internal static void AssertIsUnbounded(PageNumberAndSize unboundedPage)
{
Assert.IsTrue(unboundedPage.IsUnbounded);
Assert.AreEqual(byte.MinValue, unboundedPage.Size);
AssertIsFirstPage(unboundedPage);
}
/// <summary>
/// Initializes a new instance of the <see cref="PagingInfo"/> struct
/// upon deserialization of another <see cref="PagingInfo"/> which
/// this one replaces, used for lazy initialization by the internal
/// <see cref="Calculator"/> property.
/// </summary>
/// <param name="calculator">
/// A <see cref="PagingInfoCalculator"/> value initialized from
/// the <see cref="CurrentPage"/> and <see cref="TotalItems"/>
/// values of a <see cref="PagingInfo"/> value to be replaced
/// by this new instance. To understand how this works,
/// refer to the <see cref="Calculator"/> property.
/// </param>
private PagingInfo(PagingInfoCalculator calculator)
{
this.CurrentPage = calculator.CurrentPage;
this.TotalItems = calculator.TotalItems;
this.calculator = calculator;
this.calculateAllPagesAndItemNumbers = calculator.IncludeAllPagesAndItemNumbers;
}
internal static void AssertIsFirstPage(PageNumberAndSize firstPage)
{
Assert.IsTrue(firstPage.HasValue);
Assert.GreaterOrEqual(firstPage.Size, byte.MinValue);
Assert.AreEqual(PageNumberAndSize.FirstPageNumber, firstPage.Number);
Assert.AreEqual(0, firstPage.Index);
}
internal static void AssertIsEmpty(PageNumberAndSize emptyPage)
{
Assert.IsFalse(emptyPage.HasValue);
Assert.IsFalse(emptyPage.IsUnbounded);
Assert.AreEqual(byte.MinValue, emptyPage.Size);
Assert.AreEqual(0, emptyPage.Number);
Assert.AreEqual(-1, emptyPage.Index);
}
/// <summary>
/// Initializes a new instance of the <see cref="PagingInfo"/> struct
/// based on a given <see cref="PageNumberAndSize"/> value.
/// </summary>
/// <param name="requestedPage">
/// The requested page <see cref="PageNumberAndSize.Number"/>
/// and <see cref="PageNumberAndSize.Size"/>.
/// If <see cref="PageNumberAndSize.Unbounded"/> is sent,
/// all of the items are returned on a single page as large
/// as the number of <paramref name="totalItems"/>.
/// </param>
/// <param name="totalItems">
/// The total number of items in the collection to be paged,
/// initial value for the immutable <see cref="TotalItems"/> field.
/// </param>
/// <param name="calculateAllPagesAndItemNumbers">
/// Indicates whether to include a representation of every
/// page and its item numbers in the serialized version of
/// this <see cref="PagingInfo"/>, as a list of
/// <see cref="PageNumberAndItemNumbers"/>,
/// for a paging widget which may want to use them.
/// </param>
public PagingInfo(
PageNumberAndSize requestedPage, int totalItems, bool calculateAllPagesAndItemNumbers = DefaultCalculateAllPagesAndItemNumbers)
: this(new PagingInfoCalculator(requestedPage, totalItems, calculateAllPagesAndItemNumbers))
{
Contract.Requires <ArgumentException>(
requestedPage.HasValue, "The current page must have a value. \"Unbounded\" is an acceptable value.");
Contract.Requires <ArgumentOutOfRangeException>(
totalItems >= 0, "The number of items in the list must not be negative!");
}
public void Deserializes_As_Invalid_From_Negative_Page_Number()
{
PageNumberAndSize deserializedPage
= JsonConvert.DeserializeObject <PageNumberAndSize>(
"{\"Number\":-7,\"Size\":10}");
Assert.IsFalse(deserializedPage.HasValue);
Assert.IsFalse(deserializedPage.IsUnbounded);
}
public void Deserializes_And_Ignores_Inconsistency_From_Excessive_Specification()
{
PageNumberAndSize page = new PageNumberAndSize(7, 20);
PageNumberAndSize deserializedPage
