我怎样才能铸造IQueryable<>；查询到IQueryable<；obj.getType()>；

本文关键字：gt IQueryable lt obj getType 查询 | 更新日期: 2023-09-27 18:27:03

如何分解此代码？我的过滤器返回几种类型的文档。困难的是，我对每个类型都有一些查询。。。我想要一个返回正确查询的通用方法

感谢

        if(this.comboBoxType.Text.Equals("Vente"))
        {
            IQueryable<Vente> queryV = ContexteDAO.ContexteDonnees.Vente
               .Include("Client")
               .Include("Paiement")
               .Include("Employe").OrderBy(v => v.venteID);
            if (this.tbxNomCli.Text != "")
                queryV = queryV.Where(v => v.Client.nom.Contains(this.tbxNomCli.Text));
            if (this.comboBoxEtat.Text != "Tous")
                queryV = queryV.Where(v => v.etat == this.comboBoxEtat.Text);
            if (this.checkBoxDate.Checked)
                queryV = queryV.Where(v => v.date.Equals(this.dateTimePicker.Value.Date));
            if (this.tbxTva.Text != "")
                queryV = queryV.Where(v => v.Client.numEntreprise.Contains(this.tbxTva.Text));
            if (this.checkBoxVendeur.Checked)
            {
                Employe employe = this.comboBoxVendeur.SelectedItem as Employe;
                queryV = queryV.Where(v => v.Employe.login.Equals(employe.login));
            }
            this.documentBindingSource.DataSource = queryV.ToList();
        }
        if (this.comboBoxType.Text.Equals("Commande"))
        {
            IQueryable<Commande> queryC = ContexteDAO.ContexteDonnees.Commande
               .Include("Client")
               .Include("Paiement")
               .Include("Employe").OrderBy(c => c.commandeID);
            if (this.tbxNomCli.Text != "")
                queryC = queryC.Where(v => v.Client.nom.Contains(this.tbxNomCli.Text));
            if (this.comboBoxEtat.Text != "Tous")
                queryC = queryC.Where(v => v.etat == this.comboBoxEtat.Text);
            if (this.checkBoxDate.Checked)
                queryC = queryC.Where(v => v.date.Equals(this.dateTimePicker.Value.Date));
            if (this.tbxTva.Text != "")
                queryC = queryC.Where(v => v.Client.numEntreprise.Contains(this.tbxTva.Text));
            if (this.checkBoxVendeur.Checked)
            {
                Employe employe = this.comboBoxVendeur.SelectedItem as Employe;
                queryC = queryC.Where(v => v.Employe.login.Equals(employe.login));
            }
            this.documentBindingSource.DataSource = queryC.ToList();
        }

我怎样才能铸造IQueryable<>；查询到IQueryable<；obj.getType()>；

您可以使用一种通用方法：

public IQueryable<T> GetData<T>( string identifier )
{
     switch( identifier )
     {
         case "Vente":
         {
             return ContexteDAO.ContexteDonnees.Vente
                                               .Include("Client")
                                               .Include("Paiement")
                                               .Include("Employe")
                                               .OrderBy(v => v.venteID);
             // do more stuff
             break;
         }
         // add more cases
         default:
         {
             return null;
         }
     }
}

通话内容如下：

IQueryable<Vente> result = GetData<Vente>( "Vente" );

它可以解决你的问题，但我不喜欢它，因为你需要指定类型，并且需要一个标识符，你想执行哪个选择。当您有类似GetData<Vente>( "OtherEntity" )的东西时，这可能会很快导致异常。

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