Um dos principais bancos de dados NoSQL, o MongoDB é conhecido por seu desempenho rápido, esquema versátil, escalabilidade e excelentes recursos para indexação. Vejamos alguns contextos antes de entrarmos em alguns detalhes. A pesquisa de texto completo é um recurso essencial quando falamos em encontrar conteúdo na internet. Uma pesquisa no google é o melhor exemplo disso quando vemos o conteúdo usando as frases ou palavras-chave. Neste artigo, aprenderemos sobre os recursos de pesquisa de texto completo no MongoDB com base no índice de texto.
Criar um banco de dados de amostra
Antes de começarmos, criaremos um banco de dados de exemplo que será usado durante o tutorial.
Criaremos um banco de dados com o nome myDB e crie uma coleção com o nome livros . Para isso, a declaração seria a seguinte.
> use myDB
> db.createCollection("books")
>Vamos inserir alguns documentos usando a seguinte instrução.
> db.books.insert([
{
"title": "Eloquent JavaScript, Second Edition",
"subtitle": "A Modern Introduction to Programming",
"author": "Marijn Haverbeke",
"publisher": "No Starch Press",
"description": "JavaScript lies at the heart of almost every modern web application, from social apps to the newest browser-based games. Though simple for beginners to pick up and play with, JavaScript is a flexible, complex language that you can use to build full-scale applications."
},
{
"title": "Learning JavaScript Design Patterns",
"subtitle": "A JavaScript and jQuery Developer's Guide",
"author": "Addy Osmani",
"publisher": "O'Reilly Media",
"description": "With Learning JavaScript Design Patterns, you'll learn how to write beautiful, structured, and maintainable JavaScript by applying classical and modern design patterns to the language. If you want to keep your code efficient, more manageable, and up-to-date with the latest best practices, this book is for you."
},
{
"title": "Speaking JavaScript",
"subtitle": "An In-Depth Guide for Programmers",
"author": "Axel Rauschmayer",
"publisher": "O'Reilly Media",
"description": "Like it or not, JavaScript is everywhere these days, from browser to server to mobile and now you, too, need to learn the language or dive deeper than you have. This concise book guides you into and through JavaScript, written by a veteran programmer who once found himself in the same position."
},
{
"title": "Programming JavaScript Applications",
"subtitle": "Robust Web Architecture with Node, HTML5, and Modern JS Libraries",
"author": "Eric Elliott",
"publisher": "O'Reilly Media",
"description": "Take advantage of JavaScript's power to build robust web-scale or enterprise applications that are easy to extend and maintain. By applying the design patterns outlined in this practical book, experienced JavaScript developers will learn how to write flexible and resilient code that's easier-yes, easier-to work with as your codebase grows."
},
{
"title": "Understanding ECMAScript 6",
"subtitle": "The Definitive Guide for JavaScript Developers",
"author": "Nicholas C. Zakas",
"publisher": "No Starch Press",
"description": "ECMAScript 6 represents the biggest update to the core of JavaScript in the history of the language. In Understanding ECMAScript 6, expert developer Nicholas C. Zakas provides a complete guide to the object types, syntax, and other exciting changes that ECMAScript 6 brings to JavaScript."
}
])Criando um índice de texto
Precisamos criar um índice de texto nos campos para realizar a pesquisa de texto. Podemos criar isso em um ou vários campos. A instrução a seguir criará um índice de texto em um único campo.
>db.books.createIndex({"description":"text"})Criaremos um índice de texto na descrição e legenda campos para este tutorial. Podemos criar apenas um índice de texto por coleção no MongoDB. Então, vamos criar um índice de texto composto usando a seguinte instrução.
>db.books.createIndex({"subtitle":"text","description":"text"})$search
Agora vamos tentar pesquisar documentos que tenham as palavras-chave 'ECMAScript' na descrição e legenda Campos. Para isso, podemos usar a declaração abaixo.
db.books.find({$text: {$search: "ECMAScript"}})Exemplo
>db.books.find({$text: {$search: "ECMAScript"}},{ subtitle: 1, description: 1 })
{
"_id" : ObjectId("602b09cb3cb6144ada1c62fe"),
"subtitle" : "The Definitive Guide for JavaScript Developers",
"description" : "ECMAScript 6 represents the biggest update to the core of JavaScript in the history of the language. In Understanding ECMAScript 6, expert developer Nicholas C. Zakas provides a complete guide to the object types, syntax, and other exciting changes that ECMAScript 6 brings to JavaScript."
