/// <summary>
/// Save the specified data of <see cref="IInternalState"/> into database.
/// </summary>
/// <param name="query">The <see cref="IAdfQuery"/> that defines the datasource name and query statement.</param>
/// <param name="data">The data of <see cref="IInternalState"/> that needs to be saved.</param>
/// <returns>True if data is successfully saved; otherwise, false.
/// This method also returns false if <see cref="IAdfQuery"/> or <see cref="IInternalState"/> is null.</returns>
/// <exception cref="System.InvalidOperationException">The current state of the connection is closed.</exception>
/// <exception cref="System.Data.DBConcurrencyException">An attempt to execute an INSERT, UPDATE, or DELETE statement resulted in zero records affected.</exception>
public bool Save(IAdfQuery query, IInternalState data)
{
if (query == null) throw new ArgumentNullException("query");
if (data == null) throw new ArgumentNullException("data");
if (!data.IsAltered) return true;
var state = data as DictionaryState;
if (state == null) throw new InvalidOperationException("State is not a " + typeof(DictionaryState));
var table = query.Tables[0];
var q = new AdfQuery()
.From(table);
q.QueryType = state.IsNew ? QueryType.Insert : QueryType.Update;
foreach (var col in state)
{
if (col.Key.IsAutoIncrement || col.Key.IsTimestamp) continue; // auto increment fields are not saved
if (col.Key.IsIdentity && !state.IsNew) continue; // primary key is not saved when object is not new
q.Selects.Add(new Expression { Column = col.Key, Type = ExpressionType.Column });
q.Wheres.Add(new Where { Column = col.Key, Parameter = new Parameter(col.Value, ParameterType.QueryParameter) });
}
if (!state.IsNew)
{
var timestamp = state.Keys.FirstOrDefault(col => col.IsTimestamp);
if (timestamp == null) throw new InvalidOperationException("Cannot save this state as it does not have a timestamp");
q
.Where(timestamp).IsEqual(state[timestamp])
.Where(state.PrimaryKey).IsEqual(state[state.PrimaryKey]);
}
return RunSave(state, q);
}