(filter).ToList();
    }

    return (filteredResultCount, totalRecord);
}

您会这样称呼：

DataTableHelper.ManageDataTable(glAccounts, Request,
    search => model => model.Name.Contains(search));

此方法实际上是高阶方法。或者，您可以像这样输入Func<TModel, string, bool>：

public static (int, int) ManageDataTable<TModel>(
    List<TModel> models,
    HttpRequestBase request,
    Func<TModel, string, bool> filter)
    where TModel : class
{
    string search = request["search[value]"];//arama

    if (!string.IsNullOrEmpty(search))
    {
        models = models.Where(model => filter(model, search)).ToList();
    }

    return (filteredResultCount, totalRecord);
}

您会这样称呼：

DataTableHelper.ManageDataTable(glAccounts, Request,
    (model, search) => model.Name.Contains(search));

使用哪一个无关紧要，但是值得您确保他们都理解。