Question

Typically a dynamic linq query with string can use a substitution value such as:

result =
    db.Persons.Where("Name == @1", "John");

I have an unknown number of strings that I want to pass into the Where clause. I have no problem with integers, but the API cannot seem to handle a string without a substitution value.

Does anyone know a way around this? I created a concatenated string for my Where statement, so I can add “@1” or whatever, but I cannot add parameters to the Where() so I am stuck.

Thanks!

Answer 1

I creating a concatenated string for my where statement, so i can add “@1” or whatever, but I cannot add parameters to the Where() so I am stuck.

Yes, you can. The second argument of the Where method is params object[] values, so you just need to pass an array of objects.

For instance, assuming you have the property names and values in a dictionary, you could do something like this:

var dic = new Dictionary<string, object>
{
    { "Name", "John" },
    { "Age", 30 },
    { "City", "New York" }
};

...

var conditions = dic.Keys.Select(
    (key, idx) =>
        string.Format("{0} == @{1}", key, idx));
string predicate = string.Join(" And ", conditions);
object[] values = dic.Values.ToArray();
result = db.Persons.Where(predicate, values);