/// <summary>
/// 如果不满足条件则创建一个实体，
/// 如限制用户名不能重复 InsertIfNotExist(user, u => u.Name == user.Name)
/// </summary>
/// <typeparam name="T"></typeparam>
/// <param name="entity">要创建的实体</param>
/// <param name="where">条件</param>
/// <returns>新生成记录的ID，若失败返回0</returns>
public int InsertIfNotExists <T>(T entity, Expression <Func <T, bool> > where) where T : class, IEntity, new()
{
if (where == null)
{
return(Insert(entity));
}
var entityInfo = MyEntityContainer.Get(typeof(T));
var resolver = new EditConditionResolver <T>(entityInfo);
var result = resolver.Resolve(@where.Body);
var condition = result.Condition;
var parameters = result.Parameters;
parameters.Add(entity);
condition = string.IsNullOrWhiteSpace(condition) ? "1=1" : condition;
var sqlBuilder = new SqlServerBuilder();
var sql = sqlBuilder.InsertIfNotExists(entityInfo, condition);
var command = new SqlCommand(sql);
command.Parameters.AddRange(parameters.Parameters);
using (var conn = new SqlConnection(_connectionString))
{
conn.Open();
command.Connection = conn;
var obj = command.ExecuteScalar();
if (obj != DBNull.Value)
{
entity.Id = Convert.ToInt32(obj);
}
return(entity.Id);
}
}