Commands and queries

Jerrycurl relies heavily on the command-query separation pattern, which ensures that your data-writing code is separated from your data-reading code.

Create relational input data from an object source, simulating SELECT.
Execute an SQL query or command referencing the input (i.e. parameters), outputting a number of IDataReader data sets.
Map output data back into your relational model by simulating INSERT (queries) and UPDATE (commands) operations.

// command
var command = connection.CreateCommand();

command.CommandText = "INSERT INTO ...";

// query
var query = connection.CreateCommand();

command.CommandText = "SELECT ... FROM";

Parameters

store.From(new Blog() { ... })
     .Select("Title", "CreatedOn")
     .AddParameters(command);

store.From(new BlogFilter() { ... })
     .Select("MinDate", "MaxDate")
     .AddParameters(query);

Queries

// query
var query = connection.CreateCommand();

query.CommandText = @"SELECT [Title] AS [Item.Title]
                       FROM [Blog]
                       WHERE CreatedOn BETWEEN @P0 AND @P1";

// parameters
var data = new BlogFilter { ... };

store.From(data)
     .Select("MinDate", "MaxDate")
     .AddParameters(query);

// buffer
var schema = store.GetSchema<List<Blog>>();
var buffer = new QueryBuffer(schema, QueryType.List);

buffer.Insert(dataReader);

var result = buffer.Commit<List<Blog>>();

Connections

var options = new QueryOptions
{
    ConnectionFactory = () => new SqlConnection("..."),
    Schemas = store,
};

var query = new Query
{
    QueryText = "SELECT ... FROM",
    Parameters = store.From(new BlogFilter() { ... })
                      .Select("MinDate", "MaxDate")
                      .AsParameters()
};

var engine = new QueryEngine(options);

var result = engine.List<Blog>(query);

Commands

// command data
var data = new Blog { ... };

store.From(data)
     .Select("Title", "CreatedOn")
     .AddParameters(command);

var buffer = new CommandBuffer();

using var dataReader = command.ExecuteReader();

buffer.UpdateAll(dataReader);
buffer.Commit();

Parameters

Bindings

Jerrycurl has three methods that can be used to get data back into your object:

A ParameterBinding works by setting the IDataParameter.Direction to output
A ColumnBinding
A CascadeBinding

Connections

var options = new CommandOptions
{
    ConnectionFactory = () => new SqlConnection("..."),
};

var data = new Blog() { ... };
var command = new Command
{
    CommandText = "INSERT INTO ...",
    Parameters = store.From(data)
                      .Select("Title", "CreatedOn")
                      .AsParameters(),
    Bindings = store.From(data)
                    .Select("Id")
                    .AsBindings(),
};

var engine = new CommandEngine(options);

engine.Execute(command);