Interfaces for polymorphic API resources (external accounts and payment sources)

src/Stripe.net/Entities/Accounts/Account.cs

@@ -2,11 +2,10 @@ namespace Stripe
 {
     using System;
     using System.Collections.Generic;
-    using System.Linq;
     using Newtonsoft.Json;
     using Stripe.Infrastructure;
 
-    public class Account : StripeEntity, IHasId, IHasObject
+    public class Account : StripeEntity, IHasId, IHasObject, IPaymentSource
     {
         [JsonProperty("id")]
         public string Id { get; set; }
@@ -73,7 +72,7 @@ internal object InternalBusinessLogo
         public string Email { get; set; }
 
         [JsonProperty("external_accounts")]
-        public StripeList<ExternalAccount> ExternalAccounts { get; set; }
+        public StripeList<IExternalAccount> ExternalAccounts { get; set; }
 
         [JsonProperty("keys")]
         public CustomAccountKeys Keys { get; set; }

src/Stripe.net/Entities/BankAccounts/BankAccount.cs

@@ -5,7 +5,7 @@ namespace Stripe
     using Newtonsoft.Json;
     using Stripe.Infrastructure;
 
-    public class BankAccount : StripeEntity, IHasId, IHasObject
+    public class BankAccount : StripeEntity, IHasId, IHasObject, IExternalAccount, IPaymentSource
     {
         [JsonProperty("id")]
         public string Id { get; set; }

src/Stripe.net/Entities/Cards/Card.cs

@@ -4,7 +4,7 @@ namespace Stripe
     using Newtonsoft.Json;
     using Stripe.Infrastructure;
 
-    public class Card : StripeEntity, IHasId, IHasObject
+    public class Card : StripeEntity, IHasId, IHasObject, IExternalAccount, IPaymentSource
     {
         [JsonProperty("id")]
         public string Id { get; set; }

src/Stripe.net/Entities/Charges/Charge.cs

@@ -337,7 +337,7 @@ internal object InternalReview
         /// For most Stripe users, the source of every charge is a credit or debit card. This hash is then the card object describing that card.
         /// </summary>
         [JsonProperty("source")]
-        public PaymentSource Source { get; set; }
+        public IPaymentSource Source { get; set; }
 
         #region Expandable Transfer
 

src/Stripe.net/Entities/Customers/Customer.cs

@@ -37,14 +37,14 @@ public class Customer : StripeEntity, IHasId, IHasObject
         public string DefaultSourceId { get; set; }
 
         [JsonIgnore]
-        public PaymentSource DefaultSource { get; set; }
+        public IPaymentSource DefaultSource { get; set; }
 
         [JsonProperty("default_source")]
         internal object InternalDefaultSource
         {
             set
             {
-                StringOrObject<PaymentSource>.Map(value, s => this.DefaultSourceId = s, o => this.DefaultSource = o);
+                StringOrObject<IPaymentSource>.Map(value, s => this.DefaultSourceId = s, o => this.DefaultSource = o);
             }
         }
 
@@ -99,7 +99,7 @@ internal object InternalDefaultSource
         /// The customer’s payment sources, if any
         /// </summary>
         [JsonProperty("sources")]
-        public StripeList<PaymentSource> Sources { get; set; }
+        public StripeList<IPaymentSource> Sources { get; set; }
 
         /// <summary>
         /// The customer’s current subscriptions, if any

src/Stripe.net/Entities/PaymentIntents/PaymentIntent.cs

@@ -122,14 +122,14 @@ internal object InternalReview
         public string SourceId { get; set; }
 
         [JsonIgnore]
-        public PaymentSource Source { get; set; }
+        public IPaymentSource Source { get; set; }
 
         [JsonProperty("source")]
         internal object InternalSource
         {
             set
             {
-                StringOrObject<PaymentSource>.Map(value, s => this.SourceId = s, o => this.Source = o);
+                StringOrObject<IPaymentSource>.Map(value, s => this.SourceId = s, o => this.Source = o);
             }
         }
         #endregion

src/Stripe.net/Entities/Payouts/Payout.cs

@@ -51,14 +51,14 @@ internal object InternalBalanceTransaction
         public string DestinationId { get; set; }
 
