java - 无法将文档作为 Java 类读取

Question

我正在使用 ArangoDB 3.1.23 和 ArangoDB Java 驱动程序 4.2.2。我正在使用 Eclipse 和 Maven。我在读取 Java 类文档时遇到了麻烦，正如它所解释的 here 。我按照教程编写了以下测试代码。

如您所见，以 BaseDocument 或 VelocyPack 形式读取文档是可行的，但以 Java 类形式读取它们会返回 null。

public static void main(String[] args) {

    class MyObject {

        private String key;
        private String name;
        private int age;

        public MyObject(String name, int age) {
            this();
            this.name = name;
            this.age = age;
        }

        public MyObject() {
            super();
        }
    }  

    final String dbName = "testdb";
    final String collName = "testCollection";

    ArangoDB arangoDB = new ArangoDB.Builder().user("root").password("").build();

    // Delete existing database
    try{
        System.out.println("Deleted existing " + dbName + " database: " + arangoDB.db(dbName).drop());
    } catch (Exception e) {
        System.err.println("Error while deleting database " + dbName);
    }

    // Test database creation
    try {
        arangoDB.createDatabase(dbName);
        System.out.println("Created database " + dbName);
    } catch (Exception e) {
        System.err.println("Did not create database " + dbName);
    }

    // Test collection creation
    try {
        arangoDB.db(dbName).createCollection(collName);
        System.out.println("Created collection " + collName);
    } catch (Exception e) {
        System.err.println("Did not create collection " + collName);
    }

    // Test custom class document insertion
    String key1 = null;
    try {
        MyObject myObject = new MyObject("Homer", 38);
        key1 = arangoDB.db(dbName).collection(collName).insertDocument(myObject).getKey();
        System.out.println("Inserted new document as MyObject. key: " + myObject.key + ", " + key1);
    } catch (Exception e) {
        System.err.println("Did not insert new document");
    }

    // Test BaseDocument class document insertion
    String key2 = null;
    try {
        BaseDocument myBaseDocument = new BaseDocument();
        myBaseDocument.addAttribute("name", "Paul");
        myBaseDocument.addAttribute("age", 23);
        key2 = arangoDB.db(dbName).collection(collName).insertDocument(myBaseDocument).getKey();
        System.out.println("Inserted new document as BaseDocument. key: " + myBaseDocument.getKey() + ", " + key2);
    } catch (Exception e) {
        System.err.println("Did not insert new document");
    }

    // Test read as VPackSlice
    String keyToRead1 = key1;
    VPackSlice doc1 = arangoDB.db(dbName).collection(collName).getDocument(keyToRead1, VPackSlice.class);
    if (doc1 != null)
        System.out.println("Open document " + keyToRead1 + "  VPackSlice: " + doc1.get("name").getAsString() + " " + doc1.get("age").getAsInt());
    else
        System.err.println("Could not open the document " + keyToRead1 + " using VPackSlice");

    // Test read as BaseDocument
    String keyToRead2 = key1;
    BaseDocument doc2 = arangoDB.db(dbName).collection(collName).getDocument(keyToRead2, BaseDocument.class);
    if (doc2 != null)
        System.out.println("Open document " + keyToRead2 + " as BaseDocument: " + doc2.getAttribute("name") + " " + doc2.getAttribute("age"));
    else
        System.err.println("Could not open the document " + keyToRead2 + " as BaseDocument");

    // Test read as MyObject
    String keyToRead3 = key1;
    MyObject doc3 = arangoDB.db(dbName).collection(collName).getDocument(keyToRead3, MyObject.class);
    if (doc3 != null)
        System.out.println("Open document " + keyToRead3 + " as MyObject: " + doc3.name + " " + doc3.age);
    else
        System.err.println("Could not open the document " + keyToRead3 + " as MyObject");
}

结果:

SLF4J: Failed to load class "org.slf4j.impl.StaticLoggerBinder".
SLF4J: Defaulting to no-operation (NOP) logger implementation
SLF4J: See http://www.slf4j.org/codes.html#StaticLoggerBinder for further details.
Deleted existing testdb database: true
Created database testdb
Created collection testCollection
Inserted new document as MyObject. key: null, 3510088
Inserted new document as BaseDocument. key: 3510092, 3510092
Open document 3510088  VPackSlice: Homer 38
Open document 3510088 as BaseDocument: Homer 38
Could not open the document 3510088 as MyObject

Answer 1

我可以通过将 MyObject 移动到它自己的文件来使您的示例正常工作。我认为这可能是由于内联对象造成的，因为我尝试内联添加注释和 getters/setters，但这也不起作用。就像这样:

import com.arangodb.entity.DocumentField;
import com.arangodb.entity.DocumentField.Type;

public class MyObject {
    @DocumentField(Type.KEY)
    private String key;
    public String getKey() {
        return key;
    }

    public void setKey(String key) {
        this.key = key;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }

    private String name;
    private int age;

    public MyObject(String name, int age) {
        this();
        this.name = name;
        this.age = age;
    }

    public MyObject() {
        super();
    }
}

还有

// Test read as MyObject
String keyToRead3 = key1;
MyObject doc3 = arangoDB.db(dbName).collection(collName).getDocument(keyToRead3, MyObject.class);
if (doc3 != null)
   System.out.println("Open document " + keyToRead3 + " as MyObject: " + doc3.getName() + " " + doc3.getAge());
else
   System.err.println("Could not open the document " + keyToRead3 + " as MyObject"); 

哪个产生

Inserted new document as MyObject. key: 7498620, 7498620
Inserted new document as BaseDocument. key: 7498624, 7498624
Open document 7498620  VPackSlice: Homer 38
Open document 7498620 as BaseDocument: Homer 38
Open document 7498620 as MyObject: Homer 38