Session.GetObjectsFromQueryAsync(XPClassInfo, List<XPMemberInfo>, String, CancellationToken) Method

Asynchronously executes a SQL query and returns its result set as a collection of non-persistent objects.

Namespace: DevExpress.Xpo

Assembly: DevExpress.Xpo.v24.2.dll

Declaration

C#

public Task<ICollection> GetObjectsFromQueryAsync(
    XPClassInfo classInfo,
    List<XPMemberInfo> members,
    string sql,
    CancellationToken cancellationToken = default(CancellationToken)
)

VB.NET

Public Function GetObjectsFromQueryAsync(
    classInfo As XPClassInfo,
    members As List(Of XPMemberInfo),
    sql As String,
    cancellationToken As CancellationToken = Nothing
) As Task(Of ICollection)

Parameters

Name	Type	Description
classInfo	XPClassInfo	An XPClassInfo object which contains the metadata information on a non-persistent class corresponding to the query’s result set. The class must be decorated with NonPersistentAttribute.
members	List<XPMemberInfo>	Specifies object members mapped to columns in the result set. The order of list elements should correspond to the order of result set columns.
sql	String	Specifies an SQL statement.

Optional Parameters

Name	Type	Default	Description
cancellationToken	CancellationToken	null	A CancellationToken object that delivers a cancellation notice to the running operation.

Returns

Type	Description
Task<ICollection>	A Task<TResult> that returns a collection of non-persistent classInfo objects instantiated with data obtained via the specified SQL query.

Remarks

C#

string sql = "select (FirstName + ' ' + LastName) as Name, City, Country from Employees";
XPClassInfo classInfo = session.GetClassInfo<EmployeeModel>();
List<XPMemberInfo> members = new List<XPMemberInfo>() { 
    classInfo.GetMember(nameof(EmployeeModel.Name)),
    classInfo.GetMember(nameof(EmployeeModel.City)),
    classInfo.GetMember(nameof(EmployeeModel.Country))
};
ICollection queryResultData = await session.GetObjectsFromQueryAsync(classInfo, members, sql);

VB.NET

Dim sql As String = "select (FirstName + ' ' + LastName) as Name, City, Country from Employees"
Dim classInfo As XPClassInfo = session.GetClassInfo(Of EmployeeModel)()
Dim members As New List(Of XPMemberInfo)() From {classInfo.GetMember(nameof(EmployeeModel.Name)), classInfo.GetMember(nameof(EmployeeModel.City)), classInfo.GetMember(nameof(EmployeeModel.Country))}
Dim queryResultData As ICollection = Await session.GetObjectsFromQueryAsync(classInfo, members, sql)

This method does the following:

• Executes the specified SQL query and obtains the query result.
• Creates objects using the specified classInfo and populates their properties with the resulting set’s data The members parameter specifies the mapping between columns in the resulting set and object properties. Note that classInfo should represent a non-persistent class decorated with a NonPersistentAttribute.

Note

The GetObjectsFromQueryAsync method throws an exception if the members array includes any of the following classInfo members:

• A property that is not defined within the classInfo object.
• A struct type member.
• A reference to a class with a struct type member.
• A collection used in object relations.

To learn more about executing SQL statements in XPO, refer to Direct SQL Queries.

Note

The GetObjectsFromQueryAsync method sends statements directly, so the correct statement syntax and parameter names format depends on a particular database server.