Rails中的交叉引用表
Rails中的交叉引用表
提问于 2018-05-03 08:30:23
我有一个ads表，它与ad_address和ad_copies表有1:n的关系。然后是类别和子类别表，其中类别与子类别表有1:n的关系，子类别表与ads表有1:n的关系。
因此，子类别表有一个名为id_categories的引用字段，ads表有一个引用字段id_subcategories。
ads_address表和ads_copy表都有一个ad_id字段。
现在，我一直忙于将json文件(以前的数据库)中的数据导入到一个新的rails应用程序中。我发现这个前一个数据库的模式包含一个单独的表，其中包含所有引用字段，即id_categories、id_subcategories和ad_id字段。
create_table "rel_anuncio", primary_key: ["id_anuncio", "id_categoria", "id_subcategoria"], force: :cascade, options: "ENGINE=MyISAM DEFAULT CHARSET=utf8" do |t|
t.integer "id_anuncio", null: false
t.integer "id_categoria", null: false
t.integer "id_subcategoria", null: false
t.integer "orden", null: false
end下面是我如何创建广告记录( json文件的表名是西班牙语)：
if row['name'] == "categorias"
row["data"].each do |record|
@cat = Category.create!(
user_id: user.id,
name: record["nombre"]
)
end
elsif row['name'] == "subcategorias"
row["data"].each do |record|
@subcat = Subcategory.create!(
category_id: @cat.id,
name: record["nombre"]
)
end
row["data"].each do |record|
@ad = Ad.create!(
user_id: user.id,
subcategory_id: @subcat.id,
[..]
)
end我为行"NoMethodError: undefined method 'id' for nil:NilClass"获得了一个"subcategory_id: @subcat.id"，因为没有subcategory_id链接到我意识到的广告记录，因为subcategory_id位于不同的表中。
现在，我知道必须有一种方法来交叉引用这些id在散列中，这样您就可以看到哪些id号属于哪个记录。例如，如果您有id_subcategory: 3，那么这必须属于带有id: 4的名为"Wok“的广告记录。
我想种子正确的类别和子类别到我的广告记录在我的rails应用程序。
更一般地，我想知道一些人将如何处理如何导入一个数据库的json文件，这个数据库的模式与您自己的数据库在railsapp中的模式不同。
下面是json文件的示例(每个表的第一行)：
[
{"type":"header","version":"4.7.9","comment":"Export to JSON plugin for PHPMyAdmin"},
{"type":"database","name":"qqx486"},
{"type":"table","name":"anuncios","database":"qqx486","data":
[
{"id":"1","empresa":"Wok Bufet Gran Oriente","tel":"971 315 964","fax_principal":"","movil_principal":"","email_principal":"","web":"","facebook":"","horario_v_principal":"","horario_i_principal":"Abierto mediod\u00eda y noche","direccion_principal":"C\/ Jos\u00e9 Zornoza Bernabeu, 15, L2","poblacion_principal":"EIVISSA","activo":"no","tam_anuncio":"completa","twitter":"","link":"no","general":"no","isla":"ibiza","subtitulo":"","comentario":"","modificacion":"0000-00-00 00:00:00","promo1":"0","promo2":"0","instagram":"","tel2":"","tel3":"","tel4":"","movil2":"","movil3":"","movil4":""},
]
}
,{"type":"table","name":"anuncios_direcciones","database":"qqx486","data":
[
{"id":"157","id_anuncio":"1","direccion":"C\/ Sant Jaume, 114","poblacion":"SANTA EUL\u00c0RIA","telefono":" 971 336 274","fax":"","movil":"","email":"","horario_i":"","horario_v":""},
]
}
,{"type":"table","name":"anuncios_gps_a","database":"qqx486","data":
[
{"id":"1","id_anuncio":"22","lat":"38.9082100","lon":"1.4289690","accuracy":"10"},
]
}
,{"type":"table","name":"anuncios_gps_b","database":"qqx486","data":
[
{"id_anuncio_direcciones":"459","id_anuncio":"1068","lat":"0.0000000","lon":"0.0000000","acc":"0"},
]
}
,{"type":"table","name":"anuncios_textos","database":"qqx486","data":
[
{"id_anuncio":"1","id_idioma":"1","descripcion":""},
]
}
,{"type":"table","name":"caracteristicas","database":"qqx486","data":
[
{"id":"1","nombre":"Jard\u00edn"},
]
}
,{"type":"table","name":"caracteristicas_textos","database":"qqx486","data":
[
{"id_caracteristica":"1","id_idioma":"1","titulo":"Jard\u00edn"},
