Add unique constraint to collections_series table.

Fix #163

No functional changes.

Author: cssru

src/main/java/ru/mystamps/web/entity/Collection.java

@@ -28,6 +28,7 @@
 import javax.persistence.ManyToMany;
 import javax.persistence.OneToOne;
 import javax.persistence.Table;
+import javax.persistence.UniqueConstraint;
 
 import lombok.Getter;
 import lombok.Setter;
@@ -51,7 +52,14 @@ public class Collection {
 	private User owner;
 
 	@ManyToMany
-	@JoinTable(joinColumns = @JoinColumn(name = "collection_id"))
+	@JoinTable(
+		joinColumns = @JoinColumn(name = "collection_id"), 
+		inverseJoinColumns = @JoinColumn(name = "series_id"),
+		uniqueConstraints = @UniqueConstraint(
+			name = "uc_collections_series_collection_id_series_id",
+			columnNames = { "collection_id", "series_id" }
+		)
+	)
 	private Set<Series> series;
 
 	@Column(length = SLUG_LENGTH, nullable = false)

src/main/resources/liquibase/version/0.4.xml

@@ -11,5 +11,6 @@
 	<include file="0.4/2015-10-14--http-method.xml" relativeToChangelogFile="true" />
 	<include file="0.4/2015-11-13--nullable_columns.xml" relativeToChangelogFile="true" />
 	<include file="0.4/2016-01-02--non_unique_catalog_numbers.xml" relativeToChangelogFile="true" />
+	<include file="0.4/2016-01-04--unique_series_in_collection.xml" relativeToChangelogFile="true" />
 
 </databaseChangeLog>

src/main/resources/liquibase/version/0.4/2016-01-04--unique_series_in_collection.xml

@@ -0,0 +1,17 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<databaseChangeLog
+		xmlns="http://www.liquibase.org/xml/ns/dbchangelog"
+		xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+		xsi:schemaLocation="http://www.liquibase.org/xml/ns/dbchangelog
+		http://www.liquibase.org/xml/ns/dbchangelog/dbchangelog-3.0.xsd">
+
+	<changeSet id="add-unique-constraint-to-collections_series-table" author="cssru" context="scheme">
+
+		<addUniqueConstraint
+			tableName="collections_series"
+			columnNames="collection_id, series_id"
+			constraintName="uc_collections_series_collection_id_series_id"/>
+
+	</changeSet>
+
+</databaseChangeLog>