         [JsonIgnore]
-        public ExternalAccount Destination { get; set; }
+        public IExternalAccount Destination { get; set; }
 
         [JsonProperty("destination")]
         internal object InternalDestination
         {
             set
             {
-                StringOrObject<ExternalAccount>.Map(value, s => this.DestinationId = s, o => this.Destination = o);
+                StringOrObject<IExternalAccount>.Map(value, s => this.DestinationId = s, o => this.Destination = o);
             }
         }
         #endregion

src/Stripe.net/Entities/Sources/Source.cs

@@ -3,12 +3,11 @@ namespace Stripe
     using System;
     using System.Collections.Generic;
     using Newtonsoft.Json;
-    using Stripe.Infrastructure;
 
     /// <summary>
     /// Source objects allow you to accept a variety of payment methods. They represent a customer's payment instrument and can be used with the Source API just like a card object: once chargeable, they can be charged, or attached to customers.
     /// </summary>
-    public class Source : StripeEntity, IHasId, IHasObject
+    public class Source : StripeEntity, IHasId, IHasObject, IPaymentSource
     {
         [JsonProperty("id")]
         public string Id { get; set; }

src/Stripe.net/Entities/_interfaces/IExternalAccount.cs

@@ -0,0 +1,13 @@
+namespace Stripe
+{
+    /// <summary>
+    /// Resources that implement this interface can be used as external accounts, i.e. they can
+    /// be attached to a Stripe account to receive payouts.
+    /// </summary>
+    public interface IExternalAccount : IStripeEntity, IHasId, IHasObject
+    {
+        Account Account { get; set; }
+
+        string AccountId { get; set; }
+    }
+}

src/Stripe.net/Entities/_interfaces/IPaymentSource.cs

@@ -0,0 +1,9 @@
+namespace Stripe
+{
+    /// <summary>
+    /// Resources that implement this interface can be used to create charges.
+    /// </summary>
+    public interface IPaymentSource : IStripeEntity, IHasId, IHasObject
+    {
+    }
+}

src/Stripe.net/Infrastructure/JsonConverters/AbstractStripeObjectConverter.cs

@@ -0,0 +1,51 @@
+namespace Stripe.Infrastructure
+{
+    using System;
+    using System.Collections.Generic;
+    using Newtonsoft.Json;
+    using Newtonsoft.Json.Linq;
+
+    /// <summary>
+    /// This converter is used to deserialize polymorphic resources. The resources must implement
+    /// a common interface.
+    /// </summary>
+    /// <typeparam name="I">interface implemented by all resources that this converter can
+    /// return</typeparam>
+    internal abstract class AbstractStripeObjectConverter<I> : JsonConverter
+        where I : IHasObject
+    {
+        public override bool CanWrite => false;
+
+        /// <summary>
+        /// This is the only property that needs to be declared by concrete converters. It is a
+        /// mapping of object names (e.g. <c>"card"</c>) to mapper functions (e.g.
+        /// <c>Mapper&lt;Card&gt;.FromJson</c>).
+        /// </summary>
+        protected abstract Dictionary<string, Func<string, I>> ObjectsToMapperFuncs { get; }
+
+        public override bool CanConvert(Type objectType)
+        {
+            return objectType == typeof(I);
+        }
+
+        public override void WriteJson(JsonWriter writer, object value, JsonSerializer serializer)
+        {
+            var incoming = JObject.FromObject(value);
+            incoming.WriteTo(writer);
+        }
+
+        public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer)
+        {
+            var incoming = JObject.Load(reader);
+            var obj = default(I);
+            var objectName = incoming.SelectToken("object")?.ToString();
+            if (this.ObjectsToMapperFuncs.ContainsKey(objectName))
+            {
+                var mapperFunc = this.ObjectsToMapperFuncs[objectName];
+                obj = mapperFunc(incoming.ToString());
+            }
+
+            return obj;
+        }
+    }
+}

src/Stripe.net/Infrastructure/JsonConverters/ExternalAccountConverter.cs

@@ -1,47 +1,15 @@
 namespace Stripe.Infrastructure
 {
     using System;
-    using Newtonsoft.Json;
-    using Newtonsoft.Json.Linq;
+    using System.Collections.Generic;
 
