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Adding Parameters

Description

In this example, we add a Parameter to the Service Endpoint Page.

Discussion

Our first attempt at an endpoint is just to Demonstrate that an A5W page does not need to return just HTML. Lets say we wanted to be able to Return the Contents of either the Customers or the Products table.

To do this, Edit the endpoint page to take a 'tablename' parameter, which will select the table to use, or return an error.

Add the code below to the top of the page, replacing the dim sql as c variable assignment.

dim tablename as c
' Validate the tablename
if eval_valid("request.variables.tablename") then
	tablename = request.variables.tablename
    if tablename <> "Customers" .and. tablename <> "Products" then
        ? "{ \"error\" : \"Cannot Access table "+tablename+"\" }"
    	end 
    end if
else
    ? "{ \"error\" : \"No tablename specified \" }"
  	end 
end if

dim sql as c = "select * from "+tablename

Page With Parameters Changes Applied

<%a5
dim tablename as c
' Validate the tablename
if eval_valid("request.variables.tablename") then
	tablename = request.variables.tablename
    if tablename <> "Customers" .and. tablename <> "Products" then
        ? "{ \"error\" : \"Cannot Access table "+tablename+"\" }"
    	end 
    end if
else
    ? "{ \"error\" : \"No tablename specified \" }"
  	end 
end if

dim sql as c = "select * from "+tablename

dim cn as sql::Connection
cn.PortableSQLEnabled = .t.
if cn.Open("::Name::Northwind") then
	 if cn.Execute(sql) then
        dim rs as sql::ResultSet = cn.ResultSet
        dim responseJson as c = rs.ToJSONObjectSyntax()
        responseJson =  "{ \"items\" : [" + strtran( alltrim(responseJson) , crlf(), ","+crlf() ) + "] }"
	    ? json_reformat( responseJson )
     else
        dim resp.error as c = cn.CallResult.Text
        ? json_generate(resp)
	 end if
else
    dim resp.error as c = cn.CallResult.Text
    ? json_generate(resp)
end if
%>

Testing Service Endpoint With Parameters

Now if we use the original curl command, we receive a JSON packet with the error indicating that we have not specified a require paremeter.

Supply the parameter, and now our page can bring back either .

>curl "http://127.0.0.1:8081/service_endpoint.a5w"
{ "error" : "No tablename specified " }

>curl "http://127.0.0.1:8081/service_endpoint.a5w?tablename=products"
{
   "items": [
        {
            "ProductID": "1",
            "ProductName": "Chai",
            "SupplierID": "1",
            "CategoryID": "1",
            "QuantityPerUnit": "10 boxes x 20 bags",
            "UnitPrice": "18",
            "UnitsInStock": "39",
            "UnitsOnOrder": "0",
            "ReorderLevel": "10",
            "Discontinued": "F"
        },
        {
            "ProductID": "2",
        .....