NEW: Ebean.checkUniqueness - you can check a bean, if save would work (#1303)

src/main/java/io/ebean/Ebean.java

@@ -3,11 +3,13 @@ package io.ebean;
 import io.ebean.annotation.TxIsolation;
 import io.ebean.cache.ServerCacheManager;
 import io.ebean.config.ServerConfig;
+import io.ebean.plugin.Property;
 import io.ebean.text.csv.CsvReader;
 import io.ebean.text.json.JsonContext;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
+import javax.annotation.Nonnull;
 import javax.annotation.Nullable;
 import javax.persistence.OptimisticLockException;
 import javax.persistence.PersistenceException;
@@ -15,6 +17,7 @@ import java.util.Collection;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
+import java.util.Set;
 import java.util.concurrent.Callable;
 import java.util.concurrent.ConcurrentHashMap;
 
@@ -116,7 +119,7 @@ public final class Ebean {
   static {
     EbeanVersion.getVersion(); // initalizes the version class and logs the version.
   }
- 
+
   /**
    * Manages creation and cache of EbeanServers.
    */
@@ -641,6 +644,30 @@ public final class Ebean {
     return serverMgr.getDefaultServer().saveAll(beans);
   }
 
+  /**
+   * This method checks the uniqueness of a bean. I.e. if the save will work. It will return the
+   * properties that violates an unique / primary key. This may be done in an UI save action to
+   * validate if the user has entered correct values.
+   *
+   * Note: This method queries the DB for uniqueness of all indices, so do not use it in a batch update.
+   *
+   * TODO: it checks only the root bean!
+   * @param bean
+   * @return a set of Properties if constraint validation was detected or empty list.
+   */
+  @Nonnull
+  public static Set<Property> checkUniqueness(Object bean) {
+    return serverMgr.getDefaultServer().checkUniqueness(bean);
+  }
+
+  /**
+   * Same as {@link #checkUniqueness(Object)}. but with given transaction.
+   */
+  @Nonnull
+  public static Set<Property> checkUniqueness(Object bean, Transaction transaction) {
+    return serverMgr.getDefaultServer().checkUniqueness(bean, transaction);
+  }
+
   /**
    * Delete the bean.
    * <p>

src/main/java/io/ebean/EbeanServer.java

@@ -4,6 +4,7 @@ import io.ebean.annotation.TxIsolation;
 import io.ebean.cache.ServerCacheManager;
 import io.ebean.config.ServerConfig;
 import io.ebean.meta.MetaInfoManager;
+import io.ebean.plugin.Property;
 import io.ebean.plugin.SpiServer;
 import io.ebean.text.csv.CsvReader;
 import io.ebean.text.json.JsonContext;
@@ -1461,6 +1462,26 @@ public interface EbeanServer {
    */
   int saveAll(Collection<?> beans, Transaction transaction) throws OptimisticLockException;
 
+  /**
+   * This method checks the uniqueness of a bean. I.e. if the save will work. It will return the
+   * properties that violates an unique / primary key. This may be done in an UI save action to 
+   * validate if the user has entered correct values.
+   * 
+   * Note: This method queries the DB for uniqueness of all indices, so do not use it in a batch update.
+   * 
+   * TODO: it checks only the root bean!
+   * @param bean
+   * @return a set of Properties if constraint validation was detected or empty list.
+   */
+  @Nonnull
+  Set<Property> checkUniqueness(Object bean);
+  
+  /**
+   * Same as {@link #checkUniqueness(Object)}. but with given transaction.
+   */
+  @Nonnull
+  Set<Property> checkUniqueness(Object bean, Transaction transaction);
+
   /**
    * Marks the entity bean as dirty.
    * <p>

