Refactoring

Builders and PArsers converted to static methods.

Author: JocaPC

Controller/RestApiController.cs

@@ -0,0 +1,36 @@
+using Belgrade.SqlClient;
+using SqlServerRestApi.SQL;
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Threading.Tasks;
+
+namespace SqlServerRestApi.Controller
+{
+    public class RestApiController : Microsoft.AspNetCore.Mvc.Controller
+    {
+        IQueryPipe sqlQuery = null;
+        TableSpec tableSpec = null;
+
+        public RestApiController(TableSpec tableSpec, IQueryPipe sqlQueryService)
+        {
+            this.sqlQuery = sqlQueryService;
+            this.tableSpec = tableSpec;
+        }
+
+        public async Task ProcessODataRequest(string defaultOutput)
+        {
+            var querySpec = OData.UriParser.Parse(this.tableSpec, this.Request);
+            var sql = QueryBuilder.Build(querySpec, tableSpec).AsJson();
+            await sqlQuery.Stream(sql, Response.Body, defaultOutput);
+        }
+
+        
+        public async Task ProcessJQueryDataTablesRequest(string defaultOutput)
+        {
+            var querySpec = JQueryDataTable.UriParser.Parse(this.tableSpec, this.Request);
+            var sql = QueryBuilder.Build(querySpec, tableSpec).AsJson();
+            await sqlQuery.Stream(sql, Response.Body, defaultOutput);
+        }
+    }
+}

JQueryDataTables/UriParser.cs

@@ -7,7 +7,7 @@ namespace SqlServerRestApi.JQueryDataTable
 {
     public class UriParser
     {
-        public QuerySpec Parse (TableSpec tabSpec, HttpRequest Request)
+        public static QuerySpec Parse (TableSpec tabSpec, HttpRequest Request)
         {
             var spec = new QuerySpec();
             spec.skip = Convert.ToInt32(Request.Query["start"]);

OData/UriParser.cs

@@ -10,7 +10,7 @@ namespace SqlServerRestApi.OData
 
     public class UriParser
     {
-        public QuerySpec Parse (TableSpec tabSpec, HttpRequest Request)
+        public static QuerySpec Parse (TableSpec tabSpec, HttpRequest Request)
         {
             var spec = new QuerySpec();
             spec.skip = Convert.ToInt32(Request.Query["$skip"]);

README.md

@@ -67,34 +67,30 @@ Note that FOR JSON clause is used in SQL query. FOR JSON clause will generate JS
 
 ## Implement OData service
 
-To implement OData Service, you would need to add the following fields in your controller:
- - TableSpec hat describes the structure of the table that will be queried (name and columns)
- - UriParser that will parse OData Http request and extract information from $select, $filter, $orderby, $top, and $skip parameters
- - QueryBuilder that will create T-SQL query that will be executed. 
-
-Example is shown in the following code:
+To implement OData Service, you would need to add the TableSpec object that describes the structure of the table that will be queried (name and columns). An example is shown in the following code:
 ```
         IQueryPipe sqlQuery = null;
         
         TableSpec tableSpec = new TableSpec("dbo.People", "name,surname,address,town");
-        UriParser uriParser = new UriParser();
-        QueryBuilder queryBuilder = new QueryBuilder();
-
+        
         public PeopleController(IQueryPipe sqlQueryService)
         {
             this.sqlQuery = sqlQueryService;
         }
 ```
 
-Now you need to create async method that will serve OData requests. First, you need to parse Request parameters using UriParser in order to extract QuerySpec. Then you need to use QueryBuilder to create SQL query using the QuerySpec. Then you need to provide sql query to QueryPipe that will stream results to client using Response.Body:
+Now you need to create async method that will serve OData requests with following classes:
+ - UriParser that will parse OData Http request and extract information from $select, $filter, $orderby, $top, and $skip parameters
+ - QueryBuilder that will create T-SQL query that will be executed. 
+First, you need to parse Request parameters using UriParser in order to extract the definition of query (QuerySpec object). Then you need to use QueryBuilder to create SQL query using the QuerySpec. Then you need to provide sql query to QueryPipe that will stream results to client using Response.Body:
 
 ```
        // GET api/People
         [HttpGet]
         public async Task Get()
         {            
-            var querySpec = uriParser.Parse(tableSpec, this.Request);
-            var sql = queryBuilder.Build(querySpec, tableSpec).AsJson();
+            var querySpec = OData.UriParser.Parse(tableSpec, this.Request);
+            var sql = QueryBuilder.Build(querySpec, tableSpec).AsJson();
             await sqlQuery.Stream(sql, Response.Body, "[]");
         }
  ```

SQL/QueryBuilder.cs

@@ -4,23 +4,24 @@
 
 namespace SqlServerRestApi.SQL
 {
-    internal class QueryBuilder
+    public static class QueryBuilder
     {
-        private StringBuilder sql = new StringBuilder();
-        internal SqlCommand Build(QuerySpec spec, TableSpec table)
+        
+        public static SqlCommand Build(QuerySpec spec, TableSpec table)
         {
             SqlCommand res = new SqlCommand();
-            
-            BuildSelectClause(spec, table);
-            BuildWherePredicate(spec, res);
-            BuildOrderByClause(spec);
-            BuildOffsetFetchClause(spec);
+            StringBuilder sql = new StringBuilder();
+
+            BuildSelectClause(spec, table, sql);
+            BuildWherePredicate(spec, res, sql);
+            BuildOrderByClause(spec, sql);
+            BuildOffsetFetchClause(spec, sql);
 
             res.CommandText = sql.ToString();
             return res;
         }
 
-        private void BuildSelectClause(QuerySpec spec, TableSpec table)
+        private static void BuildSelectClause(QuerySpec spec, TableSpec table, StringBuilder sql)
         {
             sql.Append("select ");
 
@@ -39,7 +40,7 @@ private void BuildSelectClause(QuerySpec spec, TableSpec table)
         /// </summary>
         /// <param name="spec"></param>
         /// <param name="res"></param>
-        private void BuildWherePredicate(QuerySpec spec, SqlCommand res)
+        private static void BuildWherePredicate(QuerySpec spec, SqlCommand res, StringBuilder sql)
         {
             if (spec.predicate != null)
             {
@@ -111,7 +112,7 @@ private void BuildWherePredicate(QuerySpec spec, SqlCommand res)
             }
         }
 
-        private void BuildOrderByClause(QuerySpec spec)
+        private static void BuildOrderByClause(QuerySpec spec, StringBuilder sql)
         {
             if (spec.order != null && spec.order.Count > 0)
             {
@@ -131,7 +132,7 @@ private void BuildOrderByClause(QuerySpec spec)
             }
         }
 
-        private void BuildOffsetFetchClause(QuerySpec spec)
+        private static void BuildOffsetFetchClause(QuerySpec spec, StringBuilder sql)
         {
             if (spec.top == 0 && spec.skip == 0)
                 return; // Nothing to generate
@@ -150,10 +151,6 @@ private void BuildOffsetFetchClause(QuerySpec spec)
 
         }
 
-    }
-
-    public static class QueryBuilderExtension
-    {
         public static SqlCommand AsJson(this SqlCommand cmd)
         {
             cmd.CommandText += " for json path";