#3664 Fix / support for extra JoinColumns on ManyToOne (#3668)

* #3664 Fix / support for extra JoinColumns on ManyToOne

Allows for extra JoinColumns on ManyToOne. The extra JoinColumn(s) are
expected to be useful for the case of table partitioning where the extra
join column is used to partition the table. In the test case, the partition
column would be the org_id column and common to both tables (same partition key).

* #3664 Fix / support for extra JoinColumns on ManyToOne

Allows for extra JoinColumns on ManyToOne. The extra JoinColumn(s) are
expected to be useful for the case of table partitioning where the extra
join column is used to partition the table. In the test case, the partition
column would be the org_id column and common to both tables (same partition key).

* #3664 Extend test

* #3664 Tidy up test

Author: rbygrave

ebean-core/src/main/java/io/ebeaninternal/server/deploy/BeanPropertyAssoc.java

@@ -436,14 +436,15 @@ ImportedId createImportedId(BeanPropertyAssoc<?> owner, BeanDescriptor<?> target
     }
     TableJoinColumn[] cols = join.columns();
     if (!idProp.isEmbedded()) {
-      // simple single scalar id
-      if (cols.length != 1) {
-        CoreLog.log.log(ERROR, "No Imported Id column for {0} in table {1}", idProp, join.getTable());
-        return null;
-      } else {
-        BeanProperty[] idProps = {idProp};
-        return createImportedScalar(owner, cols[0], idProps, others);
+      // simple single scalar id, match on the foreign column, allow extra TableJoinColumn for #3664
+      String matchColumn = idProp.dbColumn();
+      for (TableJoinColumn col : cols) {
+        if (matchColumn.equals(col.getForeignDbColumn())) {
+          return createImportedScalar(owner, col, new BeanProperty[]{idProp}, others);
+        }
       }
+      CoreLog.log.log(ERROR, "No Imported Id column for {0} in table {1}", idProp, join.getTable());
+      return null;
     } else {
       // embedded id
       BeanPropertyAssocOne<?> embProp = (BeanPropertyAssocOne<?>) idProp;

ebean-core/src/main/java/io/ebeaninternal/server/deploy/BeanPropertyAssocOne.java

@@ -128,16 +128,6 @@ private void initialiseAssocOne(String embeddedPrefix) {
           throw new PersistenceException("Cannot find imported id for " + fullName() + " from " + targetDescriptor
           + ". If using native-image, possibly missing reflect-config for the Id property.");
         }
-        if (importedId.isScalar()) {
-          // limit JoinColumn mapping to the @Id / primary key
-          TableJoinColumn[] columns = tableJoin.columns();
-          String foreignJoinColumn = columns[0].getForeignDbColumn();
-          String foreignIdColumn = targetDescriptor.idProperty().dbColumn();
-          if (!foreignJoinColumn.equalsIgnoreCase(foreignIdColumn)) {
-            throw new PersistenceException("Mapping limitation - @JoinColumn on " + fullName() + " needs to map to a primary key as per Issue #529 "
-              + " - joining to " + foreignJoinColumn + " and not " + foreignIdColumn);
-          }
-        }
       } else {
         exportedProperties = createExported();
         String delStmt = "delete from " + targetDescriptor.baseTable() + " where ";

ebean-ddl-generator/src/main/java/io/ebeaninternal/dbmigration/model/build/ModelBuildPropertyVisitor.java

@@ -195,7 +195,7 @@ public void visitOneImported(BeanPropertyAssocOne<?> p) {
       String dbCol = column.getLocalDbColumn();
       BeanProperty importedProperty = p.findMatchImport(dbCol);
       if (importedProperty == null) {
-        throw new RuntimeException("Imported BeanProperty not found?");
+        continue;
       }
       String columnDefn = ctx.getColumnDefn(importedProperty, true);
       String refColumn = importedProperty.dbColumn();

ebean-test/src/test/java/org/tests/model/m2o/MTJOrder.java

@@ -0,0 +1,45 @@
+package org.tests.model.m2o;
+
+import jakarta.persistence.Column;
+import jakarta.persistence.Entity;
+import jakarta.persistence.Id;
+
+@Entity
+public class MTJOrder {
+
+  @Id
+  private long id;
+
+  @Column(name = "org_id")
+  private long orgId;
+
+  @Column
+  private String other;
+
+  public Long id() {
+    return id;
+  }
+
+  public MTJOrder setId(Long id) {
+    this.id = id;
+    return this;
+  }
+
+  public Long orgId() {
+    return orgId;
+  }
+
+  public MTJOrder setOrgId(Long orgId) {
+    this.orgId = orgId;
+    return this;
+  }
+
+  public String other() {
+    return other;
+  }
+
+  public MTJOrder setOther(String other) {
+    this.other = other;
+    return this;
+  }
+}

ebean-test/src/test/java/org/tests/model/m2o/MTJTrans.java

@@ -0,0 +1,47 @@
+package org.tests.model.m2o;
+
+import jakarta.persistence.*;
+
+@Entity
+public class MTJTrans {
+
+  @Id
+  private long id;
+
+  @Column(name = "org_id")
+  private long orgId;
+
+  @ManyToOne
+  @JoinColumns({
+    @JoinColumn(name = "org_id", referencedColumnName = "org_id"), // extra join column, not strictly needed
+    @JoinColumn(name = "order_id", referencedColumnName = "id")
+  })
+  private MTJOrder order;
+
+  public Long id() {
+    return id;
+  }
+
+  public MTJTrans setId(Long id) {
+    this.id = id;
+    return this;
+  }
+
+  public Long orgId() {
+    return orgId;
+  }
+
+  public MTJTrans setOrgId(Long orgId) {
+    this.orgId = orgId;
+    return this;
+  }
+
+  public MTJOrder order() {
+    return order;
+  }
+
+  public MTJTrans setOrder(MTJOrder order) {
+    this.order = order;
+    return this;
+  }
+}

ebean-test/src/test/java/org/tests/model/m2o/TestMTJoinColumns.java

@@ -0,0 +1,48 @@
+package org.tests.model.m2o;
+
+import io.ebean.DB;
+import io.ebean.test.LoggedSql;
+import org.junit.jupiter.api.Test;
+
+import java.util.List;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+class TestMTJoinColumns {
+
+  @Test
+  void test() {
+    MTJTrans parent = new MTJTrans();
+    parent.setOrgId(51L);
+
+    DB.save(parent);
+
+    MTJTrans found = DB.find(MTJTrans.class)
+      .setId(parent.id())
+      .fetch("order")
+      .findOne();
+
+    assertThat(found.order()).isNull();
+
+    var order = new MTJOrder()
+      .setOrgId(51L)
+      .setOther("some");
+    DB.save(order);
+    found.setOrder(order);
+    DB.save(found);
+
+    LoggedSql.start();
+    MTJTrans found2 = DB.find(MTJTrans.class)
+      .setId(parent.id())
+      .fetch("order")
+      .findOne();
+
+    assertThat(found2.order()).isNotNull();
+    assertThat(found2.order().id()).isEqualTo(order.id());
+    assertThat(found2.order().other()).isEqualTo("some");
+
+    List<String> sql = LoggedSql.stop();
+    assertThat(sql).hasSize(1);
+    assertThat(sql.get(0)).contains("from mtjtrans t0 left join mtjorder t1 on t1.org_id = t0.org_id and t1.id = t0.order_id where t0.id = ?");
+  }
+}