Spring JPA存储库通用查找与Dandelion DatatableCriterias [英] Spring JPA Repositories Generic FIND WITH Dandelion DatatableCriterias

问题描述

我找到了关于如何实现ajax服务器端处理的示例。

$ b

  @RequestMapping（value =/ persons）
 public @ResponseBody 
 DatatablesResponse< Person> findAllForDataTablesFullSpring（@DatatablesParams DatatablesCriterias标准）{
 DataSet< Person> dataSet = personService.findPersonsWithDatatablesCriterias（criterias）; 
 return DatatablesResponse.build（dataSet，criterias）; 
} 
  

在服务层上

  public DataSet< Person> findPersonsWithDatatablesCriterias（DatatablesCriterias标准）{
 
 List< Person> persons = personRepository.findPersonWithDatatablesCriterias（criterias）; 
 Long count = personRepository.getTotalCount（）; 
 Long countFiltered = personRepository.getFilteredCount（criterias）; 
 
返回新的DataSet< Person>（persons，count，countFiltered）; 
 
  

在数据访问层上

  @Override 
 public List< Person> findPersonWithDatatablesCriterias（DatatablesCriterias标准）{
 
 StringBuilder queryBuilder = new StringBuilder（SELECT p FROM Person p）; 
 $ b / ** 
 *步骤1：全局和个别列过滤
 * / 
 queryBuilder.append（PersonRepositoryUtils.getFilterQuery（criterias））; 
 $ b $ ** 
 *步骤2：对
 * / 
进行排序if（criterias.hasOneSortedColumn（））{
 
 List< String> ; orderParams = new ArrayList< String>（）; 
 queryBuilder.append（ORDER BY）; （ColumnDef columnDef：criterias.getSortingColumnDefs（））{
 orderParams.add（p。+ columnDef.getName（）++ columnDef.getSortDirection（））的
。 
} 
 
迭代器< String> itr2 = orderParams.iterator（）; 
 while（itr2.hasNext（））{
 queryBuilder.append（itr2.next（））; 
 if（itr2.hasNext（））{
 queryBuilder.append（，）; 
} 
} 
} 
 
 TypedQuery< Person> query = entityManager.createQuery（queryBuilder.toString（），Person.class）; 
 $ b $ ** 
 *步骤3：分页
 * / 
 query.setFirstResult（criterias.getDisplayStart（））; 
 query.setMaxResults（criterias.getDisplaySize（））; 
 
返回query.getResultList（）; 
} 
 
 / ** 
 *< p> 
 *用于返回过滤人数的查询。 
 * 
 * @param标准
 *用于过滤人员的DataTables标准。 
 *（maxResult，过滤，分页，...）
 * @返回过滤的人数。 
 * / 
 @Override 
 public Long getFilteredCount（DatatablesCriterias标准）{
 
 StringBuilder queryBuilder = new StringBuilder（SELECT p FROM Person p）; 
 
 queryBuilder.append（PersonRepositoryUtils.getFilterQuery（criterias））; 
 
查询查询= entityManager.createQuery（queryBuilder.toString（））; 
 return Long.parseLong（String.valueOf（query.getResultList（）。size（）））; 
} 
 
 / ** 
 * @返回总人数。 
 * / 
 @Override 
 public Long getTotalCount（）{
 Query query = entityManager.createQuery（SELECT COUNT（p）FROM Person p）; 
 return（Long）query.getSingleResult（）; 
 
 $ / code> 

我的问题是我需要重复编码数据访问层，它是对我所有的实体完全一样。现在，即时通讯思想有一个GENERIC实现。有人可以给我这个解决方案。对于任何使用Dandelion Datatables插件的人来说，这都是一个很好的帮助。

解决方案

因为最近我从事同样的任务，可以给出几个建议。
首先你应该看一下 Spring Data ，因为那部分Spring框架为您提供了数据库访问级别所需的一切。
您将需要创建一个扩展 JpaRepository 的 @Repository ，然后从这里查询数据库。
例如，getTotalCount可能会被 findAll（）方法替代，该方法返回所有实体的列表，甚至更简单，并带有 count（）方法。
然后，带有分页的数据可以通过 findAll（Pageable pageable）来获取，您只需要传递 new PageRequest（criterias.getStart（ ），criterias.getLength（））作为参数。
排序选项也可以通过Sort类在Spring Data中使用，并且它与Dandelion DatatablesCriterias和ColumnDef类非常巧妙地结合在一起。
对于更复杂的查询，您可以使用 @Query 和 @Param 注释。
因此，有关春季数据的更多具体信息，最好提出新问题。


I found samples on how to implement ajax server-side processing. On the controller the code looks like this.

