Querying CosmosDB_SQL from ASP.NET Core 8 Web API to return Single value

Question

I want to return single value from an ASP.NET Core 8 Web API method:

public async Task<Driver> GetDriverByIdAsync(string id)
{
    var queryDefinition = new QueryDefinition($"SELECT * FROM c WHERE c.id = '{id}'");
    var queryResult = await _container.GetItemQueryIterator<Driver>(queryDefinition).ReadNextAsync();

    return queryResult.FirstOrDefault();
}

This method works fine and returns all data by provided id, but I want a single property value like name.

I tried this:

    public async Task<string> GetDriverByIdAsync2(string id)
    {
        var queryDefinition = new QueryDefinition($"SELECT c.name FROM c WHERE c.id = '{id}'");
        var queryResult = await _container.GetItemQueryIterator<string>(queryDefinition).ReadNextAsync();

        return queryResult.FirstOrDefault();
    }

but it does not work.

How should I correct this code for it to return only a single property value?

What is the right method to make it return only a single property value?

Answer 1

Have you tried something like this:

You are creating an object (Item) with a matching property (name). For GetItemQueryIterator you are using that data type to bind on.

public class Item
{
   public string name {get; set;}
}

public async Task<string> GetDriverByIdAsync2(string id)
    {
        var queryDefinition = new QueryDefinition($"SELECT c.name FROM c WHERE c.id = '{id}'");
        var queryResult = await _container.GetItemQueryIterator<Item>(queryDefinition).ReadNextAsync();

        return queryResult.FirstOrDefault().name;
    }