31 lines
1.3 KiB
Markdown
31 lines
1.3 KiB
Markdown
# Spring Data MongoDB - Query-by-Example (QBE) example
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This project contains samples of Query-by-Example of Spring Data MongoDB.
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## Support for Query-by-Example
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Query by Example (QBE) is a user-friendly querying technique with a simple interface. It allows dynamic query creation and does not require to write queries containing field names. In fact, Query by Example does not require to write queries using JPA-QL at all.
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An `Example` takes a data object (usually the entity object or a subtype of it) and a specification how to match properties. You can use Query by Example with `MongoOperations` and Repositories.
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```java
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public interface PersonRepository extends CrudRepository<Person, String>, QueryByExampleExecutor {
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}
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```
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```java
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Example<Person> example = Example.of(new Person("Jon", "Snow"));
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repo.findAll(example);
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ExampleMatcher matcher = ExampleMatcher.matching().
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.withMatcher("firstname", endsWith())
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.withMatcher("lastname", startsWith().ignoreCase());
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Example<Person> example = Example.of(new Person("Jon", "Snow"), matcher);
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repo.count(example);
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```
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This example contains two test classes to illustrate Query-by-Example with `MongoOperations` in `MongoOperationsIntegrationTests` and the usage with a Repository in `UserRepositoryIntegrationTests`.
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