public async Task<List<string>> Get(string appId, string itemId, string relation, string userId)
{
using (var conn = new CqlConnection(_connString))
{
await conn.OpenAsync().ConfigureAwait(false);
var query = string.Format(
System.Globalization.CultureInfo.InvariantCulture,
"select values from negrapi.relations where app_id = '{0}' and item_id='{1}' and relation='{2}';",
appId,
GetKey(itemId, userId),
relation);
var cmd = new CqlCommand(
conn,
query,
CqlConsistency.One);
var result = await cmd.ExecuteScalarAsync().ConfigureAwait(false) as string;
if (string.IsNullOrEmpty(result))
{
return null;
}
var list = JsonConvert.DeserializeObject<List<RecommendationsDataValue>>(result);
return list
.Select(i => i.ItemId)
.ToList();
}
}
public async Task SelectScalarNoValue()
{
//Assume
const string retrieveCql = @"select value from Test.BasicFlow where id=10001;";
//Act
using(var connection = new CqlConnection(ConnectionString))
{
await connection.OpenAsync();
//select data
var selectCmd = new CqlCommand(connection, retrieveCql, CqlConsistency.One);
string value = (string)await selectCmd.ExecuteScalarAsync();
//if row does not exist value should be null
Assert.IsNull(value);
}
}
public async Task SelectScalarNullValue()
{
//Assume
const string insertCql = @"insert into Test.BasicFlow (id) values (2001);";
const string retrieveCql = @"select value from Test.BasicFlow where id=2001;";
//Act
using(var connection = new CqlConnection(ConnectionString))
{
await connection.OpenAsync();
//insert data
var cmd = new CqlCommand(connection, insertCql, CqlConsistency.One);
await cmd.ExecuteNonQueryAsync();
//select data
var selectCmd = new CqlCommand(connection, retrieveCql, CqlConsistency.One);
object value = await selectCmd.ExecuteScalarAsync();
Assert.AreEqual(DBNull.Value, value);
}
}
public async Task BasicInsertSelectScalar()
{
//Assume
const string insertCql = @"insert into Test.BasicFlow (id,value) values (1001,'Hallo 1001');";
const string retrieveCql = @"select value from Test.BasicFlow where id=1001;";
//Act
using(var connection = new CqlConnection(ConnectionString))
{
await connection.OpenAsync();
//insert data
var cmd = new CqlCommand(connection, insertCql, CqlConsistency.One);
await cmd.ExecuteNonQueryAsync();
//select data
var selectCmd = new CqlCommand(connection, retrieveCql, CqlConsistency.One);
string value = (string)await selectCmd.ExecuteScalarAsync();
Assert.AreEqual("Hallo 1001", value);
}
}