#96 support custom collation.

Author: Marc Sallin

SQLite.CodeFirst/Internal/Builder/ColumnStatementCollectionBuilder.cs

@@ -78,7 +78,7 @@ private static void AddCollationConstraintIfNecessary(EdmProperty property, Colu
             var value = property.GetCustomAnnotation<CollateAttribute>();
             if (value != null)
             {
-                columnStatement.ColumnConstraints.Add(new CollateConstraint { CollationFunction = value.Collation });
+                columnStatement.ColumnConstraints.Add(new CollateConstraint { CollationFunction = value.Collation, CustomCollationFunction = value.Function });
             }
         }
 

SQLite.CodeFirst/Internal/Statement/ColumnConstraint/CollateConstraint.cs

@@ -8,6 +8,8 @@ internal class CollateConstraint : IColumnConstraint
 
         public CollationFunction CollationFunction { get; set; }
 
+        public string CustomCollationFunction { get; set; }
+
         public string CreateStatement()
         {
             if (CollationFunction == CollationFunction.None)
@@ -17,8 +19,9 @@ public string CreateStatement()
 
             var sb = new StringBuilder(Template);
 
-            sb.Replace("{collation-name}", CollationFunction.ToString().ToUpperInvariant());
-
+            string name = CollationFunction == CollationFunction.Custom ? CustomCollationFunction : CollationFunction.ToString().ToUpperInvariant();
+            sb.Replace("{collation-name}", name);
+            
             return sb.ToString().Trim();
         }
     }

SQLite.CodeFirst/Public/Attributes/CollateAttribute.cs

@@ -5,6 +5,7 @@ namespace SQLite.CodeFirst
     /// <summary>
     /// When SQLite compares two strings, it uses a collating sequence or collating function (two words for the same thing)
     /// to determine which string is greater or if the two strings are equal. SQLite has three built-in collating functions (see <see cref="CollationFunction"/>).
+    /// It is possible to specify a custom collating function. Set  <see cref="CollationFunction"/> to <see cref="CollationFunction.Custom"/> and specify the name using the function parameter.
     /// </summary>
     [AttributeUsage(AttributeTargets.Property)]
     public sealed class CollateAttribute : Attribute
@@ -16,9 +17,34 @@ public CollateAttribute()
 
         public CollateAttribute(CollationFunction collation)
         {
+            if (collation == CollationFunction.Custom)
+            {
+                throw new ArgumentException("If the collation is set to CollationFunction.Custom a function must be specified.", nameof(collation));
+            }
+
             Collation = collation;
         }
+        public CollateAttribute(CollationFunction collation, string function)
+        {
+            if (collation != CollationFunction.Custom && !string.IsNullOrEmpty(function))
+            {
+                throw new ArgumentException("If the collation is not set to CollationFunction.Custom a function must not be specified.", nameof(function));
+            }
+
+            if (collation == CollationFunction.Custom && string.IsNullOrEmpty(function))
+            {
+                throw new ArgumentException("If the collation is set to CollationFunction.Custom a function must be specified.", nameof(function));
+            }
+
+            Collation = collation;
+            Function = function;
+        }
+
+        public CollationFunction Collation { get; }
 
-        public CollationFunction Collation { get; private set; }
+        /// <summary>
+        /// The name of the custom collating function to use (CollationFunction.Custom).
+        /// </summary>
+        public string Function { get; }
     }
 }

SQLite.CodeFirst/Public/Attributes/CollationFunction.cs

@@ -9,8 +9,8 @@ public enum CollationFunction
         None,
 
         /// <summary>
-        /// Compares string data using memcmp(), regardless of text encoding.
-        /// </summary>
+        /// The same as binary, except that trailing space characters are ignored.
+        /// </summary>        
         RTrim,
 
         /// <summary>
@@ -21,8 +21,13 @@ public enum CollationFunction
         NoCase,
 
         /// <summary>
-        /// The same as binary, except that trailing space characters are ignored.
+        /// Compares string data using memcmp(), regardless of text encoding.
+        /// </summary>
+        Binary,
+
+        /// <summary>
+        /// An application can register additional collating functions using the sqlite3_create_collation() interface.
         /// </summary>
-        Binary
+        Custom
     }
 }