QueryableFilterUserControl.GetQueryable(IQueryable) Metode

Definisi

Ruang nama:

System.Web.DynamicData

Rakitan:

System.Web.DynamicData.dll

Mendapatkan objek yang diubah IQueryable dari objek sumber IQueryable .

public:
 abstract System::Linq::IQueryable ^ GetQueryable(System::Linq::IQueryable ^ source);

public abstract System.Linq.IQueryable GetQueryable(System.Linq.IQueryable source);

abstract member GetQueryable : System.Linq.IQueryable -> System.Linq.IQueryable

Public MustOverride Function GetQueryable (source As IQueryable) As IQueryable

Parameter

source

IQueryable

Objek sumber IQueryable .

Mengembalikan

IQueryable

Objek yang diubah IQueryable dari objek sumber IQueryable .

Contoh

Metode ini diimplementasikan untuk mengubah objek sumber IQueryable menjadi objek target IQueryable . IQueryable Contoh ekspresi yang mungkin ingin Anda terapkan termasuk urutan menurut, rentang, atau pencarian.

Contoh berikut menunjukkan cara menerapkan GetQueryable metode untuk filter Boolean yang berasal dari QueryableFilterUserControl.

public override IQueryable GetQueryable(IQueryable source) {
    if (String.IsNullOrEmpty(DropDownList1.SelectedValue)) {
        return source;
    }

    bool value = Convert.ToBoolean(DropDownList1.SelectedValue);

    ParameterExpression parameterExpression =
        Expression.Parameter(source.ElementType, "item");
    Expression body = BuildQueryBody(
        parameterExpression, value);

    LambdaExpression lambda = Expression.Lambda(body,
        parameterExpression);
    MethodCallExpression whereCall = Expression.Call(
        typeof(Queryable),
        "Where",
        new Type[] { source.ElementType },
        source.Expression, Expression.Quote(lambda));
    return source.Provider.CreateQuery(whereCall);
}

Public Overloads Overrides Function GetQueryable(ByVal source As IQueryable) As IQueryable
    If [String].IsNullOrEmpty(DropDownList1.SelectedValue) Then
        Return source
    End If

    Dim value As Boolean = Convert.ToBoolean(DropDownList1.SelectedValue)

    Dim parameterExpression As ParameterExpression = Expression.Parameter(source.ElementType, "item")
    Dim body As Expression = BuildQueryBody(parameterExpression, value)

    Dim lambda As LambdaExpression = Expression.Lambda(body, parameterExpression)
    Dim whereCall As MethodCallExpression = Expression.[Call](GetType(Queryable), "Where", _
         New Type() {source.ElementType}, source.Expression, Expression.Quote(lambda))
    Return source.Provider.CreateQuery(whereCall)
End Function

Keterangan

Anda harus menerapkan metode ini jika Anda mendapatkan kontrol dari QueryableFilterUserControl.