-    internal class ExternalAccountConverter : JsonConverter
+    internal class ExternalAccountConverter : AbstractStripeObjectConverter<IExternalAccount>
     {
-        public override bool CanWrite => false;
-
-        public override bool CanConvert(Type objectType)
-        {
-            throw new NotImplementedException();
-        }
-
-        public override void WriteJson(JsonWriter writer, object value, JsonSerializer serializer)
-        {
-            var incoming = JObject.FromObject(value);
-
-            incoming.WriteTo(writer);
-        }
-
-        public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer)
+        protected override Dictionary<string, Func<string, IExternalAccount>> ObjectsToMapperFuncs
+            => new Dictionary<string, Func<string, IExternalAccount>>()
         {
-            var incoming = JObject.Load(reader);
-
-            var externalAccount = new ExternalAccount
-            {
-                Id = incoming.SelectToken("id").ToString()
-            };
-
-            if (incoming.SelectToken("object")?.ToString() == "bank_account")
-            {
-                externalAccount.Type = ExternalAccountType.BankAccount;
-                externalAccount.BankAccount = Mapper<BankAccount>.MapFromJson(incoming.ToString());
-            }
-
-            if (incoming.SelectToken("object")?.ToString() == "card")
-            {
-                externalAccount.Type = ExternalAccountType.Card;
-                externalAccount.Card = Mapper<Card>.MapFromJson(incoming.ToString());
-            }
-
-            return externalAccount;
-        }
+            { "bank_account", Mapper<BankAccount>.MapFromJson },
+            { "card", Mapper<Card>.MapFromJson },
+        };
     }
 }

src/Stripe.net/Infrastructure/JsonConverters/PaymentSourceConverter.cs

@@ -1,59 +1,17 @@
 namespace Stripe.Infrastructure
 {
     using System;
-    using Newtonsoft.Json;
-    using Newtonsoft.Json.Linq;
+    using System.Collections.Generic;
 
-    internal class PaymentSourceConverter : JsonConverter
+    internal class PaymentSourceConverter : AbstractStripeObjectConverter<IPaymentSource>
     {
-        public override bool CanWrite => false;
-
-        public override bool CanConvert(Type objectType)
-        {
-            throw new NotImplementedException();
-        }
-
-        public override void WriteJson(JsonWriter writer, object value, JsonSerializer serializer)
-        {
-            var incoming = JObject.FromObject(value);
-
-            incoming.WriteTo(writer);
-        }
-
-        public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer)
+        protected override Dictionary<string, Func<string, IPaymentSource>> ObjectsToMapperFuncs =>
+            new Dictionary<string, Func<string, IPaymentSource>>()
         {
-            var incoming = JObject.Load(reader);
-
-            var source = new PaymentSource
-            {
-                Id = incoming.SelectToken("id").ToString()
-            };
-
-            if (incoming.SelectToken("object")?.ToString() == "account")
-            {
-                source.Type = PaymentSourceType.Account;
-                source.Account = Mapper<Account>.MapFromJson(incoming.ToString());
-            }
-
-            if (incoming.SelectToken("object")?.ToString() == "bank_account")
-            {
-                source.Type = PaymentSourceType.BankAccount;
-                source.BankAccount = Mapper<BankAccount>.MapFromJson(incoming.ToString());
-            }
-
-            if (incoming.SelectToken("object")?.ToString() == "card")
-            {
-                source.Type = PaymentSourceType.Card;
-                source.Card = Mapper<Card>.MapFromJson(incoming.ToString());
-            }
-
-            if (incoming.SelectToken("object")?.ToString() == "source")
-            {
-                source.Type = PaymentSourceType.Source;
-                source.SourceObject = Mapper<Source>.MapFromJson(incoming.ToString());
-            }
-
-            return source;
-        }
+            { "account", Mapper<Account>.MapFromJson },
+            { "bank_account", Mapper<BankAccount>.MapFromJson },
+            { "card", Mapper<Card>.MapFromJson },
+            { "source", Mapper<Source>.MapFromJson },
+        };
     }
 }