linq - How do I use Entity Framework to find a record in Cosmos with case insensitive conditions

Question

I know tis question has been asked several times on SO but I haven't found a solution that works. It's clear that Cosmos is capable of case insensitive searches since June 2020 but I haven't managed to find a solution that works with EF.

For example...

await objDbContext.Tags.SingleOrDefaultAsync(t => t.Value.Equals("value", StringComparison.InvariantCultureIgnoreCase))

... throws the following exception:

System.InvalidOperationException: 'The LINQ expression 'DbSet() .Where(t => t.Value.Equals( value: "Value", comparisonType: InvariantCultureIgnoreCase))' could not be translated. Additional information: Translation of the 'string.Equals' overload with a 'StringComparison' parameter is not supported. See https://go.microsoft.com/fwlink/?linkid=2129535 for more information. Either rewrite the query in a form that can be translated, or switch to client evaluation explicitly by inserting a call to 'AsEnumerable', 'AsAsyncEnumerable', 'ToList', or 'ToListAsync'. See https://go.microsoft.com/fwlink/?linkid=2101038 for more information.'

I've also tried .ToLower and string.Equals with similar results.

Is there a right way to do it? If not, is there an alternative? I'm happy to store the value in lowercase along side the actual value, to be used for searching only, but it must be updated automatically.

question from:https://stackoverflow.com/questions/65887302/how-do-i-use-entity-framework-to-find-a-record-in-cosmos-with-case-insensitive-c

Answer 1

EF Core 5 has now implemented the transactions. Once you have updated you can change this line

await objDbContext.Tags.SingleOrDefaultAsync(t => t.Value.Equals("value", StringComparison.InvariantCultureIgnoreCase));

to

await objDbContext.Tags.SingleOrDefaultAsync(t => t.Value.ToLower() == "value");