Added DbReverseForeignObject

Removed method SqlSerialise(DateTime ...)

Database-Attribute_System/Attributes/DbObject.cs

@@ -20,6 +20,7 @@ namespace eu.railduction.netcore.dll.Database_Attribute_System.Attributes
         public List<DbAttribute> attributeAttributes = new List<DbAttribute>() { };
         public List<DbForeignKey> foreignKeyAttributes = new List<DbForeignKey>() { };
         public List<DbForeignObject> foreignObjectAttributes = new List<DbForeignObject>() { };
+        public List<DbReverseForeignObject> reverseForeignObjectAttributes = new List<DbReverseForeignObject>() { };
 
         /// <summary>
         /// Marks variable as database-table
@@ -68,6 +69,11 @@ namespace eu.railduction.netcore.dll.Database_Attribute_System.Attributes
 
                         this.foreignObjectAttributes.Add(fobj);
                     }
+                    else if (fi.GetCustomAttribute(typeof(DbReverseForeignObject), true) is DbReverseForeignObject rfobj)    // ReverseForeignObjects
+                    {
+                        rfobj.Init(fi, this);
+                        this.reverseForeignObjectAttributes.Add(rfobj);
+                    }
                 }
                 catch(InvalidOperationException ex)
                 {

Database-Attribute_System/Attributes/DbReverseForeignObject.cs

@@ -0,0 +1,60 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Reflection;
+using System.Threading.Tasks;
+
+namespace eu.railduction.netcore.dll.Database_Attribute_System.Attributes
+{
+    [AttributeUsage(AttributeTargets.Field, Inherited = false, AllowMultiple = false)]
+    public class DbReverseForeignObject : Attribute
+    {
+        public Type foreignObjectType;
+
+        public string _foreignKeyName;
+        public DbForeignKey foreignKeyAttribute;
+
+        public FieldInfo parentField;
+        public DbObject classAttribute;
+
+        /// <summary>
+        /// Marks variable as reverse-foreign-object of an dbObject
+        /// </summary>
+        /// <param name="foreignKeyName">Fieldname of primaryKey associated with the reverseForeignObject (null if same as primary key) [Only works with 1 primaryKey]</param>
+        public DbReverseForeignObject(string foreignKeyName = null)
+        {
+            this._foreignKeyName = foreignKeyName;
+        }
+
+        public void Init(FieldInfo fi, DbObject classAttribute)
+        {
+            this.parentField = fi;
+            this.classAttribute = classAttribute;
+            this.foreignObjectType = fi.FieldType;
+
+            // Init foreign-object class
+            DbObject foreignClassAttribute = ClassAction.Init(this.foreignObjectType);
+
+            if (classAttribute.primaryKeyAttributes.Count < 1) throw new InvalidOperationException($"'{classAttribute.parentClassType.Name}' does not have a primaryKey.");
+            if (classAttribute.primaryKeyAttributes.Count > 1) throw new InvalidOperationException($"ReverseForeignObject does not support multiple primaryKeys.");
+            // Get primaryKey name if none is set
+            if (_foreignKeyName == null) _foreignKeyName = classAttribute.primaryKeyAttributes[0]._attributeName;
+
+            // Check if my primary-key is set in the foreign-class as foreignKey
+            DbPrimaryKey primaryKey = classAttribute.primaryKeyAttributes[0];
+            foreach (DbForeignKey foreignKey in foreignClassAttribute.foreignKeyAttributes)
+            {
+                if (primaryKey._attributeName.ToLower() == foreignKey._attributeName.ToLower())  // Name matches
+                    if (primaryKey.parentField.GetType() == foreignKey.parentField.GetType())   // Type matches
+                    {
+                        foreignKeyAttribute = foreignKey;
+                    }
+                    else
+                        // Same name, but wrong type
+                        throw new InvalidOperationException($"ForeignObject='{foreignClassAttribute.parentClassType.Name}' has invalid type foreignKey='{foreignKey.parentField.Name}' for object='{classAttribute.parentClassType.Name}' with primaryKey='{primaryKey.parentField.Name}'.");
+            }
+            // No match
+            if (foreignKeyAttribute == null) throw new InvalidOperationException($"ForeignObject='{foreignClassAttribute.parentClassType.Name}' is missing foreignKey for object='{classAttribute.parentClassType.Name}' with primaryKey='{primaryKey.parentField.Name}'.");
+        }
+    }
+}

Database-Attribute_System/ClassAction.cs

@@ -1,5 +1,6 @@
 using eu.railduction.netcore.dll.Database_Attribute_System.Attributes;
 using System;
+using System.Collections;
 using System.Collections.Generic;
 using System.Reflection;
 using System.Text;
@@ -126,7 +127,7 @@ namespace eu.railduction.netcore.dll.Database_Attribute_System
                 }
 
                 // If no data was found matching this field
-                if (!dataMatchFound) throw new InvalidOperationException($"Cannot create object with primaryKeyData. No data assigned to field '{primaryKeyAtt.parentField.Name}'");
+                if (!dataMatchFound) throw new InvalidOperationException($"PrimaryKey='{primaryKeyAtt.parentField.Name}' is missing.");
             }
 
             ResolveByPrimaryKey<T>(obj, queryExecutor);
@@ -276,22 +277,75 @@ namespace eu.railduction.netcore.dll.Database_Attribute_System
             // Read dbObject-attribute
             DbObject dbObject = ClassAction.Init(classType);
 