src/main/java/io/ebeaninternal/server/core/DefaultServer.java

@@ -6,6 +6,7 @@ import io.ebean.BeanState;
 import io.ebean.CallableSql;
 import io.ebean.DocumentStore;
 import io.ebean.ExpressionFactory;
+import io.ebean.ExpressionList;
 import io.ebean.Filter;
 import io.ebean.FutureIds;
 import io.ebean.FutureList;
@@ -49,6 +50,7 @@ import io.ebean.meta.MetaInfoManager;
 import io.ebean.meta.MetaTimedMetric;
 import io.ebean.plugin.BeanType;
 import io.ebean.plugin.Plugin;
+import io.ebean.plugin.Property;
 import io.ebean.plugin.SpiServer;
 import io.ebean.text.csv.CsvReader;
 import io.ebean.text.json.JsonContext;
@@ -104,7 +106,10 @@ import javax.persistence.OptimisticLockException;
 import javax.persistence.PersistenceException;
 import javax.sql.DataSource;
 import java.util.Collection;
+import java.util.Collections;
+import java.util.HashSet;
 import java.util.Iterator;
+import java.util.LinkedHashSet;
 import java.util.List;
 import java.util.Map;
 import java.util.Optional;
@@ -2109,4 +2114,78 @@ public final class DefaultServer implements SpiServer, SpiEbeanServer {
   public List<MetaTimedMetric> collectTransactionStatistics(boolean reset) {
     return transactionManager.collectTransactionStatistics(reset);
   }
+
+  @Override
+  public Set<Property> checkUniqueness(Object bean) {
+    return checkUniqueness(bean, null);
+  }
+
+  @Override
+  public Set<Property> checkUniqueness(Object bean, Transaction transaction) {
+
+    EntityBean entityBean = checkEntityBean(bean);
+    BeanDescriptor<?> beanDesc = getBeanDescriptor(entityBean.getClass());
+
+    BeanProperty idProperty = beanDesc.getIdProperty();
+    // if the ID of the Property is null we are unable to check uniqueness
+    if (idProperty == null) {
+      return Collections.emptySet();
+    }
+
+    Object id = idProperty.getVal(entityBean);
+    if (entityBean._ebean_intercept().isNew() && id != null) {
+      // Primary Key is changeable only on new models - so skip check if we are not
+      // new.
+      Query<?> query = new DefaultOrmQuery<>(beanDesc, this, expressionFactory);
+      query.setId(id);
+      if (findCount(query, transaction) > 0) {
+        Set<Property> ret = new HashSet<>();
+        ret.add(idProperty);
+        return ret;
+      }
+    }
+
+    for (BeanProperty[] props : beanDesc.getUniqueProps()) {
+      Set<Property> ret = checkUniqueness(entityBean, beanDesc, props, transaction);
+      if (ret != null) {
+        return ret;
+      }
+    }
+    return Collections.emptySet();
+  }
+
+
+  /**
+   * Returns a set of properties if saving the bean will violate the unique constraints
+   * (definded by given properties).
+   */
+  private Set<Property> checkUniqueness(EntityBean entityBean, BeanDescriptor<?> beanDesc, BeanProperty[] props,
+      Transaction transaction) {
+    BeanProperty idProperty = beanDesc.getIdProperty();
+    Query<?> query = new DefaultOrmQuery<>(beanDesc, this, expressionFactory);
+    ExpressionList<?> exprList = query.where();
+
+    if (!entityBean._ebean_intercept().isNew()) {
+      // if model is not new, exclude ourself.
+      exprList.ne(idProperty.getName(), idProperty.getVal(entityBean));
+    }
+
+    for (Property prop : props) {
+      Object value = prop.getVal(entityBean);
+      if (value == null) {
+        return null;
+      }
+      exprList.eq(prop.getName(), value);
+    }
+
+    if (findCount(query, transaction) > 0) {
+      Set<Property> ret = new LinkedHashSet<>();
+      for (Property prop : props) {
+        ret.add(prop);
+      }
+      return ret;
+    }
+    return null;
+  }
+
 }

src/main/java/io/ebeaninternal/server/deploy/BeanDescriptor.java

@@ -350,6 +350,7 @@ public class BeanDescriptor<T> implements BeanType<T> {
   protected final BeanProperty[] propertiesIndex;
   private final BeanProperty[] propertiesGenInsert;
   private final BeanProperty[] propertiesGenUpdate;
+  private final List<BeanProperty[]> propertiesUnique = new ArrayList<>();
 
   /**
    * The bean class name or the table name for MapBeans.
@@ -769,9 +770,43 @@ public class BeanDescriptor<T> implements BeanType<T> {
    * Perform last initialisation for the descriptor.
    */
   public void initLast() {
+
+    for (BeanProperty prop : propertiesNonTransient) {
+      if (prop.isUnique()) {
+        propertiesUnique.add(new BeanProperty[] { prop });
+      }
+    }
+    // convert unique columns to properties
+    if (indexDefinitions != null) {
+      for (IndexDefinition indexDef : indexDefinitions) {
+        if (indexDef.isUnique()) {
+          addUniqueColumns(indexDef);
+        }
+      }
+    }
     docStoreEmbeddedInvalidation = docStoreAdapter.hasEmbeddedInvalidation();
   }
 
+  private void addUniqueColumns(IndexDefinition indexDef) {
+    String[] cols = indexDef.getColumns();
+    BeanProperty[] props = new BeanProperty[cols.length];
+    for (int i = 0; i < cols.length; i++) {
+      String propName = findBeanPath("", cols[i]);
+      if (propName == null) {
+        return;
+      }
+      props[i] = findBeanProperty(propName);
+    }
+    if (props.length == 1) {
+      for (BeanProperty[] inserted : propertiesUnique) {
+        if (inserted.length == 1 && inserted[0].equals(props[0])) {
+          return; // do not insert duplicates
+        }
+      }
+    }
+    propertiesUnique.add(props);
+  }
+
   /**
    * Initialise the document mapping.
    */
@@ -3220,4 +3255,7 @@ public class BeanDescriptor<T> implements BeanType<T> {
     return jsonHelp.jsonReadObject(jsonRead, path);
   }
 
+  public List<BeanProperty[]> getUniqueProps() {
+    return propertiesUnique;
+  }
 }