Example 2: Component table querying multiple CSV files

This is a variation on Example 1. Instead of querying a CSV file identified by a hard-coded filepath, a column is added to the component table. This allows the user, at query time, to identify the CSV file to be queried.

Example

Here is an input file called C:\Temp\schedtour.csv that demonstrates the data format expected by the example component:

146,AUSTRALIA,ISLAND SUNTANNER,21-3-2020 11:59:01,1-4-2020 11:59:01,2500

145,AUSTRALIA,ISLAND SUNTANNER,20-11-2019 11:59:01,1-12-2019 11:59:01,2500

144,BRAZIL,RAINFOREST RIDE,16-10-2021 11:59:01,29-10-2021 11:59:01,3000

143,BRAZIL,RAINFOREST RIDE,15-9-2021 11:59:01,28-9-2021 11:59:01,3000

142,BRAZIL,RAINFOREST RIDE,15-8-2021 11:59:01,28-8-2021 11:59:01,5500

1.	Choose Define, RDMI, dotNet Components from the USoft Definer menu. The DotNetComponents window opens.

2.	Provide a Name for your new component, in this case: CSV.

3.	In the Program Source field, provide the source code of the component:

using System;
using System.Text;
using System.IO;
class CSV
{
string csvFileName = null;
StreamReader reader = null;

public long QueryExe(string fileName, Nullable<Int32> id, string destination, string tourType, Nullable<DateTime> startDate, Nullable<DateTime> returnDate, Nullable<Int32> price)
{
     csvFileName = fileName;
     if(String.IsNullOrEmpty(csvFileName))
         throw new Exception("Filename is not set.");
     reader = new StreamReader(csvFileName);
     return 1;
}

public long QueryFetch(out string fileName, out Nullable<Int32> id, out string destination, out string tourType, out Nullable<DateTime> startDate, out Nullable<DateTime> returnDate, out Nullable<Int32> price)
{
     id = null;
     destination = null;
     tourType = null;
     startDate = null;
     returnDate = null;
     price = null;
     fileName = csvFileName;
     if(reader.EndOfStream){
          reader.Close();
          return 0;
     }

     try{
          var line = reader.ReadLine();
          var values = line.Split(',');
          int n = 0;
          if(values[0] != null && !Int32.TryParse(values[0], out n))
               throw new Exception("Cannot convert value " + values[0] + " to a number");

          id = n;
          destination = values[1];
          tourType = values[2];
          if(values[3] != null)
               startDate = Convert.ToDateTime(values[3]);

          if(values[4] != null)
               returnDate = Convert.ToDateTime(values[4]);

          if(values[5] != null && !Int32.TryParse(values[5], out n))
               throw new Exception("Cannot convert value " + values[5] + " to a number");

          price = n;
     }catch(Exception e){
             reader.Close();
             throw e;
     }

     return 1;
}
}

4.	Save work.

5.	Press the Check button. The RDMI interface is generated by USoft.

6.	On the State tab, set:

•Stateful Component = Y

•Participant in Transaction = N

•Support tablecomponent = Y

•Update = N

•Insert = N

•Delete = N

7.	Save work.