Working with results — ds_result

Each result set returned by the data source is encapsulated by the ds_result type. The ds_result type provides access to information about the the result set and rows returned by the data source.

Typically when a data source is invoked one ds_result is generated. For convenience ds replicates most of the methods ds_result provides and directs them to the most recent ds_result.

Once invoked, the ds type can be queried directly as by default any ds_result sets are iterated:

	with result in my_ds->sql('
	    UPDATE products SET status = 2 WHERE status = 1;
	') do {
	    #result->affected   // Number of rows affected
	    #result->found 	// Number of rows found
	}

Result set information

-> columns::staticarray

Returns the columns names returned by the data source.

-> found::integer

Returns the number of rows found.

-> affected::integer

Returns the number of rows affected by an update, insert or delete.

-> num::integer

Returns the result sets number within the current set.

Accessing result set rows

-> rows::staticarray

Returns staticarray containing the ds_rows returned by the data source.

-> rows(astype::tag)::staticarray

Returns staticarray containing the specified type created with each ds_row — this is a really fast efficient approach to OOP (the overhead is minimal). Any type that supports ->oncreate(p::ds_row) can be returned in this way.

with product in result->rows(::product) do {
   #product->isa(::product) // true
}

In the above example each row will be encapsulated by the product type — a custom type which inherits activerow. This is achieved by specifying activerow as the parent of the product type. From there you can modify and extend the product type as required.

-> rows(invokewith::memberstream)::staticarray

The supplied memberstream will be invoked for each ds_row with the ds_row as the parameter, the results will be returned in a staticarray.

with product in result->rows(\product) do {
   #product->isa(::product) // true
}

Working with multiple result sets

However some data sources can generate multiple ds_result sets depending on the number of result sets returned by the data source.

	with result in my_ds->sql('
	    UPDATE products SET status = 2 WHERE status = 1;
	    SELECT * FROM products WHERE status = 2;
	') do {
	    #result->affected     // Number of rows affected
	    #result->found 	  // Number of row found
	}

ds_result sets can also be accessed and stored by calling '->results'.

	local(
	    ds = ds(::store.products),
	    sql = 'UPDATE products SET status = 2 WHERE status = 1;
		   SELECT * FROM products WHERE status = 2',
	    results = #ds->sql(#sql)->results
	)
	with result in #results do {
	    #result->affected ? #ds->do_something
	    #result->found    ? #ds->do_something_else
	}

Result set helper

When ds is provided a capture in a similar fashion to inline the result helper returns either the current ds_result or a specified ds_result if multiple result sets are available. Simply call result within the supplied capture like so:

	ds(::store.products)->all => {
	    result->found // found count
	    result->rows  // rows to work with
	}

	inline(-database='store',-table='products',-findall) => {
	    result->found // found count
	    result->rows  // rows to work with
	}

Specific ds_result sets can retrieved by the helper by specifying an integer:

	ds(::store.products)->sql('
	    UPDATE products SET status = 2 WHERE status = 1;
	    SELECT * FROM products WHERE status = 2;
	') => {
	    result(1)->affected // number of rows affected by UPDATE
	    result(2)->rows 	// rows returned by SELECT
	}