}
>Frases
Você pode pesquisar frases usando o índice de texto. Por padrão, a pesquisa de texto realiza uma pesquisa OR para todas as palavras da frase. Se você quiser pesquisar 'padrões de design modernos', ele procurará documentos com as palavras-chave moderno, design ou padrões.
Exemplo
>db.books.find({$text: {$search: "modern design patterns"}},{ subtitle: 1, description: 1 })
{
"_id" : ObjectId("602b098f3cb6144ada1c2ea1"),
"subtitle" : "A JavaScript and jQuery Developer's Guide",
"description" : "With Learning JavaScript Design Patterns, you'll learn how to write beautiful, structured, and maintainable JavaScript by applying classical and modern design patterns to the language. If you want to keep your code efficient, more manageable, and up-to-date with the latest best practices, this book is for you."
},
{
"_id" : ObjectId("602b09b93cb6144ada1c4bca"),
"subtitle" : "Robust Web Architecture with Node, HTML5, and Modern JS Libraries",
"description" : "Take advantage of JavaScript's power to build robust web-scale or enterprise applications that are easy to extend and maintain. By applying the design patterns outlined in this practical book, experienced JavaScript developers will learn how to write flexible and resilient code that's easier-yes, easier-to work with as your code base grows.",
},
{
"_id" : ObjectId("602b095c3cb6144ada1c1028"),
"subtitle" : "A Modern Introduction to Programming",
"description" : "JavaScript lies at the heart of almost every modern web application, from social apps to the newest browser-based games. Though simple for beginners to pick up and play with, JavaScript is a flexible, complex language that you can use to build full-scale applications."
}
>Se você deseja pesquisar frases exatas como documentos com 'padrões de design modernos' juntos, você pode fazer isso especificando aspas duplas no texto de pesquisa.
Exemplo
>db.books.find({$text: {$search: "\"modern design patterns\""}},{ subtitle: 1, description: 1 })
{
"_id" : ObjectId("602b098f3cb6144ada1c2ea1"),
"subtitle" : "A JavaScript and jQuery Developer's Guide",
"description" : "With Learning JavaScript Design Patterns, you'll learn how to write beautiful, structured, and maintainable JavaScript by applying classical and modern design patterns to the language. If you want to keep your code efficient, more manageable, and up-to-date with the latest best practices, this book is for you."
}Negações
Se você deseja excluir os documentos que contêm uma palavra específica, pode usar uma pesquisa de negação. Por exemplo, se você for pesquisar todos os documentos com 'JavaScript', mas não com 'HTML5' ou 'ECMAScript', você pode pesquisar conforme o exemplo abaixo.
Exemplo
>db.books.find({$text: {$search: "JavaScript -HTML5 -ECMAScript"}},{ subtitle: 1, description: 1 })
{
"_id" : ObjectId("602b098f3cb6144ada1c2ea1"),
"subtitle" : "A JavaScript and jQuery Developer's Guide",
"description" : "With Learning JavaScript Design Patterns, you'll learn how to write beautiful, structured, and maintainable JavaScript by applying classical and modern design patterns to the language. If you want to keep your code efficient, more manageable, and up-to-date with the latest best practices, this book is for you."
},
{
"_id" : ObjectId("602b09a83cb6144ada1c4973"),
"subtitle" : "An In-Depth Guide for Programmers",
"description" : "Like it or not, JavaScript is everywhere these days, from browser to server to mobile and now you, too, need to learn the language or dive deeper than you have. This concise book guides you into and through JavaScript, written by a veteran programmer who once found himself in the same position."
},
{
"_id" : ObjectId("602b095c3cb6144ada1c1028"),
"subtitle" : "A Modern Introduction to Programming",
"description" : "JavaScript lies at the heart of almost every modern web application, from social apps to the newest browser-based games. Though simple for beginners to pick up and play with, JavaScript is a flexible, complex language that you can use to build full-scale applications."
}Pontuação da pesquisa de texto
A pesquisa de texto fornece uma pontuação para cada documento que representa a relevância do documento com a consulta de pesquisa. Essa pontuação pode ser usada para classificar todos os registros retornados no resultado da pesquisa. Uma pontuação mais alta indicará uma correspondência mais relevante.
