NAME

SYNOPSIS

   use Tangram::Core;
   use Tangram::Type::Hash::Scalar; # always

   $schema = Tangram::Schema->new(
      classes => { NaturalPerson => { fields => {

      flat_hash =>
      {
         opinions =>
         {
            table => 'NP_ops',
            key_sql => 'VARCHAR(10)',
            type => 'int',
            sql => 'NUMERIC(1)',
         },

         lucky_numbers => 'int', # use defaults
      }

DESCRIPTION

The hash may contain as keys and values only 'simple' scalars like integers, strings or real numbers. It may not contain references. For hashs of objects, see Tangram::Type::Hash::FromMany and Tangram::Type::Hash::FromOne.

Tangram uses a table to save the state of the collection. The table has three columns, which contain

• the id of the container object
• the key of the element in the hash
• the value of the element

The field names are passed in a hash that associates a field name with a field descriptor. The field descriptor may be either a hash or a string. The hash uses the following fields:

• key_type
• key_sql
• type
• sql
• table

The optional fields "key_type" and "type" specify the key and value types of the hash. If the type is "string" Tangram quotes the values as they are passed to the database. Not specifying a "type" is exactly equivalent to specifying "string".

Optional field "table" sets the name of the table that contains the elements. This defaults to 'C_F', where C is the class of the containing object and F is the field name.

The optional fields "key_sql" and "sql" specify the type that deploy() (see Tangram::Deploy) should use for the column containing the key and value of the hash. If this field is not present, the SQL type is derived from the "type" field: if "type" is "string" (or is absent) VARCHAR(255) is used; otherwise, the "type" field is interpreted as a SQL type.

If the descriptor is a string, it is interpreted as the value of the "type" field and all the other fields take the default value.

AUTHOR