(GH-361) More robust 'Link' parser

Source/StrongGrid/Extensions/Internal.cs

@@ -280,10 +280,12 @@ internal static Task<PaginatedResponseWithLinks<T>> AsPaginatedResponseWithLinks
  var link = response.Message.Headers.GetValue("Link");
  if (string.IsNullOrEmpty(link))
  {
- throw new Exception("The 'Link' header is missing form the response");
+ throw new Exception("The 'Link' header is missing from the response");
  }
 
- return response.Message.Content.AsPaginatedResponseWithLinks<T>(link, propertyName, jsonConverter);
+ var paginationLinks = PaginationLinksParser.Parse(link);
+
+ return response.Message.Content.AsPaginatedResponseWithLinks<T>(paginationLinks, propertyName, jsonConverter);
  }
 
  /// <summary>Asynchronously retrieve the JSON encoded content and convert it to a 'AsPaginatedResponseWithLinks' object.</summary>
@@ -1021,12 +1023,12 @@ private static async Task<PaginatedResponse<T>> AsPaginatedResponse<T>(this Http
  /// <summary>Asynchronously retrieve the JSON encoded content and convert it to a 'PaginatedResponseWithLinks' object.</summary>
  /// <typeparam name="T">The response model to deserialize into.</typeparam>
  /// <param name="httpContent">The content.</param>
- /// <param name="linkHeaderValue">The content of the 'Link' header.</param>
+ /// <param name="paginationLinks">The pagination links.</param>
  /// <param name="propertyName">The name of the JSON property (or null if not applicable) where the desired data is stored.</param>
  /// <param name="jsonConverter">Converter that will be used during deserialization.</param>
  /// <returns>Returns the response body, or <c>null</c> if the response has no body.</returns>
  /// <exception cref="SendGridException">An error occurred processing the response.</exception>
- private static async Task<PaginatedResponseWithLinks<T>> AsPaginatedResponseWithLinks<T>(this HttpContent httpContent, string linkHeaderValue, string propertyName, JsonConverter jsonConverter = null)
+ private static async Task<PaginatedResponseWithLinks<T>> AsPaginatedResponseWithLinks<T>(this HttpContent httpContent, IEnumerable<PaginationLink> paginationLinks, string propertyName, JsonConverter jsonConverter = null)
  {
  var responseContent = await httpContent.ReadAsStringAsync(null).ConfigureAwait(false);
 
@@ -1051,38 +1053,12 @@ private static async Task<PaginatedResponseWithLinks<T>> AsPaginatedResponseWith
  records = JArray.Parse(responseContent).ToObject<T[]>(serializer);
  }
 
- var links = linkHeaderValue
- .Split(new[] { ',' }, StringSplitOptions.RemoveEmptyEntries)
- .Select(link => link.Split(new[] { ';' }, StringSplitOptions.RemoveEmptyEntries))
- .Select(linkParts =>
- {
- var link = linkParts[0]
- .Trim()
- .TrimStart(new[] { '<' })
- .TrimEnd(new[] { '>' });
-
- var rel = linkParts[1]
- .Split(new[] { '=' }, StringSplitOptions.RemoveEmptyEntries)[1]
- .Trim(new[] { ' ', '"' });
-
- var pageNum = linkParts[2]
- .Split(new[] { '=' }, StringSplitOptions.RemoveEmptyEntries)[1]
- .Trim(new[] { ' ', '"' });
-
- return new PaginationLink()
- {
- Link = link,
- Rel = rel,
- PageNumber = int.Parse(pageNum)
- };
- });
-
  var result = new PaginatedResponseWithLinks<T>()
  {
- First = links.Single(l => l.Rel == "first"),
- Previous = links.Single(l => l.Rel == "prev"),
- Next = links.Single(l => l.Rel == "next"),
- Last = links.Single(l => l.Rel == "last"),
+ First = paginationLinks.SingleOrDefault(l => l.Relationship == "first"),
+ Previous = paginationLinks.SingleOrDefault(l => l.Relationship == "prev"),
+ Next = paginationLinks.SingleOrDefault(l => l.Relationship == "next"),
+ Last = paginationLinks.SingleOrDefault(l => l.Relationship == "last"),
  Records = records
  };
 

