Question

I took a look at this answer and it goes in part to solving my issue.

However, what I need is the following.

Given I have an object;

Product
  string code
  List<suitability> items

and then i have this object;

Suitability
  key
  value

Each Product has a variable amount of [items] and the key/value pairs differ from product to product.

When searching I am given a list of Suitability objects. I now need to search all the products that contain (all) of the supplied suitability objects.

So for example a product may have dental = true and therapies = true.

I may get a request for all products that have dental = true and therapies = false.

Answer 1

Using PredicateBuilder (from the authors of LinqPad) you can build up a query from a set of conditions not known at compile time. The following should be sufficient:

var predicate = PredicateBuilder.True<Product>();

foreach (Suitability criteria in searchCriteria)
{
    string tempKey = criteria.Key;
    string tempValue = criteria.Value;
    predicate = predicate.And(p => 
                     p.Items.Any(s => s.Key == tempKey && s.Value == tempValue));
}

return dataContext.Products.Where(predicate.Compile());

UPDATE: Heres some sample code that I have tested which works using an IEnumerable as the source, the resulting set productsResult contains the first and second products in products list:

var searchCriteria = new List<Suitability>()
    {
        new Suitability() { Key="a", Value="b" },
        new Suitability() { Key="a", Value="c" }
    };

var products = new List<Product>()
    {
        new Product()
            {
                Items = new List<Suitability>() {
                            new Suitability() { Key="a", Value="b" },
                            new Suitability() { Key="a", Value="c" }}
            },
        new Product()
            {
                Items = new List<Suitability>() {
                            new Suitability() { Key="a", Value="b" },
                            new Suitability() { Key="a", Value="c" },
                            new Suitability() { Key="b", Value="c" }}
            },
        new Product()
            {
                Items = new List<Suitability>() {
                            new Suitability() { Key="c", Value="d" }}
            }
    };

    var predicate = PredicateBuilder.True<Product>();

    foreach (Suitability criteria in searchCriteria)
    {
        string tempKey = criteria.Key;
        string tempValue = criteria.Value;
        predicate = predicate.And(p => p.Items.Any(
                         s => s.Key == tempKey && s.Value == tempValue));
    }

    IEnumerable<Product> productsResult = products.Where(predicate.Compile());