metapensiero.sqlalchemy.dbloady 1.2

author:

Lele Gaifax

contact:

lele@metapensiero.it

license:

GNU General Public License version 3 or later

Load new instances in the database, or update/delete existing ones, given a data structure represented by a YAML stream, as the following:

- entity: gam.model.Fascicolo
  key: descrizione
  # no data, just "declare" the entity

- entity: gam.model.TipologiaFornitore
  key: tipologiafornitore
  data:
    - &tf_onesto
      tipologiafornitore: Test fornitori onesti

- entity: gam.model.ClienteFornitore
  key: descrizione
  data:
    - descrizione: Test altro fornitore onesto
      tipologiafornitore: *tf_onesto
      partitaiva: 01234567890
    - &cf_lele
      codicefiscale: GFSMNL68C18H612V
      descrizione: Dipendente A

- entity: gam.model.Dipendente
  key: codicefiscale
  data:
    - &lele
      codicefiscale: GFSMNL68C18H612V
      nome: Emanuele
      cognome: Gaifas
      clientefornitore: *cf_lele
      foto: !File {path: ../img/lele.jpg}

- entity: gam.model.Attrezzature
  key: descrizione
  data:
    - &macchina
      descrizione: Fiat 500

- entity: gam.model.Prestiti
  key:
    - dipendente
    - attrezzatura
  data:
    - dipendente: *lele
    - attrezzatura: *macchina

The key entry may be either a single attribute name or a list of them, not necessarily corresponding to the primary key of the entity. To handle the simplest case of structured values (for example, when a field is backed by a PostgreSQL HSTORE), the key attribute name may be in the form name->slot:

- entity: model.Product
  key: description->en
  data:
    - &cage
      description:
        en: "Roadrunner cage"
        it: "Gabbia per struzzi"

When all (or most of) the instances share the same fields, a more compact representation may be used:

- entity: model.Values
  key:
    - product
    - attribute
  fields: [ product, attribute, value ]
  data:
    - [ *cage, *size, 110cm x 110cm x 120cm ]
    - [ *cage, *weight, 230kg ]

where fields contains a list of field names and data is a sequence of lists, each containing the values of a single instance. The two sintaxes may be mixed though, so you can say:

- entity: model.Person
  key: [ lastname, firstname ]
  fields: [ lastname, firstname, password ]
  data:
    - [ gaifax, lele, "123456" ]
    - [ foobar, john, "abcdef" ]
    - lastname: rossi
      firstname: paolo
      birthdate: 1950-02-03

With the option --save-new-instances newly created instances will be written (actually added) to the given file in YAML format, so that at some point they can be deleted using the option --delete on that file. Ideally

dbloady -u postgresql://localhost/test -s new.yaml fixture.yaml
dbloady -u postgresql://localhost/test -D new.yaml

should remove fixture’s traces from the database, if it contains only new data.