The CData ADO.NET Provider for FHIR implements two ADO.NET interfaces you can use to retrieve data from FHIR: FHIRDataAdapter and FHIRDataReader objects. Whereas FHIRDataAdapter objects retrieve a single result set of all the data that matches a query, FHIRDataReader objects fetch data in subset increments as needed.

Using the FHIRDataAdapter

Use the adapter's Fill method to retrieve data from the data source. An empty DataTable instance is passed as an argument to the Fill method. When the method returns, the DataTable instance is populated with the queried data. Note that the FHIRDataAdapter is slower than the FHIRDataReader because the Fill method needs to retrieve all data from the data source before returning.

The following example selects the Id and [address-city] columns of the Patient table:

C#

string connectionString = "URL=http://test.fhir.org/r4b/;ConnectionType=Generic;ContentType=JSON;AuthScheme=None;";

using (FHIRConnection connection = new FHIRConnection(connectionString)) {
  FHIRDataAdapter dataAdapter = new FHIRDataAdapter(
  "SELECT Id, [address-city] FROM Patient", connection);

  DataTable table = new DataTable();
  dataAdapter.Fill(table);

  Console.WriteLine("Contents of Patient.");

  foreach (DataRow row in table.Rows) {
    Console.WriteLine("{0}: {1}", row["Id"], row["[address-city]"]);
  }
}

VB.NET

Dim connectionString As String = "URL=http://test.fhir.org/r4b/;ConnectionType=Generic;ContentType=JSON;AuthScheme=None;"

Using connection As New FHIRConnection(connectionString)
  Dim dataAdapter As New FHIRDataAdapter("SELECT Id, [address-city] FROM Patient", connection)

  Dim table As New DataTable()
  dataAdapter.Fill(table)

  Console.WriteLine("Contents of Patient.")

  For Each row As DataRow In table.Rows
    Console.WriteLine("{0}: {1}", row("Id"), row("[address-city]"))
  Next
End Using