ManyManyLinkField.java

package org.nutz.dao.impl.entity.field;

import org.nutz.dao.Cnd;
import org.nutz.dao.Condition;
import org.nutz.dao.Sqls;
import org.nutz.dao.entity.Entity;
import org.nutz.dao.entity.LinkType;
import org.nutz.dao.entity.PkType;
import org.nutz.dao.impl.EntityHolder;
import org.nutz.dao.impl.entity.EntityName;
import org.nutz.dao.impl.entity.info.LinkInfo;
import org.nutz.dao.util.cri.SimpleCriteria;
import org.nutz.lang.Lang;
import org.nutz.lang.Strings;

public class ManyManyLinkField extends AbstractLinkField {

    private EntityName relationTableName;

    private String fromColumnName;

    private String toColumnName;

    public ManyManyLinkField(Entity<?> host, EntityHolder holder, LinkInfo info) {
        super(host, holder, info);
        this.targetType = info.manymany.target();
        this.mapKey = info.manymany.key();
        this.relationTableName = EntityName.create(info.manymany.relation());

        String[] ss = Strings.splitIgnoreBlank(info.manymany.from(), ":");
        this.fromColumnName = ss[0];
        String fromField = ss.length > 1 ? ss[1] : null;

        ss = Strings.splitIgnoreBlank(info.manymany.to(), ":");
        this.toColumnName = ss[0];
        String toField = ss.length > 1 ? ss[1] : null;

        /*
         * 开始分析两个实体的链接字段
         */
        Entity<?> ta = this.getLinkedEntity();

        // 用户指定了 "from" 的 Java 字段名
        if (fromField != null) {
            hostField = host.getField(fromField);
        }
        // 用户指定了 "to" 的 Java 字段名
        if (null != toField) {
            linkedField = ta.getField(toField);
        }

        // 用户仅仅指定了 "from" 的 Java 字段
        if (null != hostField && linkedField == null) {
            linkedField = ta.getPkType() == PkType.ID ? ta.getIdField() : ta.getNameField();
        }
        // 用户仅仅指定了 "to" 的 Java 字段
        else if (null == hostField && linkedField != null) {
            hostField = host.getPkType() == PkType.ID ? host.getIdField() : host.getNameField();
        }
        // 都没指定，优先使用 Id 的链接主键
        else {
            // 都有 ID
            if (null != host.getIdField() && null != ta.getIdField()) {
                hostField = host.getIdField();
                linkedField = ta.getIdField();
            }
            // 宿主ID，链 Name
            else if (null != host.getIdField() && null != ta.getNameField()) {
                hostField = host.getIdField();
                linkedField = ta.getNameField();
            }
            // 宿主Name 链 ID
            else if (null != host.getNameField() && null != ta.getIdField()) {
                hostField = host.getNameField();
                linkedField = ta.getIdField();
            }
            // 都有 Name
            else if (null != host.getNameField() && null != ta.getNameField()) {
                hostField = host.getNameField();
                linkedField = ta.getNameField();
            }

        }
        // 最后再检查一下 ...
        if (null == hostField || null == linkedField) {
            throw Lang.makeThrow(    "Invalid @ManyMany in '%s'(%s): lack @Id or @Name",
                                    info.name,
                                    host.getType().getName());
        }

    }

    public Condition createCondition(Object host) {
        SimpleCriteria cri = Cnd.cri();
        cri.where().andInBySql(    linkedField.getColumnName(),
                                "SELECT %s FROM %s WHERE %s=%s",
                                toColumnName,
                                this.getRelationName(),
                                fromColumnName,
                                Sqls.formatFieldValue(hostField.getValue(host)));
        return cri;
    }

    public void updateLinkedField(Object obj, Object linked) {}

    public void saveLinkedField(Object obj, Object linked) {}

    public LinkType getLinkType() {
        return LinkType.MANYMANY;
    }

    public String getRelationName() {
        return this.relationTableName.value();
    }

    public String getFromColumnName() {
        return fromColumnName;
    }

    public String getToColumnName() {
        return toColumnName;
    }

    /**
     * 返回关联两个实体的主键 Java 字段名数组
     * <p>
     * 数组的第一个元素是宿主主键的字段名，第二个元素是映射实体的主键字段名
     * 
     * @return 关联两个实体的主键 Java 字段名数组
     */
    public String[] getLinkedPkNames() {
        String[] re = new String[2];
        re[0] = hostField.getName();
        re[1] = linkedField.getName();
        return re;
    }

}