//public ValueCompare<TEntity> Create(Expression<Func<TEntity, bool>> where)
//{
// ExpressionBody = where;
// return this;
//}
public ValueCompare <TEntity> Create(Expression <Func <TEntity, bool> > filter)
{
var getterBody = _parameterRebinder.Visit(filter.Body);//统一参数
ExpressionBody = getterBody;
if (ExpressionBody == null)
{
throw new Exception("ExpressionBody为NULL");
}
return(this);
}
/// <summary>
/// Combines a sequence of expressions using the logical AND.
/// </summary>
/// <typeparam name="T">The type of parameter of the expressions.</typeparam>
/// <param name="expressions">The sequence of expressions to combine.</param>
/// <returns>
/// The combined expression.
/// </returns>
public static Expression <Func <T, bool> > And <T>(this IEnumerable <Expression <Func <T, bool> > > expressions)
{
if (expressions == null)
{
throw new ArgumentNullException(nameof(expressions),
$"Unable to compose And, {nameof(expressions)} parameter cannot be null");
}
if (!expressions.Any())
{
throw new ArgumentException($"Unable to compose And, {nameof(expressions)} parameter cannot be empty",
nameof(expressions));
}
var lambda = expressions.First();
var body = lambda.Body;
var parameter = lambda.Parameters[0];
foreach (var expression in expressions.Skip(1))
{
var visitor = new ParameterRebinder(expression.Parameters[0], parameter);
body = Expression.AndAlso(body, visitor.Visit(expression.Body));
}
lambda = Expression.Lambda <Func <T, bool> >(body, parameter);
return(lambda);
}
