By Custom nGQL ​

• When using this method, the familiarity with nGQL and cypher will be higher. Developers who are not familiar with it can learn about it through【What Is nGQL】.

• In addition, the template engine used here is Beetl.

  • Beetl Docs-Delimiters And Placeholder Symbols, mainly look at placeholders. Ngbatis has made variable settings. If it is only parameter filling, you can ignore the use of delimiters. 【See [Param Usage] for details】 However, parameter condition control and parameter loop delimiter are almost inevitable. Due to the difference in configuration of Beetl in ngbatis, if the delimiter is involved in the document, the <% %> will be replaced by @ \n, for example:

diff

- <%if ( aBool ) { 
-                         
- } %>                
+ @if ( aBool ) {
+                       
+ @}

• Beetl Docs-Functions Used to Process Parameters
• Beetl Docs-Condition Control Statements【See Param Condition Control for details】
• Beetl Docs-Loop Statements【See Param Loop for details】
• Beetl-Online test widget

The same as By Basic DAO, We need to create a XXXDao.java file and XXXDao.xml file.

Creating file in Dao layer ​

Create a Dao corresponding to Person. If you do not need to use the basic class method, it is unnecessary to inherit NebulaDaoBasic ​

package your.domain;

import  org.nebula.contrib.ngbatis.proxy.NebulaDaoBasic;

public interface PersonDao {

}

Create a file named PersonDao.xml file. The default location is: /resources/mapper ​

<mapper namespace="your.domain.PersonDao">

</mapper>

XXXDao.java does not need to be annotated by @Mapper or @Component, it will be discovered by namespace and automatically registered as a bean. The premise is that the namespace needs to be in the scanBasePackages value under the @SpringBootApplication annotation. For example: @SpringBootApplication( scanBasePackages = { "your.domain", "org.nebula.contrib" } )

How to let Java programs execute nGQL | cypher through ngbatis ​

Take a simple query statement as an example ​

Adding interface in PersonDao.java ​

Integer select1();

In the current version, the return value type and method parameter type of the interface. If it is a basic type, only the wrapper class is supported. For example, please write int as Integer.

Adding a tag in PersonDao.xml ​

<select id="select1">
    RETURN 1
  </select>

Integer result = personDao.select1(); // result : 1

Referencing an nGQL Fragment ​

Reference a statement like MyBatis's include tag.

NgBatis uses the built-in function ng.include for referencing. The description of ng.include can be found in Ngbatis Built-in Functions and Variables.

Define Dao Interface ​

<!-- Omit this if the space is consistent with the declaration in the yml file -->
  <mapper namespace="your.domain.TestDao" space="test">

      <!-- Define nGQL fragments anywhere within the mapper node in the XML file -->
      <nGQL id="my-ngql-id">
        ${myInt}
      </nGQL>

      <!-- Define interface method statement -->
      <select id="returnMyInt" resultType="java.lang.Integer">
        RETURN @ng.include('my-ngql-id');
      </select>

      <!-- extra param -->
      <select id="returnAge" resultType="java.lang.Integer">
        @ng.include('ngql-return-age',person);
      </select>

      <nGQL id="ngql-return-age">
        RETURN @ng.include('my-ngql-id',{'myInt':age});
      </nGQL>

  </mapper>

nGQL fragments automatically inherit the parameters passed by the Dao method and can be used directly within the nGQL fragment. You can also specify additional parameters on the ng.include function, which will be used with higher priority when generating statements. See the example above.

nGQL fragments are not limited in hierarchy, and an nGQL fragment can reference another nGQL fragment. However, considering performance, it is not recommended to have too many levels of nGQL statement references.

If you need to reference an nGQL fragment from another mapper, you need to prepend the namespace of the fragment to the fragment ID when using the ng.include function, like this: @ng.include('your.domain.XxxDao.nGQL-ID');