]
}
,{"type":"table","name":"categorias","database":"qqx486","data":
[
{"id":"1","nombre":"RESTAURANTES Y ALIMENTACI\u00d3N","color":"","activo":"si","bdd":"guias","orden":"1","promoI":"0","promoF":"0","islas":"3"},
]
}
,{"type":"table","name":"categorias_porsi","database":"qqx486","data":
[
{"id":"1","nombre":"RESTAURANTES Y ALIMENTACI\u00d3N","color":"","activo":"si","bdd":"guias","orden":"1","promoI":"0","promoF":"0"},
]
}
,{"type":"table","name":"categorias_textos","database":"qqx486","data":
[
{"id_categoria":"1","id_idioma":"1","titulo":"RESTAURANTES Y ALIMENTACI\u00d3N","clave":""},
]
}
,{"type":"table","name":"enlaces","database":"qqx486","data":
[
{"id":"1","nombre":"Digital Grafic Ibiza","web":"http:\/\/www.bestof.org"}
]
}
,{"type":"table","name":"enlaces_textos","database":"qqx486","data":
[
{"id_enlace":"1","id_idioma":"1","descripcion":"Empresa en Ibiza"},
]
}
,{"type":"table","name":"idiomas","database":"qqx486","data":
[
{"id":"1","nombre":"Espa\u00f1ol","self":"es","color":"F00"},
]
}
,{"type":"table","name":"inmuebles","database":"qqx486","data":
[
{"id":"1","ref":"Roca Llisa","id_inmobiliaria":"91","tipo":"piso","estado":"","zona":"Santa Eulalia","sup_vivienda":"0","sup_parcela":"0","sup_terrazas":"0","plantas":"0","dormitorios":"3","banyos":"2","piscina":"no","parking":"no","entorno":"","precio":"380000","activo":"si"},
]
}
,{"type":"table","name":"inmuebles_textos","database":"qqx486","data":
[
{"id_inmueble":"1","id_idioma":"1","titulo":"Roca Llisa","descripcion":"Apartamento d\u00faplex, cocina, sal\u00f3n\/comedor, 2 terrazas, preciosas vistas al mar, piscina y paddle tenis comunitarios."},
]
}
,{"type":"table","name":"playas","database":"qqx486","data":
[
{"id":"1","nombre":"PLATJA DE TALAMANCA","longitud":"900","orientacion":"SE","google":"https:\/\/www.google.es\/maps\/place\/Cala+Talamanca\/@38.9132677,1.4565971,16z\/data=!4m2!3m1!1s0x1299414743b6e207:0xe628e2f006419c0d","cnauticas":"38\u00b055\u201900.8\u201dN 1\u00b027\u201916.8\u201dE","municipio":"Eivissa","activo":"si","orden":"0"},
]
}
,{"type":"table","name":"playas_textos","database":"qqx486","data":
[
{"id_playa":"1","id_idioma":"1","breve":"Playa de arena fina a pocos minutos a pie de Marina Botafoch y a 1,8 km. del centro de la ciudad de Eivissa.","descripcion":"Se trata de una bah\u00eda cerrada, poco profunda, ideal para el ba\u00f1o sin ning\u00fan peligro y muy bien protegida por los vientos. Gran variedad en restaurantes, bares y chiringuitos, incluso algunos est\u00e1n abiertos todo el a\u00f1o. Existe una pasarela de madera a lo largo de casi toda la playa. Se realizan cursos para iniciarse en deportes n\u00e1uticos como el catamar\u00e1n, kayak y windsurf.","servicios":"Restaurantes y chiringuitos \u2013 Hoteles \u2013 Alquiler de tumbonas y sombrillas \u2013 Deportes acu\u00e1ticos \u2013 Duchas y WC p\u00fablicos \u2013 Acceso minusv\u00e1lidos \u2013 Parking gratis \u2013 Transporte p\u00fablico.","llegar":"En coche, en autob\u00fas de l\u00ednea regular o en una barquita que va del puerto de Eivissa hasta Botafoch, y de ah\u00ed puede ir andando llegando en pocos minutos."},
]
}
,{"type":"table","name":"promo","database":"qqx486","data":
[