@RequestMapping(value = "/persons")
public @ResponseBody
DatatablesResponse<Person> findAllForDataTablesFullSpring(@DatatablesParams DatatablesCriterias criterias) {
    DataSet<Person> dataSet = personService.findPersonsWithDatatablesCriterias(criterias);
    return DatatablesResponse.build(dataSet, criterias);
}

On the service layer

    public DataSet<Person> findPersonsWithDatatablesCriterias(DatatablesCriterias criterias) {

    List<Person> persons = personRepository.findPersonWithDatatablesCriterias(criterias);
    Long count = personRepository.getTotalCount();
    Long countFiltered = personRepository.getFilteredCount(criterias);

    return new DataSet<Person>(persons, count, countFiltered);
   }

On the data access layer

@Override
public List<Person> findPersonWithDatatablesCriterias(DatatablesCriterias criterias) {

    StringBuilder queryBuilder = new StringBuilder("SELECT p FROM Person p");

    /**
     * Step 1: global and individual column filtering
     */
    queryBuilder.append(PersonRepositoryUtils.getFilterQuery(criterias));

    /**
     * Step 2: sorting
     */
    if (criterias.hasOneSortedColumn()) {

        List<String> orderParams = new ArrayList<String>();
        queryBuilder.append(" ORDER BY ");
        for (ColumnDef columnDef : criterias.getSortingColumnDefs()) {
            orderParams.add("p." + columnDef.getName() + " " + columnDef.getSortDirection());
        }

        Iterator<String> itr2 = orderParams.iterator();
        while (itr2.hasNext()) {
            queryBuilder.append(itr2.next());
            if (itr2.hasNext()) {
                queryBuilder.append(" , ");
            }
        }
    }

    TypedQuery<Person> query = entityManager.createQuery(queryBuilder.toString(), Person.class);

    /**
     * Step 3: paging
     */
    query.setFirstResult(criterias.getDisplayStart());
    query.setMaxResults(criterias.getDisplaySize());

    return query.getResultList();
}

/**
 * <p>
 * Query used to return the number of filtered persons.
 * 
 * @param criterias
 *            The DataTables criterias used to filter the persons.
 *            (maxResult, filtering, paging, ...)
 * @return the number of filtered persons.
 */
    @Override
public Long getFilteredCount(DatatablesCriterias criterias) {

    StringBuilder queryBuilder = new StringBuilder("SELECT p FROM Person p");

    queryBuilder.append(PersonRepositoryUtils.getFilterQuery(criterias));

    Query query = entityManager.createQuery(queryBuilder.toString());
    return Long.parseLong(String.valueOf(query.getResultList().size()));
}

/**
 * @return the total count of persons.
 */
    @Override
public Long getTotalCount() {
    Query query = entityManager.createQuery("SELECT COUNT(p) FROM Person p");
    return (Long) query.getSingleResult();
}

My problem with this is I need to repeat coding the data access layer which is completely the same for all of my entities. Now, im thinking of having a GENERIC implementation. Can someone give me solution for this. It would be a great help for anyone using Dandelion Datatables plugin.

解决方案

Since, recently I worked on same kind of task, I can give a couple of suggestions. First of all you should definitely take a look at Spring Data since that part of Spring framework provides you with everything you would need for database access level. You will need to create a @Repository that extends JpaRepository, and then from here querying your database. So, for example, getTotalCount could be would be substituted with findAll() method, that returns a List of all entities, or even simpler, with count() method. Then, data with pagination could be retrieved with findAll(Pageable pageable) where you just need to pass new PageRequest(criterias.getStart(), criterias.getLength()) as a parameter. Sorting option is also available in Spring Data via Sort class and it works pretty neat with Dandelion DatatablesCriterias and ColumnDef classes. For more complex queries you could use @Query and @Param annotations. So, for more specific info regarding spring data it's better to ask new questions.

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