How to get value from a parent class and a nested array child using linq?

Question

I have the following model to get data from database:

    public class CultureResource
    {
        public string KeyName { get; set; }
        public List<Resource> Resources { get; set; }
    }

    public class Resource
    {
        public string Value { get; set; }
        public string Culture { get; set; }
    }

Now my goal is to get data for a list of keys & culture where keys matches with CultureResource.KeyName & culture matches with Resource.Culture. How can I write a linq query on a IQueryable<CultureResource> to get a result of IList<Result> where Result may look like the following:

public class Result
{
    public string KeyName {get; set;}
    public string Value {get; set;}
}

I have tried the following Linq, but it throws $project or $group does not support {document}. error:

public IDictionary<string, string> GetLocalizedValueList(string[] keys, string culture)
{
    // returns IQueryable<CultureResource>
    var cultureResources = _repository.GetItems<CultureResource>();     

    /***** This is the query *********/
    var query = from cr in cultureResources
              from r in cr.Resources
              where keys.Contains(cr.KeyName) && r.Culture == culture
              select new { cr.KeyName, r.Value };
              
    var result = query.ToList()
              
    //return some data
}

FYI: my underlying database is mongo

Levanan Gan · Accepted Answer · 2021-11-03 16:45:14Z

0

How about this

        var query = cultureResources.SelectMany(cultureResource => cultureResource.Resources.Select(resource => new { cultureResource.KeyName, resource.Value })).ToList();

answered Nov 3, 2021 at 16:45

Levanan Gan

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2 Comments

SZT Over a year ago

This one doesn't check against culture or key

Levanan Gan Over a year ago

Ok get you, can try this

var query = cultureResources.Where(cultureResource => keys.Contains(cultureResource.KeyName))             .SelectMany(cultureResource => cultureResource.Resources.Where(resource=>resource.Culture==culture)             .Select(resource => new { cultureResource.KeyName, resource.Value })).ToList();

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