me.zzp.ar.Association Maven / Gradle / Ivy

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package me.zzp.ar;

import java.util.Map;
import me.zzp.ar.ex.UndefinedAssociationException;

/**
 * 表之间的关联。
 * 
 * @since 1.0
 * @author redraiment
 */
public final class Association {
  private final Map relations;
  private final boolean onlyOne;
  private final boolean ancestor;

  private Association assoc;
  String target;
  String key;

  Association(Map relations, String name, boolean onlyOne, boolean ancestor) {
    this.relations = relations;
    this.onlyOne = onlyOne;
    this.ancestor = ancestor;

    this.target = name;
    this.key = name.concat("_id");
    this.assoc = null;
  }

  public boolean isOnlyOneResult() {
    return onlyOne;
  }

  public boolean isAncestor() {
    return ancestor;
  }
  
  public boolean isCross() {
    return assoc != null;
  }

  public Association by(String key) {
    this.key = key;
    return this;
  }

  public Association in(String table) {
    this.target = table;
    return this;
  }

  public Association through(String assoc) {
    assoc = DB.parseKeyParameter(assoc);
    if (relations.containsKey(assoc)) {
      this.assoc = relations.get(assoc);
    } else {
      throw new UndefinedAssociationException(assoc);
    }
    return this;
  }

  String assoc(String source, int id) {
    String template = isAncestor()? "%1$s on %2$s.%3$s = %1$s.id": "%1$s on %1$s.%3$s = %2$s.id";
    if (isCross()) {
      return String.format(template, assoc.target, target, key).concat(" join ").concat(assoc.assoc(source, id));
    } else {
      return String.format(template.concat(" and %1$s.id = %4$d"), source, target, key, id);
    }
  }
}