Issue with Nullable Guid Parsing

[ThomasKolarik]

Hello,

In version 0.4.2 there was a fix to parsing nullable enums (#315). However, I am running into a similar issue with nullable guids.

Here is a code sample to demonstrate what is going on, on my end.

    [Document(StorageType = StorageType.Json)]
    public class ItemEntry
    {
        [RedisIdField]
        public Guid Id { get; set; }

        public string Data { get; set; }
    }
    
    private readonly IRedisCollection<ItemEntry> items;
    
    public async Task<ItemEntry> FetchItemAsync(Guid? itemId)
    {
        var items = await this.items.Where(a => a.Id == itemId).ToListAsync();
        
        return items.FirstOrDefault();
    }

Which when called will error out with the follow exception,

  System.ArgumentException:
     at System.Enum.ValidateRuntimeType (System.Private.CoreLib, Version=6.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e)
     at System.Enum.TryParse (System.Private.CoreLib, Version=6.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e)
     at System.Enum.TryParse (System.Private.CoreLib, Version=6.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e)
     at Redis.OM.Common.ExpressionTranslator.TranslateBinaryExpression (Redis.OM, Version=0.6.0.0, Culture=neutral, PublicKeyToken=null)
     at Redis.OM.Common.ExpressionTranslator.BuildQueryFromExpression (Redis.OM, Version=0.6.0.0, Culture=neutral, PublicKeyToken=null)
     at Redis.OM.Searching.RedisCollectionEnumerator`1..ctor (Redis.OM, Version=0.6.0.0, Culture=neutral, PublicKeyToken=null)
     at Redis.OM.Searching.RedisCollection`1.GetAsyncEnumerator (Redis.OM, Version=0.6.0.0, Culture=neutral, PublicKeyToken=null)
     at Redis.OM.Searching.RedisCollection`1+<ToListAsync>d__40.MoveNext (Redis.OM, Version=0.6.0.0, Culture=neutral, PublicKeyToken=null))

As you can see in the error log, I am currently using version 0.6.0.

[slorello89]

Hi @ThomasKolarik,

This is a bit of an odd error (it looks like it's encountering some of the enum parsing logic which is unexpected). However this is actually an erroneous query. For several reasons:

1. The Id field is not indexed (you need to mark it as indexed in order to be able to do the LINQ style queries on it)
2. A nullable GUID is not a valid field to do a search on even if it were indexed. RediSearch has no concept (at the moment) of a nulled out field, hence it will not be able to interpret it.
3. You are using the GUID as your ID field, so you can just do an Id Search.

e.g.

    [Document(StorageType = StorageType.Json)]
    public class ItemEntry
    {
        [RedisIdField]
        [Indexed]
        public Guid Id { get; set; }

        public string Data { get; set; }
    }
    
    private readonly IRedisCollection<ItemEntry> items;
    
    public async Task<ItemEntry> FetchItemAsync(Guid? itemId)
    {
        if(itemId.HasValue)
            return await this.items.FirstOrDefaultAsync(a => a.Id == itemId.Value);
        else
            return default;
        // OR
        return await this.items.FindByIdAsync(itemId.Value.ToString());
    }