nếu bạn đang sử dụng MS Sql, tôi đã viết 2 phương thức mở rộng để hỗ trợ ký tự% cho tìm kiếm theo ký tự đại diện. (LinqKit là bắt buộc)
public static class ExpressionExtension
{
public static Expression<Func<T, bool>> Like<T>(Expression<Func<T, string>> expr, string likeValue)
{
var paramExpr = expr.Parameters.First();
var memExpr = expr.Body;
if (likeValue == null || likeValue.Contains('%') != true)
{
Expression<Func<string>> valExpr = () => likeValue;
var eqExpr = Expression.Equal(memExpr, valExpr.Body);
return Expression.Lambda<Func<T, bool>>(eqExpr, paramExpr);
}
if (likeValue.Replace("%", string.Empty).Length == 0)
{
return PredicateBuilder.True<T>();
}
likeValue = Regex.Replace(likeValue, "%+", "%");
if (likeValue.Length > 2 && likeValue.Substring(1, likeValue.Length - 2).Contains('%'))
{
likeValue = likeValue.Replace("[", "[[]").Replace("_", "[_]");
Expression<Func<string>> valExpr = () => likeValue;
var patExpr = Expression.Call(typeof(SqlFunctions).GetMethod("PatIndex",
new[] { typeof(string), typeof(string) }), valExpr.Body, memExpr);
var neExpr = Expression.NotEqual(patExpr, Expression.Convert(Expression.Constant(0), typeof(int?)));
return Expression.Lambda<Func<T, bool>>(neExpr, paramExpr);
}
if (likeValue.StartsWith("%"))
{
if (likeValue.EndsWith("%") == true)
{
likeValue = likeValue.Substring(1, likeValue.Length - 2);
Expression<Func<string>> valExpr = () => likeValue;
var containsExpr = Expression.Call(memExpr, typeof(String).GetMethod("Contains",
new[] { typeof(string) }), valExpr.Body);
return Expression.Lambda<Func<T, bool>>(containsExpr, paramExpr);
}
else
{
likeValue = likeValue.Substring(1);
Expression<Func<string>> valExpr = () => likeValue;
var endsExpr = Expression.Call(memExpr, typeof(String).GetMethod("EndsWith",
new[] { typeof(string) }), valExpr.Body);
return Expression.Lambda<Func<T, bool>>(endsExpr, paramExpr);
}
}
else
{
likeValue = likeValue.Remove(likeValue.Length - 1);
Expression<Func<string>> valExpr = () => likeValue;
var startsExpr = Expression.Call(memExpr, typeof(String).GetMethod("StartsWith",
new[] { typeof(string) }), valExpr.Body);
return Expression.Lambda<Func<T, bool>>(startsExpr, paramExpr);
}
}
public static Expression<Func<T, bool>> AndLike<T>(this Expression<Func<T, bool>> predicate, Expression<Func<T, string>> expr, string likeValue)
{
var andPredicate = Like(expr, likeValue);
if (andPredicate != null)
{
predicate = predicate.And(andPredicate.Expand());
}
return predicate;
}
public static Expression<Func<T, bool>> OrLike<T>(this Expression<Func<T, bool>> predicate, Expression<Func<T, string>> expr, string likeValue)
{
var orPredicate = Like(expr, likeValue);
if (orPredicate != null)
{
predicate = predicate.Or(orPredicate.Expand());
}
return predicate;
}
}
sử dụng
var orPredicate = PredicateBuilder.False<People>();
orPredicate = orPredicate.OrLike(per => per.Name, "He%llo%");
orPredicate = orPredicate.OrLike(per => per.Name, "%Hi%");
var predicate = PredicateBuilder.True<People>();
predicate = predicate.And(orPredicate.Expand());
predicate = predicate.AndLike(per => per.Status, "%Active");
var list = dbContext.Set<People>().Where(predicate.Expand()).ToList();
trong ef6 và nó sẽ dịch sang
....
from People per
where (
patindex(@p__linq__0, per.Name) <> 0
or per.Name like @p__linq__1 escape '~'
) and per.Status like @p__linq__2 escape '~'
', @ p__linq__0 ='% He% llo% ', @ p__linq__1 ='% Hi% ', @ p__linq_2 ='% Active '