过滤和 ICollectionView 过滤器 WPF

Question

我目前有一个DataGrid，其中包含我根据两件事过滤的公司 - 一个是用户可以根据公司名称、城镇或邮政编码过滤的搜索框。看起来像这样；

按名称/城镇/邮政编码过滤

        private void FilterDataGrid()
        {
            try
            {
                var searchText = CharactersOnly(searchBox.Text);
                CompanyICollectionView.Filter = (obj =>
                {
                    CompanyModel compDetails = obj as CompanyModel;
                    if (compDetails == null)
                    {
                        return true;
                    }

                    if (compNameRad.IsChecked == true)
                    {
                        return CompanyContains(compDetails.Name, searchText.ToLower());
                    }
                    if (compTownRad.IsChecked == true)
                    {
                        return CompanyContains(compDetails.Town, searchText.ToLower());
                    }
                    if (compPcodeRad.IsChecked == true)
                    {
                        return CompanyContains(compDetails.Postcode, searchText.ToLower());
                    }
                    return false;
                });

                if (dataGrid.Items.Count == 0) // There are no companies with this filter on, clear the label
                {
                    compDetailsLabel.Content = string.Empty;
                }
                else
                {
                    dataGrid.SelectedIndex = 0;
                }
            }
            catch (Exception ex)
            {
                var hEs = new HandleExceptionService();
                hEs.HandleException(ex.ToString());
            }
        }

第二种过滤方法是基于公司的类型。这是通过选择多个CheckBoxes 来完成的。这个方法看起来是这样的；

按公司类型过滤

    private void FilterCompanyType(object sender, RoutedEventArgs e)
    {
        criteria.Clear();

        if (currentCheckBox.IsChecked == true && nonCurrentCheckBox.IsChecked == false)
        {
            criteria.Add(new Predicate<CompanyModel>(x => x.CurrentStatus == 1));
        }
        else if (nonCurrentCheckBox.IsChecked == true && currentCheckBox.IsChecked == false)
        {
            criteria.Add(new Predicate<CompanyModel>(x => x.CurrentStatus == 0));
        }
        else if (nonCurrentCheckBox.IsChecked == true && currentCheckBox.IsChecked == true)
        {
            criteria.Add(new Predicate<CompanyModel>(x => (x.CurrentStatus == 1 || x.CurrentStatus == 0)));
        }

        if (subbieCheckBox.IsChecked == true)
        {
            criteria.Add(new Predicate<CompanyModel>(x => x.Subcontractor == 1));
        }

        if (supplierCheckBox.IsChecked == true)
        {
            criteria.Add(new Predicate<CompanyModel>(x => x.Supplier == 1));
        }

        if (planthireCheckBox.IsChecked == true)
        {
            criteria.Add(new Predicate<CompanyModel>(x => x.Planthire == 1));
        }

        if (architectCheckBox.IsChecked == true)
        {
            criteria.Add(new Predicate<CompanyModel>(x => x.Architect == 1));
        }

        if (qsCheckBox.IsChecked == true)
        {
            criteria.Add(new Predicate<CompanyModel>(x => x.QS == 1));
        }

        if (projectManagerCheckBox.IsChecked == true)
        {
            criteria.Add(new Predicate<CompanyModel>(x => x.ProjectManager == 1));
        }

        if (structEngCheckBox.IsChecked == true)
        {
            criteria.Add(new Predicate<CompanyModel>(x => x.StructEng == 1));
        }

        if (servEngCheckBox.IsChecked == true)
        {
            criteria.Add(new Predicate<CompanyModel>(x => x.ServiceEng == 1));
        }

        foreach (CheckBox checkBox in companyFilters.Children)
        {
            if (!CheckCheckBoxes())
            {
                dataGrid.ItemsSource = null;
                compDetailsLabel.Content = string.Empty;
            }
            else
            {
                dataGrid.ItemsSource = CompanyICollectionView;
                CompanyICollectionView.Filter = dynamic_Filter;
                SetSelectedCompany(selectedIndex);
                dataGrid.SelectedIndex = 0;
            }
        }

        var nfi = (NumberFormatInfo)CultureInfo.InvariantCulture.NumberFormat.Clone();
        nfi.NumberGroupSeparator = ",";
        numberOfCompaniesLabel.Content = "Number of Companies: " + dataGrid.Items.Count.ToString("#,#", nfi);
    }

这两种过滤方法本身看起来都很好。当我想过滤已应用于 DataGrid 的过滤器时，问题就出现了。例如，用户想要筛选出公司类型，因此他们选择了currentCheckBox、supplierCheckBox 和subbieCheckBox。这将返回所有当前也是分包商的供应商。

这仍然会返回一个包含 5000 家公司的列表，因此用户想要使用搜索功能来查找他们知道名称的公司。但它不会搜索过滤后的CompanyICollection，它会重置它并过滤整个列表（27000 家公司）。

我认为问题在于，当我想搜索现有的 CompanyICollectionView.Fiilter 时，我每次都在创建一个新的 CompanyICollectionView.Fiilter。有没有办法过滤已经过滤的ICollectionView？

编辑（添加动态过滤器）：

        private bool dynamic_Filter(object item)
        {
            CompanyModel company = item as CompanyModel;
            bool isIn = true;
            if (criteria.Count() == 0)
                return isIn;
            isIn = criteria.TrueForAll(x => x(company));
            return isIn;
        }

Answer 1

无需在每次属性更改时重新创建过滤器。 最适合您的做法是将两个过滤器组合在一个函数中，将其传递给CompanyICollectionView.Filter，并从属性更改事件中调用CompanyICollectionView.Refresh();。 您甚至可以将您的 collectionview 绑定到支持过滤的 ObservableCollection，即 FilteredObservableCollection... 看一下： CollectionViewSource Filter not refreshed when Source is changed

Answer 2

你是对的，问题是你每次都在重置过滤器。所以你需要做一些修改来解决你的问题（我会假设所有的代码都在同一个类中）：

private bool filterCompanyInfos(object o){
    //Function which return true if selected info and filter (name, town, code,...) corresponds to the object o (casted as a CompanyModel)
    //I let you write this part, should be like the filterCompanyType method.
}

private bool filterCompanyType(object o){
    criteria.Clear();

    if (currentCheckBox.IsChecked == true && nonCurrentCheckBox.IsChecked == false)
    {
        criteria.Add(new Predicate<CompanyModel>(x => x.CurrentStatus == 1));
    }
    else if (nonCurrentCheckBox.IsChecked == true && currentCheckBox.IsChecked == false)
    {
        criteria.Add(new Predicate<CompanyModel>(x => x.CurrentStatus == 0));
    }
    else if (nonCurrentCheckBox.IsChecked == true && currentCheckBox.IsChecked == true)
    {
        criteria.Add(new Predicate<CompanyModel>(x => (x.CurrentStatus == 1 || x.CurrentStatus == 0)));
    }
    //.... All other criterias here

    CompanyModel company = o as CompanyModel;
    bool isIn = true;
    if (criteria.Count() == 0)
        return isIn;
    isIn = criteria.TrueForAll(x => x(company));
    return isIn;
}

private bool FilterCompany(object o){
    return filterCompanyType(o) && filterCompanyInfos(o)
}


public void ApplyFilter(CollectionView companyCollectionView){
    CompanyICollectionView.Filter = this.FilterCompany;
    //do some other stuff like selected index ...
}