LinkarClientSelectAsync Method

Linkar Framework for .NET and Core

Executes a Query in the Database, in a asynchronous way with JSON output format.

Namespace: Linkar.Functions.Persistent.JSON
Assembly: Linkar.Functions.Persistent.JSON (in Linkar.Functions.Persistent.JSON.dll) Version: 2.3.1

Syntax

C++

Copy

public Task<string> SelectAsync(
	string filename,
	string selectClause = "",
	string sortClause = "",
	string dictClause = "",
	string preSelectClause = "",
	SelectOptions selectOptions = null,
	JSON_FORMAT jsonFormat = JSON_FORMAT.JSON,
	string customVars = "",
	int receiveTimeout = 0
)

Public Function SelectAsync ( 
	filename As String,
	Optional selectClause As String = "",
	Optional sortClause As String = "",
	Optional dictClause As String = "",
	Optional preSelectClause As String = "",
	Optional selectOptions As SelectOptions = Nothing,
	Optional jsonFormat As JSON_FORMAT = JSON_FORMAT.JSON,
	Optional customVars As String = "",
	Optional receiveTimeout As Integer = 0
) As Task(Of String)

public:
Task<String^>^ SelectAsync(
	String^ filename, 
	String^ selectClause = L"", 
	String^ sortClause = L"", 
	String^ dictClause = L"", 
	String^ preSelectClause = L"", 
	SelectOptions^ selectOptions = nullptr, 
	JSON_FORMAT jsonFormat = JSON_FORMAT::JSON, 
	String^ customVars = L"", 
	int receiveTimeout = 0
)

member SelectAsync : 
        filename : string * 
        ?selectClause : string * 
        ?sortClause : string * 
        ?dictClause : string * 
        ?preSelectClause : string * 
        ?selectOptions : SelectOptions * 
        ?jsonFormat : JSON_FORMAT * 
        ?customVars : string * 
        ?receiveTimeout : int 
(* Defaults:
        let _selectClause = defaultArg selectClause ""
        let _sortClause = defaultArg sortClause ""
        let _dictClause = defaultArg dictClause ""
        let _preSelectClause = defaultArg preSelectClause ""
        let _selectOptions = defaultArg selectOptions null
        let _jsonFormat = defaultArg jsonFormat JSON_FORMAT.JSON
        let _customVars = defaultArg customVars ""
        let _receiveTimeout = defaultArg receiveTimeout 0
*)
-> Task<string>

Parameters

filename String: Name of file on which the operation is performed. For example LK.ORDERS
selectClause String (Optional): Statement fragment specifies the selection condition. For example WITH CUSTOMER = '1'
sortClause String (Optional): Statement fragment specifies the selection order. If there is a selection rule, Linkar will execute a SSELECT, otherwise Linkar will execute a SELECT. For example BY CUSTOMER
dictClause String (Optional): Space-delimited list of dictionaries to read. If this list is not set, all fields are returned. For example CUSTOMER DATE ITEM. You may use the format LKFLDx where x is the attribute number.
preSelectClause String (Optional): An optional command that executes before the main Select
selectOptions SelectOptions (Optional): Object with options to manage how records are selected, including calculated, dictionaries, conversion, formatSpec, originalRecords, onlyItemId, pagination, regPage, numPage.
jsonFormat JSON_FORMAT (Optional): Enum JSON_FORMAT specifies the desired output format: standard JSON, JSON_DICT format, or JSON_SCH format
customVars String (Optional): Free text sent to the database allows management of additional behaviours in SUB.LK.MAIN.CONTROL.CUSTOM, which is called when this parameter is set.
receiveTimeout Int32 (Optional): Maximum time in seconds that the client will wait for a response from the server. Default = 0 to wait indefinitely.

Return Value

TaskString
The results of the operation.

Remarks

In the preSelectClause argument these operations can be carried out before executing the Select statement:

Previously call to a saved list with the GET.LIST command to use it in the Main Select input
Make a previous Select to use the result as the Main Select input, with the SELECT or SSELECT commands.In this case the entire sentence must be indicated in the PreselectClause. For example:SSELECT LK.ORDERS WITH CUSTOMER = '1'
Exploit a Main File index to use the result as a Main Select input, with the SELECTINDEX command. The syntax for all the databases is SELECTINDEX index.name.value. For example SELECTINDEX ITEM,"101691"

Example

C++

Copy

using Linkar;
using Linkar.Functions.Persistent.JSON;

class Test
    {
        public string MySelect()
        {
            string result = "";
            try
            {
                CredentialOptions credentials = new CredentialOptions("127.0.0.1", "EPNAME", 11300, "admin", "admin");
                LinkarClient client = new LinkarClient();
                client.Login(credentials);

                result = client.SelectAsync("LK.CUSTOMERS").Result;
                client.Logout();
            }
            catch (Exception ex)
            {
                string error = ex.Message;
                // Do something
            }
            return result;
        }
    }

Imports Linkar
Imports Linkar.Functions.Persistent.JSON

Class Test

    Public Function MySelect() As String
        Dim result As String = ""

        Try
            Dim credentials As CredentialOptions = New CredentialOptions("127.0.0.1", "EPNAME", 11300, "admin", "admin")

            Dim client As LinkarClient = New LinkarClient()

            client.Login(credentials)

            result = client.SelectAsync("LK.CUSTOMERS").Result
            client.Logout()
        Catch ex As Exception
            Dim[error] As String = ex.Message
            ' Do something

        End Try

        Return result
  End Function
End Class

Reference

LinkarClient Class

Linkar.Functions.Persistent.JSON Namespace