8.4 Enum Type Handler

dbVisitor automatically selects EnumTypeHandler for enum types, so no intervention is usually needed.

Object mapping with an enum field

public class User {
    private UserType userType;

    // getters and setters omitted
}

No special handling needed for queries and parameters

// Enum fields in query results are automatically converted
jdbc.queryForList("select * from users", User.class);

// Enum parameters are also handled automatically
User userInfo = ...;
jdbc.queryForList("select * from users where user_type = #{userType}", userInfo);

info

By default, EnumTypeHandler maps using the enum's name() value to match database fields (string-based).

Explicit Declaration

Explicitly specify in parameter passing

jdbc.queryForList(
    "select * from users where user_type = #{userType, typeHandler=net.hasor.dbvisitor.types.handler.string.EnumTypeHandler}",
    userInfo
);

Explicitly specify in object mapping

public class User {
    @Column(typeHandler = EnumTypeHandler.class)
    private UserType userType;

    // getters and setters omitted
}

• EnumTypeHandler full class name: net.hasor.dbvisitor.types.handler.string.EnumTypeHandler

Map Numeric Values to Enums

If the database stores numeric values, the enum needs to implement the EnumOfValue interface to convert between numbers and enum values.

public enum LicenseEnum implements EnumOfValue<LicenseEnum> {
    Private(0),
    AGPLv3(1),
    GPLv3(2);

    private final int type;

    LicenseEnum(int type) {
        this.type = type;
    }

    public int codeValue() {
        return this.type;
    }

    public LicenseEnum valueOfCode(int codeValue) {
        for (LicenseEnum item : LicenseEnum.values()) {
            if (item.codeValue() == codeValue) {
                return item;
            }
        }
        return null;
    }
}

• The EnumOfValue interface is in the net.hasor.dbvisitor.types.handler.string package

Map Codes to Enums

When the enum's name() cannot be used directly as the database mapping value, the enum can implement the EnumOfCode interface to customize string mapping logic.

public enum LicenseEnum implements EnumOfCode<LicenseEnum> {
    Private("private_license"),
    AGPLv3("agpl_v3"),
    GPLv3("gpl_v3");

    private final String code;

    LicenseEnum(String code) {
        this.code = code;
    }

    public String codeName() {
        return this.code;
    }

    public LicenseEnum valueOfCode(String codeValue) {
        for (LicenseEnum item : LicenseEnum.values()) {
            if (item.codeName().equalsIgnoreCase(codeValue)) {
                return item;
            }
        }
        return null;
    }
}

• The EnumOfCode interface is in the net.hasor.dbvisitor.types.handler.string package
• If the enum already has a default codeName() method (returning name()), you only need to override the valueOfCode method