= JsonConvert.DeserializeObject <PageNumberAndSize>(
"{\"Number\":7,\"Size\":20,\"Index\":1111111,\"IsUnbounded\":true}"); // ,\"HasValue\":false
AssertEquality(page, deserializedPage);
}
public void Deserializes_From_Minimal_Specification()
{
PageNumberAndSize page = new PageNumberAndSize(7);
PageNumberAndSize deserializedPage
= JsonConvert.DeserializeObject <PageNumberAndSize>(
"{\"Number\":7,\"Size\":10}");
AssertEquality(page, deserializedPage);
}
public void Serializes_All_Properties()
{
PageNumberAndSize page = new PageNumberAndSize(7, 20);
string serializedPage = JsonConvert.SerializeObject(page);
Assert.AreEqual(
"{\"Number\":7,\"Size\":20,\"Index\":6,\"IsUnbounded\":false}", // ,\"HasValue\":true
serializedPage);
}
public void ReturnsUnboundedFromUnbounded()
{
PagingInfo unboundedPagingInfo = new PagingInfo(PageNumberAndSize.Unbounded, 57);
PageNumberAndSize newPage = unboundedPagingInfo.TurnToPage(8);
Assert.AreEqual(1, newPage.Number);
Assert.AreEqual(0, newPage.Size);
Assert.IsTrue(newPage.IsUnbounded);
}
public void AllowsTurningPastLastPage()
{
PagingInfo validPagingInfo = new PagingInfo(3, 10, 57);
PageNumberAndSize newPage = validPagingInfo.TurnToPage(8);
Assert.AreEqual(8, newPage.Number);
Assert.AreEqual(10, newPage.Size);
Assert.IsFalse(newPage.IsUnbounded);
}
public void DefaultCaseReusesSize()
{
PagingInfo validPagingInfo = new PagingInfo(3, 10, 57);
PageNumberAndSize newPage = validPagingInfo.TurnToPage(2);
Assert.AreEqual(2, newPage.Number);
Assert.AreEqual(10, newPage.Size);
Assert.IsFalse(newPage.IsUnbounded);
}
internal static void AssertEquality(
PageNumberAndSize expected, PageNumberAndSize actual)
{
Assert.IsTrue(expected == actual);
Assert.IsFalse(expected != actual);
Assert.IsTrue(expected.Equals(actual));
Assert.AreEqual(expected, actual);
Assert.IsTrue(actual == expected);
Assert.IsFalse(actual != expected);
Assert.IsTrue(actual.Equals(expected));
Assert.AreEqual(actual, expected);
Assert.AreEqual(expected.Number, actual.Number);
Assert.AreEqual(expected.Size, actual.Size);
Assert.AreEqual(expected.Index, actual.Index);
Assert.AreEqual(expected.IsUnbounded, actual.IsUnbounded);
Assert.AreEqual(expected.HasValue, actual.HasValue);
}
/// <summary>
/// Initializes a new instance of the <see cref="PagingInfoCalculator"/> struct.
/// Invoked by the private <see cref="PagingInfo.Calculator"/>
/// property of an owner <see cref="PagingInfo"/> value,
/// calculates metadata for paging UI, optionally including
/// a list of all pages and item numbers. For effective lazy
/// initialization following deserialization from bare essentials.
/// </summary>
/// <param name="currentPage">
/// The page <see cref="PageNumberAndSize.Number"/>
/// and <see cref="PageNumberAndSize.Size"/>.
/// If <see cref="PageNumberAndSize.Unbounded"/> is sent,
/// all of the items are returned on a single page as large
/// as the number of <paramref name="totalItems"/>.
/// </param>
/// <param name="totalItems">
/// The total number of items in the collection to be paged,
/// initial value for the immutable <see cref="TotalItems"/> field.
/// </param>
/// <param name="includeAllPagesAndItemNumbers">
/// Whether to fill the set of <see cref="AllPages"/>
/// including the item numbers on each page,
/// which may be useful for some paging UI.
/// Relayed back to the <see cref="PagingInfo"/> via the
/// <see cref="IncludeAllPagesAndItemNumbers"/> field,
/// adds the private <see cref="PagingInfo.AllPages"/>
/// property to the serialization output for JSON.
