json functions support

src/YesSql.Core/Sql/JsonPathExpressionFunction.cs

@@ -0,0 +1,35 @@
+using System;
+
+namespace YesSql.Sql
+{
+    public class JsonPathExpressionFunction : ISqlFunction
+    {
+        private readonly string _template;
+        private readonly int[] _argumentIds;
+
+        public JsonPathExpressionFunction(string template, params int[] argumentIds)
+        {
+            _template = template;
+            _argumentIds = argumentIds;
+        }
+
+        public string Render(string[] arguments)
+        {
+            foreach (var id in _argumentIds)
+            {
+                arguments[id] = TransformPathExpression(arguments[id]);
+            }
+            return String.Format(_template, arguments);
+        }
+
+        private string TransformPathExpression(string jsonPathExpression)
+        {
+            return jsonPathExpression
+                .Replace("$.", "")
+                .Replace("[", ",")
+                .Replace("].", ",")
+                .Replace("]", "")
+                .Replace(".", ",");
+        }
+    }
+}

src/YesSql.Provider.MySql/MySqlDialect.cs

@@ -87,6 +87,8 @@ public MySqlDialect()
         {
             AddTypeHandler<TimeSpan, long>(x => x.Ticks);
             Methods.Add("now", new TemplateFunction("UTC_TIMESTAMP()"));
+
+            Methods.Add("JSON_MODIFY", new TemplateFunction("json_set({0}, {1}, {2})"));
         }
 
         public override string Name => "MySql";

src/YesSql.Provider.PostgreSql/PostgreSqlDialect.cs

@@ -95,6 +95,9 @@ public PostgreSqlDialect()
             Methods.Add("month", new TemplateFunction("extract(month from {0})"));
             Methods.Add("year", new TemplateFunction("extract(year from {0})"));
             Methods.Add("now", new TemplateFunction("now() at time zone 'utc'"));
+
+            Methods.Add("JSON_VALUE", new JsonPathExpressionFunction("{0}::json#>>string_to_array({1}, ',')", 1));
+            Methods.Add("JSON_MODIFY", new JsonPathExpressionFunction("jsonb_set({0}, string_to_array({1}, ','), to_jsonb({2}), false)", 1));
         }
 
         public override string Name => "PostgreSql";

src/YesSql.Provider.Sqlite/SqliteDialect.cs

@@ -91,6 +91,9 @@ public SqliteDialect()
             Methods.Add("month", new TemplateFunction("cast(strftime('%m', {0}) as int)"));
             Methods.Add("year", new TemplateFunction("cast(strftime('%Y', {0}) as int)"));
             Methods.Add("now", new TemplateFunction("DATETIME('now')"));
+
+            Methods.Add("JSON_VALUE", new TemplateFunction("json_extract({0}, {1})"));
+            Methods.Add("JSON_MODIFY", new TemplateFunction("json_set({0}, {1}, {2})"));
         }
 
         public override string Name => "Sqlite";

test/YesSql.Tests/CoreTests.cs

@@ -4372,6 +4372,45 @@ public async Task SqlNowFunction()
             Assert.Equal(10, publishedInThePastResult);
         }
 
+        [Theory]
+        [InlineData("JSON_VALUE", "'{ \"a\" : 1, \"b\" : 2 }'", "'$.b'", "2")]
+        [InlineData("JSON_VALUE", "'{ \"a\" : { \"b\" : { \"c\" : 3 } } }'", "'$.a.b.c'", "3")]
+        [InlineData("JSON_VALUE", "'{ \"a\" : { \"b\" : [{ \"c\" : 1 }, { \"c\" : 2 }, { \"c\" : 3 }] } }'", "'$.a.b[2].c'", "3")]
+        public async Task SqlJsonValueFunction(string method, string json, string jsonPathExpression, string expected)
+        {
+            string result;
+
+            using (var connection = _store.Configuration.ConnectionFactory.CreateConnection())
+            {
+                await connection.OpenAsync();
+                var dialect = _store.Configuration.SqlDialect;
+                var sql = "SELECT " + dialect.RenderMethod(method, json, jsonPathExpression);
+                result = await connection.QueryFirstOrDefaultAsync<string>(sql);
+            }
+
+            Assert.Equal(expected, result);
+        }
+
+        [Theory]
+        [InlineData("JSON_MODIFY", "'{\"a\":1,\"b\":2}'", "'$.b'", "3", "{\"a\":1,\"b\":3}")]
+        [InlineData("JSON_MODIFY", "'{ \"a\" : { \"b\" : { \"c\" : 3 } } }'", "'$.a.b.c'", "4", "{\"a\":{\"b\":{\"c\":4}}}")]
+        [InlineData("JSON_MODIFY", "'{ \"a\" : { \"b\" : [{ \"c\" : 1 }, { \"c\" : 2 }, { \"c\" : 3 }] } }'", "'$.a.b[2].c'", "5", "{\"a\":{\"b\":[{\"c\":1},{\"c\":2},{\"c\":5}]}}")]
+        public async Task SqlJsonModifyFunction(string method, string json, string jsonPathExpression, string newValue, string expected)
+        {
+            string result;
+
+            using (var connection = _store.Configuration.ConnectionFactory.CreateConnection())
+            {
+                await connection.OpenAsync();
+
+                var dialect = _store.Configuration.SqlDialect;
+                var sql = "SELECT " + dialect.RenderMethod(method, json, jsonPathExpression, newValue);
+                result = await connection.QueryFirstOrDefaultAsync<string>(sql);
+            }
+            //we are getting rid of unnecessary JSON formatting
+            Assert.Equal(expected, result.Replace(": ", ":").Replace(" :", ":").Replace(", ", ",").Replace("{ ", "{").Replace(" }", "}"));
+        }
+
         [Fact]
         public virtual async Task CanUseStaticMethodsInLinqQueries()
         {