字符串“未定义”未被识别为有效的日期时间。 有一个从索引“0”开始的未知单词

Question

I have a C#.Net backend and I am querying a cosmos DB for an item that meets a certain criteria. A user will select an image if they want to set it as the thumbnail when they do it will trigger this to find the original thumbnail to unset the IsThumbnail attribute.

Here is the LINQ statement (The error occurs here):

var current = _context.LandImages.AsEnumerable()
                    .Where(li => li.LandId == image.LandId)
                    .FirstOrDefault(li => li.IsThumbnail.HasValue && li.IsThumbnail.Value && li.BlobUri.Contains("/land-images/"));

And here is the data entry in cosmos:

{
    "Id": "d0b55439-2ba8-4984-80d5-a1d5d97c95bc",
    "BlobUri": "https://blobStorageurl.windows.net/land-images/e5a7cfca-f0ac-4fcb-9c42-7cc27ffe2caf/d0b55439-2ba8-4984-80d5-a1d5d97c95bc",
    "Caption": null,
    "CreatedDate": "2022-01-11T18:40:15.3924032Z",
    "Discriminator": "LandImage",
    "IsThumbnail": true,
    "LandId": "e5a7cfca-f0ac-4fcb-9c42-7cc27ffe2caf",
    "PartitionKey": "e5a7cfca-f0ac-4fcb-9c42-7cc27ffe2caf",
    "Status": "Uploaded",
    "UpdatedDate": "2022-01-11T18:40:15.5743165Z",
    "id": "LandImage|d0b55439-2ba8-4984-80d5-a1d5d97c95bc",
    "_rid": "X9EjAMtaj1dNHgAAAAAAAA==",
    "_self": "dbs/X9EjAA==/colls/X9EjAMtaj1c=/docs/X9EjAMtaj1dNHgAAAAAAAA==/",
    "_etag": "\"ee05d6cb-0000-0300-0000-61ddcf0f0000\"",
    "_attachments": "attachments/",
    "_ts": 1641926415
}

I don't see anything as undefined so I am having trouble understanding this error message.

Answer 1

you have repeated li.IsThumbnail.HasValue several times. Try this

var current = _context.LandImages
                     .Where(li => li.LandId == image.LandId
                      && ( li.IsThumbnail!=null && ((bool)li.IsThumbnail==true))
                      && li.BlobUri.Contains("/land-images/"))
                      .FirstOrDefault();