Mongodb C# driver Perform string contains query on a property in an embedded document

Question

I have the below simplified model:

public class Entity
{
    public Guid Id { get; set; }

    public IList<ComponentProperty> Components { get; private set; }

}

public class ComponentProperty
{
    public string PropertyName { get; set; }

    public string Value { get; set; }

}

I want to be able to find any entity whose property value string contains the search string, and to that end I wrote the following query, based on recommendation here, which implicitly uses Regex:

var query = _context.GetCollection<Entity>()
                        .AsQueryable()
                        .Where(t => t.Components.Any(c => c.Value.ToLower() == queryOptions.Filter));

This query produces the following json, and (incorrectly) returns 0 rows:

aggregate([{ "$match" : { "Components" : { "$elemMatch" : { "Value" : /^'green'$/i} } } }])

However, the hand-crafted query that produces the correct results is the below:

aggregate([{ "$match" : { "Components" : { "$elemMatch" : { "Value" :  {$regex: '.*green.*' } } } } }])

Perhaps, there is something I have overlooked in my approach using the c# driver, and any pointers will be much appreciated.

Answer 1

change your where clause to this:

.Where(e => e.Components.Any(c => c.Value.ToLower().Contains(queryOptions.Filter)))

which produces this aggregation:

db.Entity.aggregate([
    {
        "$match": {
            "Components.Value": /green/is
        }
    }
])

here's a test program:

using MongoDB.Entities;
using MongoDB.Entities.Core;
using System.Collections.Generic;
using System.Linq;

namespace StackOverFlow
{
    public class Ntity : Entity
    {
        public IList<ComponentProperty> Components { get; set; }
    }

    public class ComponentProperty
    {
        public string PropertyName { get; set; }

        public string Value { get; set; }

    }

    public static class Program
    {
        private static void Main()
        {
            new DB("test");

            new Ntity
            {
                Components = new List<ComponentProperty> {
                    new ComponentProperty {
                        PropertyName = "test",
                        Value = "the RED color" }
                }
            }.Save();

            new Ntity
            {
                Components = new List<ComponentProperty> {
                    new ComponentProperty {
                        PropertyName = "test",
                        Value = "the Green color" }
                }
            }.Save();

            var result = DB.Queryable<Ntity>()
                           .Where(e => e.Components.Any(c => c.Value.ToLower().Contains("green")))
                           .ToList();
        }
    }
}