jpa example

integration/spring_jpa/.gitignore

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+HELP.md
+target/
+!.mvn/wrapper/maven-wrapper.jar
+!**/src/main/**/target/
+!**/src/test/**/target/
+
+### STS ###
+.apt_generated
+.classpath
+.factorypath
+.project
+.settings
+.springBeans
+.sts4-cache
+
+### IntelliJ IDEA ###
+.idea
+*.iws
+*.iml
+*.ipr
+
+### NetBeans ###
+/nbproject/private/
+/nbbuild/
+/dist/
+/nbdist/
+/.nb-gradle/
+build/
+!**/src/main/**/build/
+!**/src/test/**/build/
+
+### VS Code ###
+.vscode/

integration/spring_jpa/.mvn/wrapper/maven-wrapper.properties

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+distributionUrl=https://repo.maven.apache.org/maven2/org/apache/maven/apache-maven/3.8.6/apache-maven-3.8.6-bin.zip
+wrapperUrl=https://repo.maven.apache.org/maven2/org/apache/maven/wrapper/maven-wrapper/3.1.0/maven-wrapper-3.1.0.jar

integration/spring_jpa/README.adoc

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+= JPA Example
+
+Examples prepared to explain the below concepts.
+
+1. Use Lazy loading
+2. Usage of java.time.localdate.
+3. Enum usage with converter
+
+
+=== Lazy loading
+
+Always advised to use lazy loading. Lazy loading fetches data only when it is really required. This example uses FetchType Lazy, the invited guests will be loaded only on demand.
+
+A `SELECT` query applied for fetching booking or bookings will not fetch any invited guests. The below statement fetches all guests for a particular booking. It executes a `SELECT` query with booking id as arguement.
+ `BookingEntity.getInvitedGuests()`
+
+
+=== Enum
+
+Using Converter annotation convert an entity attribute to a database value and vice versa. In this example, enum defined as BOOKED("B"), and NOTBOOKED("N") and CANCELED ("C"). This helps to make sure the code is not broken by refactorings.
+
+The other two ways to deal with enums are by their `Ordinal` or by `name`. `Ordinal` may not be a good choice, if someone changes the places of the items in enum, wrong integer value may be stored.
+
+=== LocalDateTime
+
+java.time.LocalDateTime used instead of java.util.date, major benefits are:
+
+* LocalDateTime API has its own format/parse methods.
+* Addition/subtraction operation are easier (minusMinutes,plusDays etc.)
+
+