Exemplo
>db.books.find({$text: {$search: "JavaScript "}},{score: {$meta: "textScore"}, subtitle: 1, description: 1 }).sort({score:{$meta:"textScore"}})
{
"_id" : ObjectId("602b098f3cb6144ada1c2ea1"),
"subtitle" : "A JavaScript and jQuery Developer's Guide",
"description" : "With Learning JavaScript Design Patterns, you'll learn how to write beautiful, structured, and maintainable JavaScript by applying classical and modern design patterns to the language. If you want to keep your code efficient, more manageable, and up-to-date with the latest best practices, this book is for you.",
"score" : 1.43269230769231
},
{
"_id" : ObjectId("602b09cb3cb6144ada1c62fe"),
"subtitle" : "The Definitive Guide for JavaScript Developers",
"description" : "ECMAScript 6 represents the biggest update to the core of JavaScript in the history of the language. In Understanding ECMAScript 6, expert developer Nicholas C. Zakas provides a complete guide to the object types, syntax, and other exciting changes that ECMAScript 6 brings to JavaScript.",
"score" : 1.42672413793103
},
{
"_id" : ObjectId("602b09a83cb6144ada1c4973"),
"subtitle" : "An In-Depth Guide for Programmers",
"description" : "Like it or not, JavaScript is everywhere these days, from browser to server to mobile and now you, too, need to learn the language or dive deeper than you have. This concise book guides you into and through JavaScript, written by a veteran programmer who once found himself in the same position.",
"score" : 0.818181818181818
},
{
"_id" : ObjectId("602b095c3cb6144ada1c1028"),
"subtitle" : "A Modern Introduction to Programming",
"description" : "JavaScript lies at the heart of almost every modern web application, from social apps to the newest browser-based games. Though simple for beginners to pick up and play with, JavaScript is a flexible, complex language that you can use to build full-scale applications.",
"score" : 0.801724137931034
},
{
"_id" : ObjectId("602b09b93cb6144ada1c4bca"),
"subtitle" : "Robust Web Architecture with Node, HTML5, and Modern JS Libraries",
"description" : "Take advantage of JavaScript's power to build robust web-scale or enterprise applications that are easy to extend and maintain. By applying the design patterns outlined in this practical book, experienced JavaScript developers will learn how to write flexible and resilient code that's easier-yes, easier-to work with as your codebase grows.",
"score" : 0.792857142857143
}Parar palavras
O operador $text filtra as palavras de parada específicas do idioma, como a, an, the e em inglês. A pesquisa abaixo não retornará nenhum documento no resultado.
Exemplo
>db.books.find({$text: {$search: "is"}},{subtitle: 1, description: 1 })
Fetched 0 record(s)Palavras derivadas
O operador $text corresponde à palavra derivada completa. Portanto, se algum campo do documento contiver a palavra aprender ou aprender, uma pesquisa pelo termo aprender ou aprender resultará no mesmo.
Exemplo
>db.books.find({$text: {$search: " learn"}},{subtitle: 1, description: 1 }) or >db.books.find({$text: {$search: " learning"}},{subtitle: 1, description: 1 })
{
"_id" : ObjectId("602b098f3cb6144ada1c2ea1"),
"subtitle" : "A JavaScript and jQuery Developer's Guide",
"description" : "With Learning JavaScript Design Patterns, you'll learn how to write beautiful, structured, and maintainable JavaScript by applying classical and modern design patterns to the language. If you want to keep your code efficient, more manageable, and up-to-date with the latest best practices, this book is for you."
},
{
"_id" : ObjectId("602b09a83cb6144ada1c4973"),
"subtitle" : "An In-Depth Guide for Programmers",
"description" : "Like it or not, JavaScript is everywhere these days, from browser to server to mobile and now you, too, need to learn the language or dive deeper than you have. This concise book guides you into and through JavaScript, written by a veteran programmer who once found himself in the same position."
},
{
"_id" : ObjectId("602b09b93cb6144ada1c4bca"),
"subtitle" : "Robust Web Architecture with Node, HTML5, and Modern JS Libraries",
"description" : "Take advantage of JavaScript's power to build robust web-scale or enterprise applications that are easy to extend and maintain. By applying the design patterns outlined in this practical book, experienced JavaScript developers will learn how to write flexible and resilient code that's easier-yes, easier-to work with as your codebase grows."
}Conclusão
Espero que você tenha aprendido algo novo hoje. Aqui está um artigo interessante sobre o Self-Hosted MongoDB. Também convido você a experimentar coisas por conta própria e compartilhar sua experiência na seção de comentários. Além disso, se você enfrentar algum problema com qualquer uma das definições acima, sinta-se à vontade para me perguntar na seção de comentários abaixo.
