Multiple db support for REST scenario

src/Config/ObjectModel/RuntimeConfig.cs

@@ -1,6 +1,7 @@
 // Copyright (c) Microsoft Corporation.
 // Licensed under the MIT License.
 
+using System.Diagnostics.CodeAnalysis;
 using System.IO.Abstractions;
 using System.Net;
 using System.Text.Json;
@@ -135,7 +136,9 @@ public bool AllowIntrospection
 
     private Dictionary<string, DataSource> _dataSourceNameToDataSource;
 
-    private Dictionary<string, string> _entityNameToDataSourceName;
+    private Dictionary<string, string> _entityNameToDataSourceName = new();
+
+    private Dictionary<string, string> _entityPathNameToEntityName = new();
 
     /// <summary>
     /// List of all datasources.
@@ -154,6 +157,16 @@ public IEnumerable<DataSource> ListAllDataSources()
         return _dataSourceNameToDataSource.AsEnumerable();
     }
 
+    public bool TryAddEntityPathNameToEntityName(string entityPathName, string entityName)
+    {
+        return _entityPathNameToEntityName.TryAdd(entityPathName, entityName);
+    }
+
+    public bool TryGetEntityNameFromPath(string entityPathName, [NotNullWhen(true)] out string? entityName)
+    {
+        return _entityPathNameToEntityName.TryGetValue(entityPathName, out entityName);
+    }
+
     /// <summary>
     /// Constructor for runtimeConfig.
     /// To be used when setting up from cli json scenario.

src/Core/Resolvers/SqlQueryEngine.cs

@@ -177,8 +177,7 @@ public class SqlQueryEngine : IQueryEngine
         // </summary>
         public async Task<JsonDocument?> ExecuteAsync(FindRequestContext context)
         {
-            // for REST API scenarios, use the default datasource
-            string dataSourceName = _runtimeConfigProvider.GetConfig().DefaultDataSourceName;
+            string dataSourceName = _runtimeConfigProvider.GetConfig().GetDataSourceNameFromEntityName(context.EntityName);
 
             ISqlMetadataProvider sqlMetadataProvider = _sqlMetadataProviderFactory.GetMetadataProvider(dataSourceName);
             SqlQueryStructure structure = new(

src/Core/Services/MetadataProviders/ISqlMetadataProvider.cs

@@ -111,15 +111,6 @@ public interface ISqlMetadataProvider
         /// <returns>True if exists, false otherwise.</returns>
         bool TryGetBackingColumn(string entityName, string field, [NotNullWhen(true)] out string? name);
 
-        /// <summary>
-        /// Try to obtain the name of the Entity that has the provided Path. If It
-        /// exists save in out param, and return true, otherwise return false.
-        /// </summary>
-        /// <param name="entityPathName">Entity's path as seen in a request.</param>
-        /// <param name="entityName">Name of the associated entity.</param>
-        /// <returns>True if exists, otherwise false.</returns>
-        bool TryGetEntityNameFromPath(string entityPathName, [NotNullWhen(true)] out string? entityName);
-
         /// <summary>
         /// Obtains the underlying database type.
         /// </summary>

src/Core/Services/MetadataProviders/SqlMetadataProvider.cs

@@ -69,8 +69,6 @@ public abstract class SqlMetadataProvider<ConnectionT, DataAdapterT, CommandT> :
 
         private Dictionary<string, Dictionary<string, string>> EntityExposedNamesToBackingColumnNames { get; } = new();
 
-        private Dictionary<string, string> EntityPathToEntityName { get; } = new();
-
         protected IAbstractQueryManagerFactory QueryManagerFactory { get; init; }
 
         /// <summary>
@@ -220,12 +218,6 @@ public bool TryGetBackingColumn(string entityName, string field, [NotNullWhen(tr
             return EntityExposedNamesToBackingColumnNames[entityName].TryGetValue(field, out name);
         }
 
-        /// <inheritdoc />
-        public virtual bool TryGetEntityNameFromPath(string entityPathName, [NotNullWhen(true)] out string? entityName)
-        {
-            return EntityPathToEntityName.TryGetValue(entityPathName, out entityName);
-        }
-
         /// <inheritdoc />
         public IReadOnlyDictionary<string, DatabaseObject> GetEntityNamesAndDbObjects()
         {
@@ -503,7 +495,8 @@ private void GenerateRestPathToEntityMap()
 
                     if (!string.IsNullOrEmpty(path))
                     {
-                        EntityPathToEntityName[path] = entityName;
+                        // add the entity path name to the entity name mapping to the runtime config for multi-db resolution.
+                        runtimeConfig.TryAddEntityPathNameToEntityName(path, entityName);
                     }
                 }
                 catch (Exception e)

