Exposing the IgnoreIndex() functionality to the public configuation A…

…PI. Closes GH-2247

src/DocumentDbTests/Configuration/ignoring_indexes_on_document_table.cs

@@ -0,0 +1,37 @@
+using System.Linq;
+using Marten;
+using Marten.Schema;
+using Marten.Storage;
+using Marten.Testing.Documents;
+using Marten.Testing.Harness;
+using Shouldly;
+using Xunit;
+
+namespace DocumentDbTests.Configuration
+{
+    public class ignoring_indexes_on_document_table : OneOffConfigurationsContext
+    {
+        [Fact]
+        public void index_is_ignored_on_document_table()
+        {
+            var mapping = DocumentMapping.For<User>();
+            mapping.IgnoreIndex("foo");
+
+            var table = new DocumentTable(mapping);
+            table.IgnoredIndexes.Any(x => x == "foo").ShouldBeTrue();
+        }
+
+        [Fact]
+        public void ignore_index_through_configuration()
+        {
+            var store = DocumentStore.For(opts =>
+            {
+                opts.Connection(ConnectionSource.ConnectionString);
+                opts.Schema.For<User>().IgnoreIndex("foo");
+            });
+
+            var mapping = store.Options.Storage.MappingFor(typeof(User));
+            new DocumentTable(mapping).IgnoredIndexes.Single().ShouldBe("foo");
+        }
+    }
+}

src/Marten/MartenRegistry.cs

@@ -110,6 +110,18 @@ internal DocumentMappingExpression(DocumentMappingBuilder<T> builder)
                 _builder = builder;
             }
 
+            /// <summary>
+            /// Direct the schema migration detection to ignore the presence of the
+            /// named index on the document storage table
+            /// </summary>
+            /// <param name="indexName"></param>
+            /// <returns></returns>
+            public DocumentMappingExpression<T> IgnoreIndex(string indexName)
+            {
+                _builder.Alter = m => m.IgnoreIndex(indexName);
+                return this;
+            }
+
             /// <summary>
             ///     Specify the property searching mechanism for this document type. The default is
             ///     JSON_Locator_Only