Class Result

Namespace: YndigoBlue.Velocity.Model

Assembly: YndigoBlue.Velocity.dll

Represents a single row returned from a SELECT query.

public class Result : Datum

Inheritance: object

Datum

Result

Extension Methods: Extensions.GetFeature(Result, string, bool)

Remarks

Result is the primary object for working with query data. Each Result instance represents one row from the database, with strongly-typed access to column values through inherited Datum methods.

Results are returned as collections from Retrieve(Query) and can be:

Accessed field-by-field using GetField* methods
Bound to C# objects using BindResults<T>(BindingType)
Checked for NULL values using IsNull methods

Examples

Basic query and result access:

using (Manager manager = new Manager(connection))
{
    Schema schema = manager.LoadSchema("my_schema");
    Table usersTable = schema["users"];

    var query = new Query()
        .Select([ usersTable["id"], usersTable["username"], usersTable["email"], usersTable["created_at"] ])
        .From(usersTable);

    using (ResultSet results = manager.Retrieve(query))
    {
        foreach (Result result in results)
        {
            int id = result.GetFieldInt("id");
            string username = result.GetFieldString("username");
            string email = result.GetFieldString("email");
            DateTime createdAt = result.GetFieldDateTime("created_at");

            Console.WriteLine($"{id}: {username} ({email}) - {createdAt}");
        }
    }
}

Handling NULL values:

var query = new Query()
    .Select([ usersTable["id"], usersTable["last_login"] ])
    .From(usersTable);

using (ResultSet results = manager.Retrieve(query))
{
    foreach (Result result in results)
    {
        int id = result.GetFieldInt("id");

        if (result.IsNull(usersTable["last_login"]))
        {
            Console.WriteLine($"User {id} has never logged in");
        }
        else
        {
            DateTime lastLogin = result.GetFieldDateTime("last_login");
            Console.WriteLine($"User {id} last logged in: {lastLogin}");
        }
    }
}

Binding results to C# objects:

public class User
{
    public int Id { get; set; }
    public string Username { get; set; }
    public string Email { get; set; }
    public DateTime CreatedAt { get; set; }
}

var query = new Query()
    .Select([ usersTable["id"], usersTable["username"], usersTable["email"], usersTable["created_at"] ])
    .From(usersTable);

using (ResultSet results = manager.Retrieve(query))
{
    // Automatically bind results to User objects
    IList<User> users = results.BindResults<User>(BindingType.SnakeCase);

    foreach (User user in users)
    {
        Console.WriteLine($"{user.Id}: {user.Username}");
    }
}

Working with calculated fields:

Expression totalExpression = new Expression("total");
totalExpression.Add(ordersTable["quantity"]);
totalExpression.Add(new ArithmeticOperator(ArithmeticType.Multiply));
totalExpression.Add(ordersTable["price"]);

var query = new Query()
    .Select([ ordersTable["id"], totalExpression ])
    .From(ordersTable);

using (ResultSet results = manager.Retrieve(query))
{
    foreach (Result result in results)
    {
        int id = result.GetFieldInt("id");
        decimal total = result.GetFieldDecimal("total");
        Console.WriteLine($"Order {id}: ${total}");
    }
}

Constructors

Result(OrderedDictionary<string, ISelectItem>): Initializes a new Result with the ordered set of select items that describe the columns in this row.

Properties

FieldCount: Gets the number of columns in this result row.

Fields: Gets the ordered collection of select items (columns) that make up this result row.

Methods

GetFieldString(string): Gets the value of the specified field as an untyped string. Checks char and varchar columns as fallbacks if no string column is found.

GetFieldValue(string, DataType): Gets the value of a named field, returned as the CLR type that corresponds to dataType.

IsNull(ISelectItem): Determines if the select item is null within this datum either as a result of not being in the datum or being in the datum and being set to null.