{"id":"1","idioma":"1","empresa_id":"943","titulo":"10% Descuento","tituloCR":"8","tituloCG":"8","tituloCB":"8","tituloFS":"20","texto1":"7 horas de fiesta y mucho m\u00e1s","texto1CR":"255","texto1CG":"255","texto1CB":"255","texto1FS":"20","fondo1CR":"255","fondo1CG":"43","fondo1CB":"227","fondo1CA":"90","texto2":"","foto1":"","foto2":"","code":"C\u00f3digo: Isla Blanca","tiempo1":"0000-00-00 00:00:00","tiempo2":"0000-00-00 00:00:00","activo":"2","status":"1","orden":"1"},
]
}
,{"type":"table","name":"rel_anuncio","database":"qqx486","data":
[
{"id_anuncio":"814","id_categoria":"7","id_subcategoria":"81","orden":"37"},
]
}
,{"type":"table","name":"rel_guias","database":"qqx486","data":
[
{"id_anuncio":"7","id_guia":"1"},
]
}
,{"type":"table","name":"rel_inmuebles","database":"qqx486","data":
[
{"id_inmueble":"1","id_caracteristica":"2"},
]
}
,{"type":"table","name":"subcategorias","database":"qqx486","data":
[
{"id":"1","id_categoria":"1","nombre":"Restaurantes","color":"","activo":"si","orden":"1","promoI":"0","promoF":"0","islas":"3"},
]
}
,{"type":"table","name":"subcategorias_porsi","database":"qqx486","data":
[
{"id":"1","id_categoria":"1","nombre":"Restaurantes","color":"","activo":"si","orden":"1","promoI":"0","promoF":"0"},
]
}
,{"type":"table","name":"subcategorias_textos","database":"qqx486","data":
[
{"id_subcategoria":"1","id_idioma":"1","nombre":"Restaurantes","clave":"restaurantes, pizzer\u00edas, los productos de alimentaci\u00f3n, almuerzos, cenas, fiestas, c\u00f3cteles, cocktails, comen, comer, beber, las cocinsa mediterr\u00e1neas, barras, comedores, comiento, sitios para comer, restaurantes especializados en bistecs, el alimento japon\u00e9s, comida japonesa, el alimento espa\u00f1ol, comida espa\u00f1ola, el alimento italiano, comida italiana, parrillas, la cocina francesa, el alimento alem\u00e1n, comida alemana, comidas, licores, mariscos, el alimento asi\u00e1tico, comida asi\u00e1tica, pescados, mariscos, camarones, gambas, tabernas,"},
]
}
,{"type":"table","name":"version","database":"qqx486","data":
[
{"id":"32"}
]
}
]回答 1
Stack Overflow用户
回答已采纳
发布于 2018-05-03 17:09:00
看来Ad & Subcategory有很多种关系。因此，rel_anuncio是建立关系的中间表。
由于json的行与创建记录的方式不同，所以顺序不同。
相反，尝试首先创建Ads，然后在最后创建Categories和Subcategories。
json_ads = parsed_json.find { |table| table['name'] == 'anuncios' }
ads = {}
json_ads['data'].each do |ad|
ads[ad['id']] = Ad.create(
[... ad fields]
)
endCategories也是如此
json_categories = parsed_json.find { |table| table['name'] == 'categorias' }
categories = {}
json_categories['data'].each do |category|
categories[category['id']] = Category.create(
[... category fields]
)
end创建了Subcategories之后，就有了带有Categories的Hash来引用它们：
json_subcategories = json.find { |table| table['name'] == 'rel_anuncio' }
subcategories = {}
json_subcategories['data'].each do |subcategory|
subcategories[subcategory['id']] = Subcategory.create(
category: categories[subcategory['id_categoria'],
[... ad fields]
)
endrel_anuncio信息将取决于您如何实现关系。
希望能帮上忙。
页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/50150406
复制相关文章
相似问题
腾讯云开发者
Copyright © 2013 - 2026 Tencent Cloud. All Rights Reserved. 腾讯云 版权所有
深圳市腾讯计算机系统有限公司 ICP备案/许可证号：粤B2-20090059 
粤公网安备44030502008569号
腾讯云计算（北京）有限责任公司 京ICP证150476号 | 京ICP备11018762号