/// <summary>
/// 从一个对象实例中通过检查DbTable和DbField特性来构建一个用于插入数据行的T-SQL语句。
/// 为了防止SQL注入，该SQL语句是参数化的，并且通过out参数返回由entity对象实例中包括的值构建出来的SqlParameter集
/// </summary>
/// <param name="entity">准备用作插入新行的对象实例</param>
/// <param name="parameters">参数化的每一列输入参数，包含了值</param>
/// <param name="primaryKey">主键输出参数，用来返回新行的主键</param>
/// <returns></returns>
static string BuildInsertSql(object entity, out SqlParameter[] parameters, out SqlParameter primaryKey)
{
Type type = entity.GetType();
object[] tableAttributes = type.GetCustomAttributes(typeof(DbTableAttribute), false);
if (tableAttributes == null || tableAttributes.Length != 1)
{
throw new Exception("使用BuildInsertSql()方法，类" + type.FullName + "必须标记唯一的DbTable特性。");
}
DbTableAttribute tableAttr = (DbTableAttribute)tableAttributes[0];
StringBuilder fieldBuilder = new StringBuilder(), valueBuilder = new StringBuilder();
List <SqlParameter> parametersList = new List <SqlParameter>();
primaryKey = null;
foreach (MemberInfo m in type.GetMembers(BindingFlags.Instance | BindingFlags.Public))
{
#region loop values
bool isDefine = m.IsDefined(typeof(DbFieldAttribute), false);
if (!isDefine)
{
continue;
}
DbFieldAttribute fldAttr = (DbFieldAttribute)(DbFieldAttribute.GetCustomAttribute(m, typeof(DbFieldAttribute)));
if (fldAttr.IsPrimaryKey)
{
primaryKey = new SqlParameter("@" + fldAttr.FieldName, SqlDbType.Int)
{
Direction = ParameterDirection.Output
};
parametersList.Add(primaryKey);
continue;
}
if ((fldAttr.Usage & DbFieldUsage.InsertParameter) != DbFieldUsage.InsertParameter)
{
continue;
}
fieldBuilder.Append(",[" + fldAttr.FieldName + "]");
valueBuilder.Append(",@" + fldAttr.FieldName);
Type memberType;
object memberValue = ValueHelper.GetMemberValue(m, fldAttr, entity, out memberType);
SqlParameter parameter = GenerateSqlParameter(fldAttr, memberType, memberValue);
parametersList.Add(parameter);
#endregion
}
fieldBuilder.Remove(0, 1);
valueBuilder.Remove(0, 1);
string sql = @$ "
INSERT INTO {tableAttr.TableName}({fieldBuilder.ToString()}) VALUES({valueBuilder.ToString()});
/// <summary>
/// 使用关键字id从数据库中查找，返回entityType类的实例
/// </summary>
/// <param name="connector"></param>
/// <param name="entityType"></param>
/// <param name="id"></param>
/// <returns></returns>
public static async Task <T> FindEntity <T>(DbConnector connector, int id) where T : new()
{
Type entityType = typeof(T);
object[] tableAttributes = entityType.GetCustomAttributes(typeof(DbTableAttribute), false);
if (tableAttributes == null || tableAttributes.Length != 1)
{
throw new Exception("使用FindEntity()方法，类" + entityType.FullName + "必须标记唯一的DbTable特性。");
}
DbTableAttribute tableAttr = (DbTableAttribute)tableAttributes[0];
string tableName = tableAttr.TableName;
string keyName = string.Empty;
foreach (PropertyInfo propertyInfo in entityType.GetProperties())
{
if (!propertyInfo.IsDefined(typeof(DbFieldAttribute), false))
{
continue;
}
DbFieldAttribute fldAttr = (DbFieldAttribute)(DbFieldAttribute.GetCustomAttribute(propertyInfo, typeof(DbFieldAttribute)));
if (fldAttr.IsPrimaryKey)
{
keyName = fldAttr.FieldName;
break;
}
}
string sql = string.Format(@"SELECT * FROM {0} WHERE {1}={2};", tableName, keyName, id);
DataTable table = await connector.ExecuteSqlQueryTable(sql);
if (table == null || table.Rows.Count == 0)
{
return(default(T));
}
else
{
object obj = Activator.CreateInstance(entityType);
ValueHelper.FulfillEntity(entityType, table.Rows[0], ref obj);
return((T)obj);
}
}
/// <summary>
/// 使用row中的值填充对象entity
/// </summary>
/// <param name="type"></param>
/// <param name="row"></param>
/// <param name="entity"></param>
public static void FulfillEntity(Type type, DataRow row, ref object entity)
{
foreach (MemberInfo m in type.GetMembers(BindingFlags.Instance | BindingFlags.Public))
{
Attribute attr = DbFieldAttribute.GetCustomAttribute(m, typeof(DbFieldAttribute));
if (attr == null)
{
continue;
}
DbFieldAttribute dAttr = (DbFieldAttribute)attr;
if ((dAttr.Usage & DbFieldUsage.MapResultTable) != DbFieldUsage.MapResultTable)
{
continue;
}
try
{
if (m.MemberType == MemberTypes.Field)
{
//the member is a DbField;