Source/StrongGrid/Models/PaginationLink.cs

@@ -1,3 +1,6 @@
+using System;
+using System.Collections.Generic;
+
 namespace StrongGrid.Models
 {
  /// <summary>
@@ -6,21 +9,36 @@ namespace StrongGrid.Models
  public class PaginationLink
  {
  /// <summary>
- /// Gets or sets the uri to the page.
+ /// Gets or sets the uri.
  /// </summary>
- public string Link { get; set; }
+ public Uri Link { get; set; }
 
  /// <summary>
- /// Gets or sets the value describing the pagination link.
+ /// Gets or sets the relationship.
+ /// </summary>
+ public string Relationship { get; set; }
+
+ /// <summary>
+ /// Gets or sets the relationship.
  /// </summary>
  /// <remarks>
- /// There are 4 possible values: first, prev, next and last.
+ /// 'Rev' is obviously short for something but I can't figure out what it stands for????
  /// </remarks>
- public string Rel { get; set; }
+ public string Rev { get; set; }
+
+ /// <summary>
+ /// Gets or sets the title.
+ /// </summary>
+ public string Title { get; set; }
+
+ /// <summary>
+ /// Gets or sets the anchor.
+ /// </summary>
+ public Uri Anchor { get; set; }
 
  /// <summary>
- /// Gets or sets the page number.
+ /// Gets or sets the extensions.
  /// </summary>
- public int PageNumber { get; set; }
+ public IEnumerable<KeyValuePair<string, string>> Extensions { get; set; }
  }
 }

Source/StrongGrid/Utilities/PaginationLinksParser.cs

@@ -0,0 +1,64 @@
+using StrongGrid.Models;
+using System;
+using System.Collections.Generic;
+using System.Linq;
+
+namespace StrongGrid.Utilities
+{
+ /// <summary>
+ /// Parser for pagination links.
+ /// </summary>
+ /// <remarks>
+ /// This parser attempts to respect the HTTP 1.1 'Link' rules defined in <see cref="https://tools.ietf.org/html/rfc2068#section-19.6.2.4">RFC 2068</see>.
+ /// </remarks>
+ public static class PaginationLinksParser
+ {
+ private static readonly string[] _wellKnownLinkParts = new[] { "rel", "rev", "title", "anchor" };
+
+ /// <summary>
+ /// Parse the content of the link response header.
+ /// </summary>
+ /// <param name="linkHeaderContent">The content of the link header.</param>
+ /// <returns>An array of <see cref="PaginationLink"/>.</returns>
+ public static PaginationLink[] Parse(string linkHeaderContent)
+ {
+ var paginationLinks = linkHeaderContent
+ .Split(new[] { ',' }, StringSplitOptions.RemoveEmptyEntries)
+ .Select(link => link.Split(new[] { ';' }, StringSplitOptions.RemoveEmptyEntries))
+ .Select(linkParts =>
+ {
+ var dict = new Dictionary<string, string>();
+ foreach (var linkPart in linkParts.Skip(1))
+ {
+ var parts = linkPart.Split(new[] { '=' }, StringSplitOptions.RemoveEmptyEntries);
+ var partName = parts[0].Trim();
+ var partValue = parts[1].Trim(new[] { ' ', '"' });
+
+ dict.Add(partName, partValue);
+ }
+
+ var link = linkParts[0].Trim().TrimStart(new[] { '<' }).TrimEnd(new[] { '>' }).Trim();
+ dict.TryGetValue("rel", out string rel);
+ dict.TryGetValue("rev", out string rev);
+ dict.TryGetValue("title", out string title);
+ dict.TryGetValue("anchor", out string anchor);
+
+ var extensions = dict
+ .Where(item => !_wellKnownLinkParts.Contains(item.Key))
+ .ToArray();
+
+ return new PaginationLink()
+ {
+ Link = !string.IsNullOrEmpty(link) ? new Uri(link) : null,
+ Relationship = rel,
+ Rev = rev,
+ Title = title,
+ Anchor = !string.IsNullOrEmpty(anchor) ? new Uri(anchor) : null,
+ Extensions = extensions
+ };
+ });
+
+ return paginationLinks.ToArray();
+ }
+ }
+}