feat: add reference and custom operations

src/DynaMight/AtomicOperations/CustomOperation.cs

@@ -0,0 +1,43 @@
+using Amazon.DynamoDBv2.DocumentModel;
+using Amazon.DynamoDBv2.Model;
+
+namespace DynaMight.AtomicOperations;
+
+/// <summary>
+/// Creates a custom operation, that receives Func to execute the internal methods.
+/// </summary>
+public class CustomOperation : IAtomicOperation
+{
+    private readonly string _getUpdateExpression;
+    private readonly (string, string) _getNameExpressionFunc;
+    private readonly (string, AttributeValue, DynamoDBEntry?) _getValueExpressionFunc;
+
+    /// <inheritdoc />
+    public string UpdateExpressionType {get; }
+
+    /// <inheritdoc />
+    public string GetUpdateExpression() => _getUpdateExpression;
+
+    /// <inheritdoc />
+    public (string key, string value) GetNameExpression() => _getNameExpressionFunc;
+
+    /// <inheritdoc />
+    public (string key, AttributeValue AttributeValue, DynamoDBEntry? dynamoDbEntry) GetValueExpression() =>
+        _getValueExpressionFunc;
+
+    /// <summary>
+    /// Creates a custom operation, that receives Func to execute the internal methods.
+    /// </summary>
+    /// <param name="updateExpressionType">Value for <see cref="UpdateExpressionType"/>.</param>
+    /// <param name="getUpdateExpression">Value for <see cref="GetUpdateExpression"/>.</param>
+    /// <param name="getNameExpressionFunc">Value for <see cref="GetNameExpression"/>.</param>
+    /// <param name="getValueExpressionFunc">Value for <see cref="GetValueExpression"/>.</param>
+    public CustomOperation(string updateExpressionType, string getUpdateExpression,
+        (string, string) getNameExpressionFunc, (string, AttributeValue, DynamoDBEntry?) getValueExpressionFunc)
+    {
+        UpdateExpressionType = updateExpressionType;
+        _getUpdateExpression = getUpdateExpression;
+        _getNameExpressionFunc = getNameExpressionFunc;
+        _getValueExpressionFunc = getValueExpressionFunc;
+    }
+}

src/DynaMight/AtomicOperations/ReferenceOperation.cs

@@ -0,0 +1,32 @@
+using Amazon.DynamoDBv2.DocumentModel;
+using Amazon.DynamoDBv2.Model;
+
+namespace DynaMight.AtomicOperations;
+
+/// <summary>
+/// Creates an reference entry for the atomic operation
+/// </summary>
+public class ReferenceOperation : IAtomicOperation
+{
+    /// <inheritdoc />
+    public string UpdateExpressionType => string.Empty;
+    private string FieldName { get; }
+
+    /// <inheritdoc />
+    public string GetUpdateExpression() => string.Empty;
+
+    /// <inheritdoc />
+    public (string key, string value) GetNameExpression() => ($"#{FieldName}", FieldName);
+
+    /// <inheritdoc />
+    public (string key, AttributeValue AttributeValue, DynamoDBEntry? dynamoDbEntry) GetValueExpression() => (string.Empty, null!, null);
+
+    /// <summary>
+    /// Creates an reference entry in the AtomicBuilder. Should be used with the CustomOperation
+    /// </summary>
+    /// <param name="fieldName">The field's name that will be added. Recommended to use `nameof` function to avoid issues when renaming.</param>
+    public ReferenceOperation(string fieldName)
+    {
+        FieldName = fieldName;
+    }
+}

src/DynaMight/Builders/AtomicBuilder.cs

@@ -40,6 +40,9 @@ public IAtomicBuilder AddOperation(IAtomicOperation atomicOperation)
 
         AddNameExpression(nameExpression);
 
+        if (string.IsNullOrEmpty(atomicOperation.UpdateExpressionType))
+            return this;
+
         if (!_atomicOperations.ContainsKey(atomicOperation.UpdateExpressionType))
             _atomicOperations.Add(atomicOperation.UpdateExpressionType, new List<IAtomicOperation>());
 

tests/DynaMight.UnitTests/Builders/AtomicBuilderTests.cs

@@ -2,6 +2,7 @@
 using Amazon.DynamoDBv2.Model;
 using DynaMight.AtomicOperations;
 using DynaMight.Builders;
+using DynaMight.Converters;
 using DynaMight.Criteria;
 using FluentAssertions;
 
