Add go backing store support.

CHANGELOG.md

@@ -10,10 +10,11 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ### Added
 
 - Added support for external documentation links on request execution methods (PHP Generation). [2038](https://github.com/microsoft/kiota/issues/2138)
-- Adds support for nullable reference types in dotnet for projects running Netstandard 2.1/Net 6.0 and above []()
+- Added support for nullable reference types in dotnet for projects running Netstandard 2.1/Net 6.0 and above [2073](https://github.com/microsoft/kiota/issues/2073)
 - Added support for multi-value headers to CLI generation. (Shell)
-- Add support for multi-value headers for PHP Generation. [#2052](https://github.com/microsoft/kiota/issues/2052)
-- Add support for Composed types (De)Serialization for PHP Generation. [#1814](https://github.com/microsoft/kiota/issues/1814)
+- Added support for multi-value headers for PHP Generation. [#2052](https://github.com/microsoft/kiota/issues/2052)
+- Added support for Composed types (De)Serialization for PHP Generation. [#1814](https://github.com/microsoft/kiota/issues/1814)
+- Added support for backing store in Go. [466](https://github.com/microsoft/kiota/issues/466)
 
 ### Changed
 

src/Kiota.Builder/KiotaBuilder.cs

@@ -1351,7 +1351,7 @@ private void CreatePropertiesForModelClass(OpenApiUrlTreeNode currentNode, OpenA
     private const string AdditionalDataPropName = "AdditionalData";
     private const string BackingStorePropertyName = "BackingStore";
     private const string BackingStoreInterface = "IBackingStore";
-    private const string BackedModelInterface = "IBackedModel";
+    internal const string BackedModelInterface = "IBackedModel";
     private const string ParseNodeInterface = "IParseNode";
     internal const string AdditionalHolderInterface = "IAdditionalDataHolder";
     internal static void AddSerializationMembers(CodeClass model, bool includeAdditionalProperties, bool usesBackingStore) {

src/Kiota.Builder/Refiners/CommonLanguageRefiner.cs

@@ -68,18 +68,21 @@ private static bool ReplaceSerializationModules(CodeElement generatedCode, Func<
 
         return false;
     }
-    protected static void CorrectCoreTypesForBackingStore(CodeElement currentElement, string defaultPropertyValue) {
+    protected static void CorrectCoreTypesForBackingStore(CodeElement currentElement, string defaultPropertyValue, Boolean hasPrefix = true) {
         if(currentElement is CodeClass currentClass && currentClass.IsOfKind(CodeClassKind.Model, CodeClassKind.RequestBuilder)
             && currentClass.StartBlock is ClassDeclaration currentDeclaration) {
             var backedModelImplements = currentDeclaration.Implements.FirstOrDefault(x => "IBackedModel".Equals(x.Name, StringComparison.OrdinalIgnoreCase));
             if(backedModelImplements != null)
                 backedModelImplements.Name = backedModelImplements.Name[1..]; //removing the "I"
             var backingStoreProperty = currentClass.GetPropertyOfKind(CodePropertyKind.BackingStore);
-            if(backingStoreProperty != null)
+            if (backingStoreProperty != null)
+            {
                 backingStoreProperty.DefaultValue = defaultPropertyValue;
+                backingStoreProperty.NamePrefix = hasPrefix ? backingStoreProperty.NamePrefix : String.Empty;
+            }
 
         }
-        CrawlTree(currentElement, x => CorrectCoreTypesForBackingStore(x, defaultPropertyValue));
+        CrawlTree(currentElement, x => CorrectCoreTypesForBackingStore(x, defaultPropertyValue, hasPrefix));
     }
     private static bool DoesAnyParentHaveAPropertyWithDefaultValue(CodeClass current)
     {

src/Kiota.Builder/Refiners/GoRefiner.cs

@@ -3,6 +3,7 @@
 using System.Linq;
 using System.Threading;
 using System.Threading.Tasks;
+using System.Xml.Linq;
 using Kiota.Builder.CodeDOM;
 using Kiota.Builder.Configuration;
 using Kiota.Builder.Extensions;
@@ -139,6 +140,8 @@ public override Task Refine(CodeNamespace generatedCode, CancellationToken cance
             RemoveHandlerFromRequestBuilder(generatedCode);
             AddContextParameterToGeneratorMethods(generatedCode);
             CorrectTypes(generatedCode);
+            CorrectCoreTypesForBackingStore(generatedCode, $"{conventions.StoreHash}.BackingStoreFactoryInstance()", false);
+            CorrectBackingStoreTypes(generatedCode);
         }, cancellationToken);
     }
 