object value = ValueHelper.GetTableRowValue(row, dAttr.FieldName, ((FieldInfo)m).FieldType);
((FieldInfo)m).SetValue(entity, value);
}
else if (m.MemberType == MemberTypes.Property)
{
//the member is a DbField;
object value = GetTableRowValue(row, dAttr.FieldName, ((PropertyInfo)m).PropertyType);
((PropertyInfo)m).SetValue(entity, value, null);
}
}
catch (Exception ex)
{
throw new Exception("成员[" + m.Name + "]出错" + ex.ToString());
}
}
}
/// <summary>
/// 使用提供的条件查询数据库（表由entityType指定），返回满足条件的记录（分页）
/// </summary>
/// <typeparam name="T">要查询的实体类型，标记了DbTable和DbField特性的类，并且具有空白构造函数</typeparam>
/// <param name="connector"></param>
/// <param name="criteria">查询条件字典，键是PropertyName，条件仅支持=比较，条件间仅支持AND运算</param>
/// <param name="pageIndex">从0开始的返回页索引</param>
/// <param name="pageSize">每页几行记录</param>
/// <param name="sortProperty">用于排序的PropertyName(如为空则使用关键字)</param>
/// <param name="descending">是否倒序排列</param>
/// <param name="total">符合条件的记录总数</param>
/// <returns></returns>
public static async Task <PagedQuery <T> > SearchEntities <T>(DbConnector connector, Dictionary <string, object> criteria,
int pageIndex, int pageSize, string sortProperty, bool descending) where T : new()
{
Type entityType = typeof(T);
if (!(DbTableAttribute.GetCustomAttribute(entityType, typeof(DbTableAttribute)) is DbTableAttribute tableAttr))
{
throw new Exception("类型" + entityType.FullName + "没有标记DbTableAttribute特性");
}
string selectClause = "SELECT * ";
string fromClause = "FROM " + tableAttr.TableName;
string orderBy;
#region 正确处理orderBy
DbFieldAttribute sortFieldAttr = null;
if (string.IsNullOrWhiteSpace(sortProperty))
{
//如果没有传递sortProperty参数, 则使用PrimaryKey
foreach (PropertyInfo property in entityType.GetProperties())
{
DbFieldAttribute fldAttr = DbFieldAttribute.GetCustomAttribute(property, typeof(DbFieldAttribute)) as DbFieldAttribute;
if (fldAttr != null && fldAttr.IsPrimaryKey)
{
sortFieldAttr = fldAttr;
break;
}
}
}
else
{
PropertyInfo property = entityType.GetProperty(sortProperty);
if (property == null)
{
throw new Exception(string.Format("类型{0}中没有找到{1}属性用于排序", entityType.FullName, sortProperty));
}
sortFieldAttr = DbFieldAttribute.GetCustomAttribute(property, typeof(DbFieldAttribute)) as DbFieldAttribute;
}
if (sortFieldAttr == null)
{
throw new Exception("类型" + entityType.FullName + "没有标记IsPrimaryKey=true的DbField特性");
}
if (descending)
{
orderBy = sortFieldAttr.FieldName + " DESC";
}
else
{
orderBy = sortFieldAttr.FieldName;
}
#endregion
StringBuilder whereBuilder = new StringBuilder();
List <SqlParameter> sqlParameters = new List <SqlParameter>();
if (criteria != null)
{
foreach (string conditionName in criteria.Keys)
{
if (criteria[conditionName] == null || criteria[conditionName].ToString().Length == 0)
{
continue;
}
PropertyInfo conditionProperty = entityType.GetProperty(conditionName);
if (conditionProperty == null)
{
throw new Exception(string.Format("类型{0}中没有找到{1}属性用于查询条件", entityType.FullName, conditionName));
}
DbFieldAttribute conditionAttr = DbFieldAttribute.GetCustomAttribute(conditionProperty, typeof(DbFieldAttribute)) as DbFieldAttribute;
if (conditionAttr == null)
{
throw new Exception(string.Format("类型{0}的{1}属性没有标记DbFieldAttribute特性, 无法用于数据库查询",
entityType.FullName, conditionName));
}
SqlParameter parameter = GenerateSqlParameter(conditionAttr, conditionProperty.PropertyType, criteria[conditionName]);
sqlParameters.Add(parameter);
whereBuilder.AppendFormat("[{0}]=@{0} ", conditionAttr.FieldName);
whereBuilder.Append("AND ");
}
}
if (whereBuilder.Length > 0)
{
whereBuilder.Remove(whereBuilder.Length - 4, 4);
}
string sql = BuildPagedSelectSql(selectClause, fromClause, whereBuilder.ToString(), orderBy, pageIndex, pageSize);
DataSet ds = await connector.ExecuteSqlQuerySet(sql, sqlParameters.ToArray());
PagedQuery <T> result = new PagedQuery <T>();
if (ds != null && ds.Tables.Count == 2)
{
result.Total = (int)ds.Tables[0].Rows[0][0];
ds.Tables[1].TableName = "result";
result.Records = await Task.Run(() => ValueHelper.WrapEntities <T>(ds.Tables[1]));
}
else
{
result.Total = 0;
result.Records = new T[0];
}
ds.Dispose();
return(result);
}