/// <summary>
/// 返回模型对应的主键字段名
/// </summary>
/// <returns>返回模型的主键列信息</returns>
internal static Expression <Func <T, bool> > GetKeysExpression <T>(T entity)
{
var keyMeta = MapperConfig.GetKeyMetas <T>();
if (keyMeta == null)
{
throw Error.Exception("没有为模型" + typeof(T).FullName + "指定主键。");
}
LambdaExpression body = null;
ParameterExpression parameter = null;
for (var i = 0; i < keyMeta.Length; i++)
{
var meta = keyMeta[i];
if (meta.Expression is LambdaExpression exp)
{
parameter = exp.Parameters.FirstOrDefault();
var key = exp.Compile().DynamicInvoke(entity);
var keyExp = Expression.Constant(key);
//var keyExp = Expression.MakeMemberAccess(constvar, meta.Member);
var mem = exp.Body.ChangeType(keyExp.Type);
var condition = Expression.Equal(keyExp, mem);
var innerLambda = Expression.Lambda(condition, parameter);
body = body.AndAlso(innerLambda);
}
}
if (body != null)
{
return(Expression.Lambda <Func <T, bool> >(body.Body, parameter));
}
return(null);
}
/// <summary>
/// 返回模型对应的主键字段名
/// </summary>
/// <returns>返回模型的主键列信息</returns>
internal static Expression <Func <T, bool> > GetKeysExpression <T>(params object[] keys)
{
var keyMeta = MapperConfig.GetKeyMetas <T>();
if (keyMeta == null)
{
throw Error.Exception("没有为模型" + typeof(T).FullName + "指定主键。");
}
if (keys.Length != keyMeta.Length)
{
return(null);
//throw Error.Exception("主键的列数目和给定的键值数目不相等。");
}
LambdaExpression body = null;
ParameterExpression parameter = null;
for (var i = 0; i < keyMeta.Length; i++)
{
var meta = keyMeta[i];
if (meta.Expression is LambdaExpression exp)
{
parameter = exp.Parameters.FirstOrDefault();
var keyExp = Expression.Constant(keys[i]);
var mem = exp.Body.ChangeType(keyExp.Type);
var condition = Expression.Equal(keyExp, mem);
var innerLambda = Expression.Lambda(condition, parameter);
body = body.AndAlso(innerLambda);
}
}
if (body != null)
{
return(Expression.Lambda <Func <T, bool> >(body.Body, parameter));
}
return(null);
}