Linq Search by Dictionary value

Question

I am trying to search contacts (Objects) that contains a List<Dictionary<string, string>> by a dictionary key and value

Below is my Json Array of Contacts

[
  {
    "first_name": "David",
    "last_name": "Smith",
    "email": "david@gmail.com",
    "phone": "1234567890",
    "website": "google.com",
    "relations": [
      {
        "listid": "65512fe1e759b98f40b48829"
      },
      {
        "listid": "34212fe1e759b98f40b48829"
      }
    ]
  },
  {
    "first_name": "Chris",
    "last_name": "Oven",
    "email": "chris@gmail.com",
    "phone": "1234567890",
    "website": "google.com",
    "relations": [
      {
        "listid": "65512fe1e759b98f40b48829"
      },
      {
        "listid": "34212fe1e759b98f40b48829"
      }
    ]
  }
]

I am trying to find all contacts that contain listid = "65512fe1e759b98f40b48829".

What is the best way to do this using Linq?

Tried something like below:

var searchPair = new KeyValuePair<string, string>("listid", "65512fe1e759b98f40b48829");

contacts.Where(p=>p.relations.Where(dictionary => dictionary[searchPair.Key].ToString().Contains(searchPair.Value)).ToList();

but somewhere it is giving incorrect way for searching

Answer 1

It seems to me that this is a better representation of your JSON:

public class Customer
{
    [JsonProperty("first_name")]
    public string FirstName { get; set; }

    [JsonProperty("last_name")]
    public string LastName { get; set; }

    [JsonProperty("email")]
    public string Email { get; set; }

    [JsonProperty("phone")]
    public string Phone { get; set; }

    [JsonProperty("website")]
    public string Website { get; set; }

    [JsonProperty("relations")]
    public List<Relation> Relations { get; set; }
}

public class Relation
{
    [JsonProperty("listid")]
    public string ListId { get; set; }
}

Now you can read in your data:

List<Customer> customers =
    Newtonsoft
        .Json
        .JsonConvert
        .DeserializeObject<List<Customer>>(
            File.ReadAllText(@"customers.json"));

That gives:

Now querying it is simple:

IEnumerable<Customer> query =
    from c in customers
    where c.Relations.Any(r => r.ListId == "65512fe1e759b98f40b48829")
    select c;

---

Here's the query if you use the dictionary version of relations you suggested:

IEnumerable<Customer> query =
    from c in customers
    where c.Relations.Any(r => r.TryGetValue("listid", out string value)
        && value == "65512fe1e759b98f40b48829")
    select c;