java/src/main/com/google/appengine/api/search/checkers/ListRequestChecker.java

   1 // Copyright 2011 Google Inc. All Rights Reserved.
   2
   3 package com.google.appengine.api.search.checkers;
   4
   5 import com.google.appengine.api.search.SearchServicePb.ListDocumentsParams;
   6 import com.google.appengine.api.search.Util;
   7
   8 /**
   9  * Checks values of {@link com.google.appengine.api.search.ListRequest}.
  10  *
  11  */
  12 public class ListRequestChecker {
  13   /**
  14    * The maximum number of documents which can be requested.
  15    */
  16   public static final int MAXIMUM_LIMIT = 1000;
  17
  18   /**
  19    * The default number of documents requested.
  20    */
  21   public static final int DEFAULT_LIMIT = 100;
  22
  23   /**
  24    * Checks whether the number of documents to return is between 0 and the
  25    * maximum.
  26    *
  27    * @param limit the maximum number of documents to return in results list
  28    * @return the checked number of documents to return
  29    * @throws IllegalArgumentException if the number of documents to return
  30    * is out of range
  31    */
  32   public static int checkLimit(int limit) {
  33     Preconditions.checkArgument(limit >= 0 && limit <= MAXIMUM_LIMIT,
  34         String.format("The limit %d must be between 0 and %d",
  35             limit, MAXIMUM_LIMIT));
  36     return limit;
  37   }
  38
  39   /**
  40    * Checks whether the given start document Is legal.
  41    *
  42    * @param startDocId the start ocument Id to be checked.
  43    * @return the checked start document Id.
  44    * @throws IllegalArgumentException if the start document Id is illegal.
  45    */
  46   public static String checkStartDocId(String startDocId) {
  47     if (Util.isNullOrEmpty(startDocId)) {
  48       return startDocId;
  49     }
  50     return DocumentChecker.checkDocumentId(startDocId);
  51   }
  52
  53   /**
  54    * Checks the values of the {@link ListDocumentsParams} params.
  55    *
  56    * @param params The {@link ListDocumentsParams} to check
  57    * @return the checked params
  58    * @throws IllegalArgumentException if some of the values of params are
  59    * invalid
  60    */
  61   public static ListDocumentsParams checkListDocumentsParams(ListDocumentsParams params) {
  62     IndexChecker.checkName(params.getIndexSpec().getName());
  63     if (params.hasLimit()) {
  64       checkLimit(params.getLimit());
  65     }
  66     if (params.hasStartDocId()) {
  67       DocumentChecker.checkDocumentId(params.getStartDocId());
  68     }
  69     return params;
  70   }
  71 }