@@ -154,6 +157,59 @@ private string MergeOverLappedStrings(string start, string end)
 
         return $"{start}{end}";
     }
+
+    private void CorrectBackingStoreTypes(CodeElement currentElement, Dictionary<String, CodeInterface> result = null)
+    {
+        if (!_configuration.UsesBackingStore)
+            return;
+
+        var currentMethod = currentElement as CodeMethod;
+        var parameters = currentMethod?.Parameters;
+        var codeParameters = parameters as CodeParameter[] ?? parameters?.ToArray();
+        codeParameters?.Where(x => x.IsOfKind(CodeParameterKind.BackingStore)
+                                   && currentMethod.IsOfKind(CodeMethodKind.ClientConstructor)).ToList().ForEach(x =>
+        {
+            var type = (x.Type as CodeType)!;
+            type.Name = "BackingStoreFactory";
+            type.IsNullable = false;
+            type.IsExternal = true;
+        });
+
+        if (currentElement is CodeClass codeClass && codeClass.IsOfKind(CodeClassKind.Model))
+        {
+            var propertiesToCorrect = codeClass.Properties
+                .Where(x => x.IsOfKind(CodePropertyKind.Custom))
+                .Union(codeClass.Methods
+                    .Where(x => x.IsAccessor && (x.AccessedProperty?.IsOfKind(CodePropertyKind.Custom) ?? false))
+                    .Select(static x => x.AccessedProperty))
+                .Distinct()
+                .OrderBy(static x => x.Name, StringComparer.OrdinalIgnoreCase);
+
+            var targetNameSpace = codeClass.GetImmediateParentOfType<CodeNamespace>();
+            var modelsNameSpace = findClientNameSpace(targetNameSpace)
+                .FindNamespaceByName($"{_configuration.ClientNamespaceName}.models");
+
+            foreach (var property in propertiesToCorrect)
+            {
+                if (property.Type is CodeType codeType && codeType.TypeDefinition is CodeClass)
+                {
+                    var interfaceName = $"{codeType.Name}able";
+                    var existing = targetNameSpace.FindChildByName<CodeInterface>(interfaceName, false) ??
+                                   modelsNameSpace.FindChildByName<CodeInterface>(interfaceName) ??
+                                   modelsNameSpace.FindChildByName<CodeInterface>(interfaceName.ToFirstCharacterUpperCase());
+
+                    if (existing == null)
+                        continue;
+
+                    CodeType type = (codeType.Clone() as CodeType)!;
+                    type.Name = interfaceName;
+                    type.TypeDefinition = existing;
+                    property.Type = type;
+                }
+            }
+        }
+        CrawlTree(currentElement, x => CorrectBackingStoreTypes(x, result));
+    }
 
     private static void CorrectTypes(CodeElement currentElement)
     {
@@ -414,9 +470,15 @@ x.Type is CodeType pType &&
             "github.com/microsoft/kiota-abstractions-go/serialization", "MergeDeserializersForIntersectionWrapper"),
         new (static x => x is CodeProperty prop && prop.IsOfKind(CodePropertyKind.Headers),
             "github.com/microsoft/kiota-abstractions-go", "RequestHeaders"),
-    };//TODO add backing store types once we have them defined
-    private static void CorrectImplements(ProprietableBlockDeclaration block) {
+        new (static x => x is CodeProperty prop && prop.IsOfKind(CodePropertyKind.BackingStore), "github.com/microsoft/kiota-abstractions-go/store","BackingStore"),
+        new (static x => x is CodeMethod method && method.IsOfKind(CodeMethodKind.ClientConstructor) &&
+                         method.Parameters.Any(y => y.IsOfKind(CodeParameterKind.BackingStore)),
+            "github.com/microsoft/kiota-abstractions-go/store", "BackingStoreFactory"),
+    };
+
+    private void CorrectImplements(ProprietableBlockDeclaration block) {
         block.ReplaceImplementByName(KiotaBuilder.AdditionalHolderInterface, "AdditionalDataHolder");
+        block.ReplaceImplementByName(KiotaBuilder.BackedModelInterface, "BackedModel");
     }
     private static void CorrectMethodType(CodeMethod currentMethod) {
         var parentClass = currentMethod.Parent as CodeClass;

