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PgSql: escape % and _ in Contains/StartsWith (ILIKE) #61

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Merged
AhmadRAbuhussein merged 1 commit into from
Oct 13, 2026
Merged

PgSql: escape % and _ in Contains/StartsWith (ILIKE) #61

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45 changes: 24 additions & 21 deletions SW.EfCoreExtensions.PgSql/ExpressionExtensions.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -55,29 +55,10 @@ static Expression BuildFilterExpression<TEntity>(this Expression parameter, ISea
switch (filter.Rule)
{
case SearchyRule.StartsWith:
//MethodInfo iLikeMethod = typeof(NpgsqlDbFunctionsExtensions).GetMethod("ILike", BindingFlags.NonPublic | BindingFlags.Public | BindingFlags.Static);

return Expression.Call(
typeof(NpgsqlDbFunctionsExtensions),
nameof(NpgsqlDbFunctionsExtensions.ILike),
Type.EmptyTypes,
Expression.Property(null, typeof(EF), nameof(EF.Functions)),
fieldNameExpression,
Expression.Constant($"{filter.Value}%")
);

//return Expression.Call(fieldNameExpression, typeof(string).GetMethod("StartsWith", new Type[] { typeof(string) }), GetValueAsConstantExpression(filter.Value, fieldType));
return BuildILikeExpression(fieldNameExpression, $"{EscapeLikePattern(filter.Value)}%");

case SearchyRule.Contains:

return Expression.Call(
typeof(NpgsqlDbFunctionsExtensions),
nameof(NpgsqlDbFunctionsExtensions.ILike),
Type.EmptyTypes,
Expression.Property(null, typeof(EF), nameof(EF.Functions)),
fieldNameExpression,
Expression.Constant($"%{filter.Value}%")
);
return BuildILikeExpression(fieldNameExpression, $"%{EscapeLikePattern(filter.Value)}%");

case SearchyRule.EqualsTo:
return Expression.Equal(fieldNameExpression, GetValueAsConstantExpression(filter.Value, fieldType));
Expand Down Expand Up @@ -119,6 +100,28 @@ static Expression BuildFilterExpression<TEntity>(this Expression parameter, ISea
}
}

// The value is escaped so a '%' or '_' in it matches literally, as string.Contains/StartsWith
// do. The escape character has to be passed explicitly: ILike without one makes Npgsql emit
// ESCAPE '', which turns escaping off altogether.
const string LikeEscapeCharacter = "\\";

static Expression BuildILikeExpression(Expression fieldNameExpression, string pattern) =>
Expression.Call(
typeof(NpgsqlDbFunctionsExtensions),
nameof(NpgsqlDbFunctionsExtensions.ILike),
Type.EmptyTypes,
Expression.Property(null, typeof(EF), nameof(EF.Functions)),
fieldNameExpression,
Expression.Constant(pattern),
Expression.Constant(LikeEscapeCharacter)
);

static string EscapeLikePattern(object value) =>
$"{value}"
.Replace(LikeEscapeCharacter, LikeEscapeCharacter + LikeEscapeCharacter)
.Replace("%", LikeEscapeCharacter + "%")
.Replace("_", LikeEscapeCharacter + "_");

static Expression GetValueAsConstantExpression(object value, Type type)
{
Expression constantExpression = Expression.Constant(value.ConvertValueToType(type));
Expand Down
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