Add currentOffset to RKPaginator

Code/Network/RKPaginator.h

@@ -188,6 +188,14 @@
  */
 @property (nonatomic, readonly) NSUInteger currentPage;
 
+/**
+ Returns the offset based off the page for the most recently loaded objects.
+
+ @return The offset for the current page of objects.
+ @exception NSInternalInconsistencyException Raised if `isLoaded` is equal to `NO`.
+ */
+@property (nonatomic, readonly) NSUInteger offset;
+
 /**
  Returns the number of pages in the total resource collection.
 

Code/Network/RKPaginator.m

@@ -36,6 +36,7 @@ @interface RKPaginator ()
 @property (nonatomic, strong) RKObjectRequestOperation *objectRequestOperation;
 @property (nonatomic, copy) NSArray *responseDescriptors;
 @property (nonatomic, assign, readwrite) NSUInteger currentPage;
+@property (nonatomic, assign, readwrite) NSUInteger offset;
 @property (nonatomic, assign, readwrite) NSUInteger pageCount;
 @property (nonatomic, assign, readwrite) NSUInteger objectCount;
 @property (nonatomic, assign, readwrite) BOOL loaded;
@@ -71,6 +72,7 @@ - (id)initWithRequest:(NSURLRequest *)request
         self.currentPage = NSNotFound;
         self.pageCount = NSNotFound;
         self.objectCount = NSNotFound;
+        self.offset = NSNotFound;
         self.perPage = RKPaginatorDefaultPerPage;
         self.loaded = NO;
     }
@@ -114,6 +116,11 @@ - (BOOL)hasCurrentPage
     return _currentPage != NSNotFound;
 }
 
+- (BOOL)hasOffset
+{
+    return _offset != NSNotFound;
+}
+
 - (BOOL)hasPageCount
 {
     return _pageCount != NSNotFound;
@@ -131,6 +138,12 @@ - (NSUInteger)currentPage
     return _currentPage;
 }
 
+- (NSUInteger)offset
+{
+    if ([self hasOffset]) return _offset;
+    return [self hasCurrentPage] ? ((_currentPage - 1) * _perPage) : 0;
+}
+
 - (BOOL)hasNextPage
 {
     NSAssert(self.isLoaded, @"Cannot determine hasNextPage: paginator is not loaded.");
@@ -227,9 +240,10 @@ - (void)waitUntilFinished
 
 - (NSString *)description
 {
-    return [NSString stringWithFormat:@"<%@: %p patternURL=%@ isLoaded=%@ perPage=%ld currentPage=%@ pageCount=%@ objectCount=%@>",
+    return [NSString stringWithFormat:@"<%@: %p patternURL=%@ isLoaded=%@ perPage=%ld currentPage=%@ offset=%@ pageCount=%@ objectCount=%@>",
             NSStringFromClass([self class]), self, self.patternURL, self.isLoaded ? @"YES" : @"NO", (long) self.perPage,
             [self hasCurrentPage] ? @(self.currentPage) : @"???",
+            [self hasOffset] ? @(self.offset) : @"???",
             [self hasPageCount] ? @(self.pageCount) : @"???",
             [self hasObjectCount] ? @(self.objectCount) : @"???"];
 }
@@ -292,4 +306,14 @@ - (void)setObjectCountNumber:(NSNumber *)objectCountNumber
     self.objectCount = [objectCountNumber unsignedIntegerValue];
 }
 
+- (NSNumber *)offsetNumber
+{
+    return [NSNumber numberWithUnsignedInteger:self.offset];
+}
+
+- (void)setOffsetNumber:(NSNumber *)offsetNumber
+{
+    self.offset = [offsetNumber unsignedIntegerValue];
+}
+
 @end

Tests/Logic/ObjectMapping/RKPaginatorTest.m

@@ -36,6 +36,7 @@ @interface RKPaginatorTest : RKTestCase
 @implementation RKPaginatorTest
 
 static NSString * const RKPaginatorTestResourcePathPattern = @"/paginate?per_page=:perPage&page=:currentPage";
+static NSString * const RKPaginatorTestResourcePathPatternWithOffset = @"/paginate?limit=:perPage&offset=:offset";
 
 - (void)setUp
 {
@@ -61,6 +62,7 @@ - (RKObjectMapping *)paginationMapping
     [paginationMapping addPropertyMapping:[RKAttributeMapping attributeMappingFromKeyPath:@"current_page" toKeyPath:@"currentPage"]];
     [paginationMapping addPropertyMapping:[RKAttributeMapping attributeMappingFromKeyPath:@"per_page" toKeyPath:@"perPage"]];
     [paginationMapping addPropertyMapping:[RKAttributeMapping attributeMappingFromKeyPath:@"total_entries" toKeyPath:@"objectCount"]];
+    [paginationMapping addPropertyMapping:[RKAttributeMapping attributeMappingFromKeyPath:@"offset" toKeyPath:@"offset"]];
 
     return paginationMapping;
 }
@@ -70,6 +72,11 @@ - (NSURL *)paginationURL
     return [NSURL URLWithString:RKPaginatorTestResourcePathPattern relativeToURL:[RKTestFactory baseURL]];
 }
 
+- (NSURL *)paginationOffsetURL
+{
+    return [NSURL URLWithString:RKPaginatorTestResourcePathPatternWithOffset relativeToURL:[RKTestFactory baseURL]];
+}
+
 #pragma mark - Test Cases
 
 - (void)testInitCopiesPatternURL
@@ -145,6 +152,17 @@ - (void)testThatURLReturnedReflectsStateOfPaginator
     expect([[mockPaginator URL] query]).to.equal(@"per_page=25&page=1");
 }
 
+- (void)testThatURLReturnedReflectsStateOfPaginatorWithOffset
+{
+    NSURLRequest *request = [NSURLRequest requestWithURL:self.paginationOffsetURL];
+    RKPaginator *paginator = [[RKPaginator alloc] initWithRequest:request paginationMapping:self.paginationMapping responseDescriptors:@[ self.responseDescriptor ]];
+    id mockPaginator = [OCMockObject partialMockForObject:paginator];
+    NSUInteger currentPage = 1;
+    [[[mockPaginator stub] andReturnValue:OCMOCK_VALUE(currentPage)] currentPage];
+    expect([[mockPaginator URL] query]).to.equal(@"limit=25&offset=0");
+}
+
+
 - (void)testLoadingAPageOfObjects
 {
     NSURLRequest *request = [NSURLRequest requestWithURL:self.paginationURL];
@@ -410,4 +428,16 @@ - (void)testPaginatorWithPaginationURLThatIncludesTrailingSlash
     expect(paginator.objectCount).to.equal(0);
 }
 
+- (void)testOffsetNumberOfNextPage
+{
+    NSURLRequest *request = [NSURLRequest requestWithURL:self.paginationURL];
+    RKPaginator *paginator = [[RKPaginator alloc] initWithRequest:request paginationMapping:self.paginationMapping responseDescriptors:@[ self.responseDescriptor ]];
+    [paginator loadPage:1];
+    [paginator waitUntilFinished];
+    expect(paginator.offset).to.equal(0);
+    [paginator loadNextPage];
+    [paginator waitUntilFinished];
+    expect(paginator.offset).to.equal(3);
+}
+
 @end