src/Kiota.Builder/Writers/Go/CodeMethodWriter.cs

@@ -381,15 +381,26 @@ private void WriteGetterBody(CodeMethod codeElement, LanguageWriter writer, Code
                 if(!(codeElement.AccessedProperty?.Type?.IsNullable ?? true) &&
                    !(codeElement.AccessedProperty?.ReadOnly ?? true) &&
                     !string.IsNullOrEmpty(codeElement.AccessedProperty?.DefaultValue)) {
-                    writer.WriteLines($"{conventions.GetTypeString(codeElement.AccessedProperty.Type, parentClass)} value = m.{backingStore.NamePrefix}{backingStore.Name.ToFirstCharacterLowerCase()}.Get(\"{codeElement.AccessedProperty.Name.ToFirstCharacterLowerCase()}\")",
-                        "if value == nil {");
-                    writer.IncreaseIndent();
-                    writer.WriteLines($"value = {codeElement.AccessedProperty.DefaultValue};",
+                    writer.WriteLines(
+                        $"val , err :=  m.{backingStore.NamePrefix}{backingStore.Name.ToFirstCharacterLowerCase()}.Get(\"{codeElement.AccessedProperty.Name.ToFirstCharacterLowerCase()}\")");
+                    writer.WriteBlock("if err != nil {", "}", "panic(err)");
+                    writer.WriteBlock("if val == nil {" , "}", 
+                        $"var value = {codeElement.AccessedProperty.DefaultValue};",
                         $"m.Set{codeElement.AccessedProperty?.Name?.ToFirstCharacterUpperCase()}(value);");
-                    writer.CloseBlock();
-                    writer.WriteLine("return value;");
-                } else
-                    writer.WriteLine($"return m.Get{backingStore.Name.ToFirstCharacterUpperCase()}().Get(\"{codeElement.AccessedProperty?.Name?.ToFirstCharacterLowerCase()}\");");
+
+                    writer.WriteLine($"return val.({conventions.GetTypeString(codeElement.AccessedProperty.Type, parentClass)})");
+                }
+                else
+                {
+                    var returnType = conventions.GetTypeString(codeElement.ReturnType, codeElement.Parent);
+
+                    writer.WriteLine($"val , err := m.Get{backingStore.Name.ToFirstCharacterUpperCase()}().Get(\"{codeElement.AccessedProperty?.Name?.ToFirstCharacterLowerCase()}\")");
+
+                    writer.WriteBlock("if val != nil {", "}", $"return val.({returnType})");
+                    writer.WriteBlock("if err != nil {", "}", "panic(err)");
+
+                    writer.WriteLine("return nil");
+                }
         }
         private void WriteApiConstructorBody(CodeClass parentClass, CodeMethod method, LanguageWriter writer) {
             var requestAdapterProperty = parentClass.GetPropertyOfKind(CodePropertyKind.RequestAdapter);
@@ -483,7 +494,10 @@ private static void WriteSetterBody(CodeMethod codeElement, LanguageWriter write
             if(backingStore == null)
                 writer.WriteLine($"m.{codeElement.AccessedProperty?.Name?.ToFirstCharacterLowerCase()} = value");
             else
-                writer.WriteLine($"m.Get{backingStore.Name.ToFirstCharacterUpperCase()}().Set(\"{codeElement.AccessedProperty?.Name?.ToFirstCharacterLowerCase()}\", value)");
+            {
+                writer.WriteLine($"err := m.Get{backingStore.Name.ToFirstCharacterUpperCase()}().Set(\"{codeElement.AccessedProperty?.Name?.ToFirstCharacterLowerCase()}\", value)");
+                writer.WriteBlock("if err != nil {", "}", "panic(err)");
+            }
         }
         private void WriteIndexerBody(CodeMethod codeElement, CodeClass parentClass, LanguageWriter writer, string returnType) {
             var pathParametersProperty = parentClass.GetPropertyOfKind(CodePropertyKind.PathParameters);

src/Kiota.Builder/Writers/Go/GoConventionService.cs

@@ -17,6 +17,7 @@ public class GoConventionService : CommonLanguageConventionService
     #pragma warning disable CA1822 // Method should be static
     public string AbstractionsHash => "i2ae4187f7daee263371cb1c977df639813ab50ffa529013b7437480d1ec0158f";
     public string SerializationHash => "i878a80d2330e89d26896388a3f487eef27b0a0e6c010c493bf80be1452208f91";
+    public string StoreHash => "ie8677ce2c7e1b4c22e9c3827ecd078d41185424dd9eeb92b7d971ed2d49a392e";
     public string StringsHash => "ie967d16dae74a49b5e0e051225c5dac0d76e5e38f13dd1628028cbce108c25b6";
 
     public string ContextVarTypeName => "context.Context";
@@ -94,6 +95,7 @@ public string TranslateType(CodeTypeBase type, bool includeImportSymbol)
             "string" or "float32" or "float64" or "int32" or "int64" => type.Name,
             "String" or "Int64" or "Int32" or "Float32" or "Float64" => type.Name.ToFirstCharacterLowerCase(), //casing hack
             "context.Context" => "context.Context",
+            "BackedModel" => $"{StoreHash}.BackedModel",
             _ => type.Name.ToFirstCharacterUpperCase() ?? "Object",
         };
     }

src/Kiota.Builder/Writers/LanguageWriter.cs

@@ -83,6 +83,13 @@ internal void CloseBlock(string symbol = "}", bool decreaseIndent = true)
             WriteLine(symbol);
         }
 
+        internal void WriteBlock(string startSymbol = "{", string closeSymbol = "}", params string[] lines)
+        {
+            StartBlock(startSymbol);
+            WriteLines(lines);
+            CloseBlock(closeSymbol);
+        }
+
         internal void Write(string text, bool includeIndent = true)
         {
             writer.Write(includeIndent ? GetIndent() + text : text);

tests/Kiota.Builder.Tests/Writers/Go/CodeMethodWriterTests.cs

@@ -1330,7 +1330,7 @@ public void WritesGetterToBackingStoreWithNonnullProperty() {
         method.Kind = CodeMethodKind.Getter;
         writer.Write(method);
         var result = tw.ToString();
-        Assert.Contains("if value == nil", result);
+        Assert.Contains("if val == nil", result);
         Assert.Contains(defaultValue, result);
     }
     [Fact]