src/Core/Services/RestService.cs

@@ -212,17 +212,18 @@ RequestValidator requestValidator
         private async Task<IActionResult> DispatchQuery(RestRequestContext context, DatabaseType databaseType)
         {
             IQueryEngine queryEngine = _queryEngineFactory.GetQueryEngine(databaseType);
-            string defaultDataSourceName = _runtimeConfigProvider.GetConfig().DefaultDataSourceName;
+
+            string dataSourceName = _runtimeConfigProvider.GetConfig().GetDataSourceNameFromEntityName(context.EntityName);
 
             if (context is FindRequestContext findRequestContext)
             {
                 using JsonDocument? restApiResponse = await queryEngine.ExecuteAsync(findRequestContext);
-                return restApiResponse is null ? SqlResponseHelpers.FormatFindResult(JsonDocument.Parse("[]").RootElement.Clone(), findRequestContext, _sqlMetadataProviderFactory.GetMetadataProvider(defaultDataSourceName), _runtimeConfigProvider.GetConfig(), GetHttpContext())
-                                               : SqlResponseHelpers.FormatFindResult(restApiResponse.RootElement.Clone(), findRequestContext, _sqlMetadataProviderFactory.GetMetadataProvider(defaultDataSourceName), _runtimeConfigProvider.GetConfig(), GetHttpContext());
+                return restApiResponse is null ? SqlResponseHelpers.FormatFindResult(JsonDocument.Parse("[]").RootElement.Clone(), findRequestContext, _sqlMetadataProviderFactory.GetMetadataProvider(dataSourceName), _runtimeConfigProvider.GetConfig(), GetHttpContext())
+                                               : SqlResponseHelpers.FormatFindResult(restApiResponse.RootElement.Clone(), findRequestContext, _sqlMetadataProviderFactory.GetMetadataProvider(dataSourceName), _runtimeConfigProvider.GetConfig(), GetHttpContext());
             }
             else if (context is StoredProcedureRequestContext storedProcedureRequestContext)
             {
-                return await queryEngine.ExecuteAsync(storedProcedureRequestContext, defaultDataSourceName);
+                return await queryEngine.ExecuteAsync(storedProcedureRequestContext, dataSourceName);
             }
             else
             {
@@ -237,10 +238,10 @@ private async Task<IActionResult> DispatchQuery(RestRequestContext context, Data
         private Task<IActionResult?> DispatchMutation(RestRequestContext context, DatabaseType databaseType)
         {
             IMutationEngine mutationEngine = _mutationEngineFactory.GetMutationEngine(databaseType);
-            string defaultDataSourceName = _runtimeConfigProvider.GetConfig().DefaultDataSourceName;
+            string dataSourceName = _runtimeConfigProvider.GetConfig().GetDataSourceNameFromEntityName(context.EntityName);
             return context switch
             {
-                StoredProcedureRequestContext => mutationEngine.ExecuteAsync((StoredProcedureRequestContext)context, defaultDataSourceName),
+                StoredProcedureRequestContext => mutationEngine.ExecuteAsync((StoredProcedureRequestContext)context, dataSourceName),
                 _ => mutationEngine.ExecuteAsync(context)
             };
         }
@@ -437,8 +438,7 @@ public bool TryGetRestRouteFromConfig([NotNullWhen(true)] out string? configured
         public (string, string) GetEntityNameAndPrimaryKeyRouteFromRoute(string routeAfterPathBase)
         {
 
-            string dataSourceName = _runtimeConfigProvider.GetConfig().DefaultDataSourceName;
-            ISqlMetadataProvider sqlMetadataProvider = _sqlMetadataProviderFactory.GetMetadataProvider(dataSourceName);
+            RuntimeConfig runtimeConfig = _runtimeConfigProvider.GetConfig();
 
             // Split routeAfterPath on the first occurrence of '/', if we get back 2 elements
             // this means we have a non empty primary key route which we save. Otherwise, save
@@ -451,15 +451,15 @@ public bool TryGetRestRouteFromConfig([NotNullWhen(true)] out string? configured
             string entityPath = entityPathAndPKRoute[0];
             string primaryKeyRoute = entityPathAndPKRoute.Length == maxNumberOfElementsFromSplit ? entityPathAndPKRoute[1] : string.Empty;
 
-            if (!sqlMetadataProvider.TryGetEntityNameFromPath(entityPath, out string? entityName))
+            if (!runtimeConfig.TryGetEntityNameFromPath(entityPath, out string? entityName))
             {
                 throw new DataApiBuilderException(
                     message: $"Invalid Entity path: {entityPath}.",
                     statusCode: HttpStatusCode.NotFound,
                     subStatusCode: DataApiBuilderException.SubStatusCodes.EntityNotFound);
             }
 
-            return (entityName, primaryKeyRoute);
+            return (entityName!, primaryKeyRoute);
         }
 
         /// <summary>