/// </param>
internal PagingInfoCalculator(
PageNumberAndSize currentPage, int totalItems, bool includeAllPagesAndItemNumbers)
{
Contract.Requires <ArgumentException>(
currentPage.HasValue, "The current page must have a value. \"Unbounded\" is an acceptable value.");
Contract.Requires <ArgumentOutOfRangeException>(
totalItems >= 0, "The number of items in the list must not be negative!");
this.IncludeAllPagesAndItemNumbers = includeAllPagesAndItemNumbers;
this.CurrentPage = currentPage;
this.TotalItems = totalItems;
if (currentPage.IsUnbounded)
{
// This is the case where all of the items are returned on
// the list, and there is just one unbounded page of items.
// The total number of items may exceed the maximum allowed
// value of a byte, so the "page size" value remains as zero.
// Beware of division by zero!
// There are no calculations here based on the page size!
this.TotalPages = 1;
this.CurrentPage = PageNumberAndSize.Unbounded;
this.FirstItemNumber = this.TotalItems > 0 ? 1 : 0;
this.LastItemNumber = this.TotalItems;
this.ItemCount = this.TotalItems;
this.IsFirstPage = true;
this.IsLastPage = true;
this.PreviousPage = PageNumberAndSize.Empty;
this.NextPage = PageNumberAndSize.Empty;
this.FirstPage = this.CurrentPage;
this.LastPage = this.CurrentPage;
}
else
{
this.CurrentPage = currentPage;
if ((this.TotalItems > 0) && (this.CurrentPage.Size > 0))
{
// Calculate the total pages for a fixed page size and at least one result.
this.TotalPages = CalculateTotalPages(this.CurrentPage.Size, this.TotalItems);
// Handle the situation if someone turns past the last page.
if (this.CurrentPage.Number > this.TotalPages)
{
// Reset the current page to be the number of the last possible page.
this.CurrentPage = new PageNumberAndSize(this.TotalPages, this.CurrentPage.Size);
}
this.LastItemNumber = this.CurrentPage.Number * this.CurrentPage.Size;
this.FirstItemNumber = this.LastItemNumber - this.CurrentPage.Size + 1;
this.ItemCount = this.LastItemNumber - this.FirstItemNumber + 1;
this.IsFirstPage = this.CurrentPage.Number == PageNumberAndSize.FirstPageNumber;
this.IsLastPage = this.CurrentPage.Number == this.TotalPages;
if (this.IsFirstPage)
{
this.FirstPage = this.CurrentPage;
this.PreviousPage = PageNumberAndSize.Empty;
}
else
{
this.FirstPage = new PageNumberAndSize(
PageNumberAndSize.FirstPageNumber, this.CurrentPage.Size);
this.PreviousPage = new PageNumberAndSize(
this.CurrentPage.Number - 1, this.CurrentPage.Size);
}
if (this.IsLastPage)
{
this.LastPage = this.CurrentPage;
this.NextPage = PageNumberAndSize.Empty;
// The number of items shown on the last page
// may be smaller than the number of items per page.
this.LastItemNumber = this.TotalItems;
}
else
{
this.LastPage = new PageNumberAndSize(
this.TotalPages, this.CurrentPage.Size);
this.NextPage = new PageNumberAndSize(
this.CurrentPage.Number + 1, this.CurrentPage.Size);
}
}
else
{
// This is the case where the count of TotalItems is zero,
// so reset the page number back to the first page.
this.CurrentPage = new PageNumberAndSize(
PageNumberAndSize.FirstPageNumber, this.CurrentPage.Size);
// There is just one page of results, with no items.
this.TotalPages = 1;
this.FirstItemNumber = 0;
this.LastItemNumber = 0;
this.ItemCount = 0;
this.IsFirstPage = true;
this.IsLastPage = true;
this.PreviousPage = PageNumberAndSize.Empty;
this.NextPage = PageNumberAndSize.Empty;
this.FirstPage = this.CurrentPage;
this.LastPage = this.CurrentPage;
}
}
this.AllPages = this.IncludeAllPagesAndItemNumbers
? AllPagesAndItemNumbers(this.CurrentPage.Size, this.TotalItems, this.TotalPages)
: null;
}
public void ReturnsEmptyFromEmpty()
{
PageNumberAndSize newPage = PagingInfo.Empty.TurnToPage(6);
PageNumberAndSizeTests.AssertIsEmpty(newPage);
}