+            // Resolve foreignObjects
+
             foreach (DbForeignObject foreignObjectAtt in dbObject.foreignObjectAttributes)
             {
                 object foreignObject_value = foreignObjectAtt.parentField.GetValue(classObject);
 
-                // When its empty, get it
+                // When its empty, get it & set it
                 if(foreignObject_value == null)
                 {
                     foreignObject_value = GetByPrimaryKey<T>(classType, foreignObjectAtt.foreignKeyAttribute.parentField.GetValue(classObject), queryExecutor);
+                    foreignObjectAtt.parentField.SetValue(classObject, foreignObject_value);
                 }
 
                 // Recursive resolving
-                if (max_depth - 1 > 0)
+                if (max_depth > 1)
                 {
+                    // Go recursively into the next class
                     ResolveForeignKeys(foreignObject_value, queryExecutor, max_depth - 1);
                 }
             }
+
+            // Resolve reverseForeignObjects
+            foreach (DbReverseForeignObject reverseForeignObjectAtt in dbObject.reverseForeignObjectAttributes)
+            {
+                object reverseForeignObject_value = reverseForeignObjectAtt.parentField.GetValue(classObject);
+
+                // When its empty, get it & set it
+                if (reverseForeignObject_value == null)
+                {
+                    // Generate & set attribute-set
+                    Dictionary<string, object> attributes = new Dictionary<string, object>();
+                    attributes.Add(reverseForeignObjectAtt._foreignKeyName, dbObject.primaryKeyAttributes[0].parentField.GetValue(classObject));
+
+                    List<object> values = GetListByAttribute<object>(reverseForeignObjectAtt.foreignKeyAttribute.classAttribute.parentClassType, attributes, queryExecutor);
+
+                    if(values.Count == 0) throw new InvalidOperationException($"'{reverseForeignObjectAtt.parentField.Name}' could not been resolved. ReverseForeignObject returned '{values.Count}' values.");
+
+                    // Check for type to determen 1:1 or 1:m
+                    Type reverseForeignObject_type = reverseForeignObjectAtt.parentField.GetType();
+                    if (reverseForeignObject_type is IList && reverseForeignObject_type.IsGenericType)  // List, so 1:m
+                    {
+                        reverseForeignObject_value = values;
+                    }
+                    else    // Not list, so 1:1
+                    {
+                        if (values.Count > 1) throw new InvalidOperationException($"'{reverseForeignObjectAtt.parentField.Name}' could not been resolved as ReverseForeignObject returned '{values.Count}' values. (Is it 1:1 instead of 1:m?)");
+                        reverseForeignObject_value = values[0];
+                    }
+                    reverseForeignObjectAtt.parentField.SetValue(classObject, reverseForeignObject_value);
+                }
+
+                // Recursive resolving
+                if (max_depth > 1)
+                {
+                    if (reverseForeignObject_value is IList)  // 1:m
+                    {
+                        // If we have a list of objects, we need to recursively go into each one
+                        foreach(object value in (IList)reverseForeignObject_value)
+                        {
+                            ResolveForeignKeys(value, queryExecutor, max_depth - 1);
+                        }
+                    }
+                    else    // 1:1
+                    {
+                        // Go recursively into the next class
+                        ResolveForeignKeys(reverseForeignObject_value, queryExecutor, max_depth - 1);
+                    } 
+                }
+            }
         }
     }
 }

Database-Attribute_System/internal/Function.cs

@@ -14,11 +14,6 @@ namespace eu.railduction.netcore.dll.Database_Attribute_System
             return str_cpy;
         }
 
-        public static string SqlSerialise(DateTime dt, string format = "yyyy-MM-dd HH:mm:ss")
-        {
-            return dt.ToString(format);
-        }
-
         // Recursive object[] copying
         internal static void RecursiveParameterCopying(ref List<object> paramz, object[] objects)
         {
@@ -124,24 +119,24 @@ namespace eu.railduction.netcore.dll.Database_Attribute_System
 
         public static string SqlSerialise(object obj)
         {
-            if (obj == null)            // Handle null
+            if (obj == null || obj is DBNull)            // Handle null
             {
                 return "null";
             }
-            else if (obj.GetType() == typeof(string))       // Handle strings
+            else if (obj is string)       // Handle strings
             {
                 return "'" + SqlEscape((string)obj) + "'";  // wrap in sql-brackets and escape sql, if any
             }
-            else if (obj.GetType() == typeof(byte) || obj.GetType() == typeof(int) || obj.GetType() == typeof(float) || obj.GetType() == typeof(double))  // Handle int, float & double
+            else if (obj is byte || obj is int || obj is float || obj is double)  // Handle int, float & double
             {
                 return obj.ToString().Replace(",", ".");    // just format to string and form comma to sql-comma
             }
-            else if (obj.GetType() == typeof(DateTime))        // Handle DateTime
+            else if (obj is DateTime)        // Handle DateTime
             {
                 DateTime dateTime = (DateTime)obj;
-                return "'" + SqlSerialise(dateTime) + "'";     // wrap in sql-brackets and convert to sql-datetime
+                return "'" + dateTime.ToString("yyyy-MM-dd HH:mm:ss") + "'";     // wrap in sql-brackets and convert to sql-datetime
             }
-            else if (obj.GetType() == typeof(Guid))        // Handle Guid
+            else if (obj is Guid)        // Handle Guid
             {
                 string guid = ((Guid)obj).ToString();  // Get Guid as string
                 return "'" + guid + "'";                 // wrap in sql-brackets