@@ -137,7 +138,7 @@ public void SetTableName_WhenConfigNotEmpty()
         var config = builder.Build();
         config.TableName.Should().Be("22cans_DynaMightTestClass");
     }
-    
+
     [Fact]
     public void SetTableName_WhenConfigEmpty()
     {
@@ -149,7 +150,7 @@ public void SetTableName_WhenConfigEmpty()
         var config = builder.Build();
         config.TableName.Should().Be("DynaMightTestClass");
     }
-    
+
     [Fact]
     public void Operation_WhenConditionTrue()
     {
@@ -171,7 +172,8 @@ public void Operation_WhenConditionTrue()
         });
     }
 
-    [Fact] public void Operation_WhenConditionFalse()
+    [Fact]
+    public void Operation_WhenConditionFalse()
     {
         var builder = AtomicBuilder
             .Create()
@@ -205,7 +207,7 @@ public void OneOperation()
             { $":{Field2Name}", new AttributeValue { N = Field2Value.ToString() } }
         });
     }
-    
+
     [Fact]
     public void TwoOperationsSameKind()
     {
@@ -229,7 +231,7 @@ public void TwoOperationsSameKind()
             { $":{Field3Name}", new AttributeValue { N = Field3Value.ToString() } }
         });
     }
-    
+
     [Fact]
     public void TwoOperationsDifferentKind()
     {
@@ -253,7 +255,7 @@ public void TwoOperationsDifferentKind()
             { $":{Field3Name}", new AttributeValue { N = Field3Value.ToString() } }
         });
     }
-    
+
     [Fact]
     public void AddTwoOperationsForSameField_KeepsTheFirst()
     {
@@ -274,7 +276,7 @@ public void AddTwoOperationsForSameField_KeepsTheFirst()
             { $":{Field2Name}", new AttributeValue { N = Field2Value.ToString() } }
         });
     }
-    
+
     [Fact]
     public void AddTwoOperationsForSameField_KeepsTheFirst_AndCriteriaBefore()
     {
@@ -296,7 +298,7 @@ public void AddTwoOperationsForSameField_KeepsTheFirst_AndCriteriaBefore()
             { $":{Field2Name}", new AttributeValue { N = Field2Value.ToString() } }
         });
     }
-    
+
     [Fact]
     public void AddOperationWithEmptyKeyField_DontAdd()
     {
@@ -317,4 +319,49 @@ public void AddOperationWithEmptyKeyField_DontAdd()
             { $":{Field2Name}", new AttributeValue { N = Field2Value.ToString() } }
         });
     }
+
+    [Fact]
+    public void AddReferenceOperation()
+    {
+        var builder = AtomicBuilder
+            .Create()
+            .AddOperation(new ReferenceOperation(Field1Name));
+
+        var config = builder.Build();
+        config.UpdateExpression.Should().BeEmpty();
+
+        config.ExpressionAttributeNames.Should().BeEquivalentTo(new Dictionary<string, string>
+        {
+            { $"#{Field1Name}", Field1Name }
+        });
+        config.ExpressionAttributeValues.Should().BeEmpty();
+    }
+
+    [Fact]
+    public void AddCustomOperationWithReference()
+    {
+        var builder = AtomicBuilder
+            .Create()
+            .AddOperation(new CustomOperation(
+                "SET",
+                $"#{Field1Name} = :{Field1Name} + #{Field2Name}",
+                ($"#{Field1Name}", Field1Name),
+                ($":{Field1Name}", DynamoValueConverter.ToAttributeValue(Field1Value),
+                    DynamoValueConverter.ToDynamoDbEntry(Field1Value))
+            ))
+            .AddOperation(new ReferenceOperation(Field2Name));
+
+        var config = builder.Build();
+        config.UpdateExpression.Should().Be($"SET #{Field1Name} = :{Field1Name} + #{Field2Name}");
+
+        config.ExpressionAttributeNames.Should().BeEquivalentTo(new Dictionary<string, string>
+        {
+            { $"#{Field1Name}", Field1Name },
+            { $"#{Field2Name}", Field2Name }
+        });
+        config.ExpressionAttributeValues.Should().BeEquivalentTo(new Dictionary<string, AttributeValue>
+        {
+            { $":{Field1Name}", new AttributeValue { S = Field1Value } }
+        });
+    }
 }