Added DbIntermediateForeignObject and resolver

Set version to 1.5.20

Database-Attribute_System/Attributes/DbIntermediateForeignObject.cs

@@ -0,0 +1,80 @@
+using System;
+using System.Collections;
+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 DbIntermediateForeignObject : Attribute
+    {
+        public Type foreignObjectType;
+
+        public string _intermediateTableName;
+
+        public string _keyName;
+        public string _foreignKeyName;
+
+
+        public DbPrimaryKey foreignPrimaryKeyAttribute;
+
+        public FieldInfo parentField;
+        public DbObject classAttribute;
+
+        /// <summary>
+        /// Marks variable as intermediate-object of an dbObject
+        /// </summary>
+        /// <param name="intermediateTableName">Table-name of intermediate-table. Must contain primaryKey of this class & target class</param>
+        /// <param name="keyName">Fieldname of primaryKey associated with the IntermediateObject on this side [m]:n (null if same as primary key) [Only works with 1 primaryKey]</param>
+        /// <param name="foreignKeyName">Fieldname of primaryKey associated with the IntermediateObject on the other side m:[n] (null if same as primary key) [Only works with 1 primaryKey]</param>
+        public DbIntermediateForeignObject(string intermediateTableName, string keyName = null, string foreignKeyName = null)
+        {
+            this._intermediateTableName = intermediateTableName;
+            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($"'{classAttribute.parentClassType.Name}' does not have a primaryKey.");
+            if (classAttribute.primaryKeyAttributes.Count > 1) throw new InvalidOperationException($"IntermediateObject does not support multiple primaryKeys.");
+            // Get primaryKey name if none is set
+            if (_keyName == null) _keyName = classAttribute.primaryKeyAttributes[0]._attributeName;
+
+            if (!(fi.FieldType is IList && fi.FieldType.IsGenericType))  // 1:m
+                throw new InvalidOperationException($"IntermediateObject has to be typeof(List<T>). Maybe you meant to use DbForeignObject or DbReverseForeignObject for 1:m or 1:1 relations.");
+
+            // Check the generic list and get inner-type
+            Type foreignObjectType = null;
+            foreach (Type interfaceType in fi.FieldType.GetInterfaces())
+            {
+                if (interfaceType.IsGenericType &&
+                    interfaceType.GetGenericTypeDefinition()
+                    == typeof(IList<>))
+                {
+                    foreignObjectType = fi.FieldType.GetGenericArguments()[0];
+                    break;
+                }
+            }
+            if (foreignObjectType == null) throw new InvalidOperationException("Could not read innter-type of generic-list!");
+
+            // Now get the primaryKey from my foreignObject
+            DbObject foreignDbObject = ClassAction.Init(foreignObjectType);
+            // Check the primaryKey/s
+            if (foreignDbObject.primaryKeyAttributes.Count < 1) throw new InvalidOperationException($"'{foreignDbObject.parentClassType.Name}' does not have a primaryKey.");
+            if (foreignDbObject.primaryKeyAttributes.Count > 1) throw new InvalidOperationException($"IntermediateObject does not support multiple primaryKeys. (Found '{foreignDbObject.primaryKeyAttributes.Count}' in '{foreignDbObject.parentClassType.Name}')");
+            // Save it
+            foreignPrimaryKeyAttribute = foreignDbObject.primaryKeyAttributes[0];
+
+            if (_foreignKeyName == null) _foreignKeyName = foreignPrimaryKeyAttribute._attributeName;
+        }
+    }
+}

Database-Attribute_System/Attributes/DbObject.cs

@@ -21,6 +21,7 @@ namespace eu.railduction.netcore.dll.Database_Attribute_System.Attributes
         public List<DbForeignKey> foreignKeyAttributes = new List<DbForeignKey>() { };
         public List<DbForeignObject> foreignObjectAttributes = new List<DbForeignObject>() { };
         public List<DbReverseForeignObject> reverseForeignObjectAttributes = new List<DbReverseForeignObject>() { };
+        public List<DbIntermediateForeignObject> intermediateObjectAttributes = new List<DbIntermediateForeignObject>() { };
 
         /// <summary>
         /// Marks variable as database-table
@@ -74,6 +75,11 @@ namespace eu.railduction.netcore.dll.Database_Attribute_System.Attributes
                         rfobj.Init(fi, this);
                         this.reverseForeignObjectAttributes.Add(rfobj);
                     }
+                    else if (fi.GetCustomAttribute(typeof(DbIntermediateForeignObject), true) is DbIntermediateForeignObject iobj)    // ReverseForeignObjects
+                    {
+                        iobj.Init(fi, this);
+                        this.intermediateObjectAttributes.Add(iobj);
+                    }
                 }
                 catch(InvalidOperationException ex)
                 {

Database-Attribute_System/ClassAction.cs

@@ -278,7 +278,6 @@ namespace eu.railduction.netcore.dll.Database_Attribute_System
             DbObject dbObject = ClassAction.Init(classType);
 
             // Resolve foreignObjects
-
             foreach (DbForeignObject foreignObjectAtt in dbObject.foreignObjectAttributes)
             {
                 object foreignObject_value = foreignObjectAtt.parentField.GetValue(classObject);
@@ -322,6 +321,62 @@ namespace eu.railduction.netcore.dll.Database_Attribute_System
                 }
             }
 
+            // Resolve intermediateForeignObjects
+            foreach (DbIntermediateForeignObject intermediateForeignObjectAtt in dbObject.intermediateObjectAttributes)
+            {
+                object intermediateForeignObject_value = intermediateForeignObjectAtt.parentField.GetValue(classObject);
+
+                // When its empty, get it & set it
+                if (intermediateForeignObject_value == null)
+                {
+                    // Generate & set attribute-set
+                    Dictionary<string, object> attributes = new Dictionary<string, object>();
+                    attributes.Add(intermediateForeignObjectAtt._keyName, dbObject.primaryKeyAttributes[0].parentField.GetValue(classObject));
+
+                    string query = QueryBuilder.SelectByAttribute(intermediateForeignObjectAtt._intermediateTableName, attributes);   // Generate query
+                    List<Dictionary<string, object>> dataSet = queryExecutor(query);    // Execute
+                    // Extract data
+                    List<object> values = new List<object>();
+                    for (int i=0; i<dataSet.Count; i++)
+                    {
+                        Dictionary<string, object> data = dataSet[i];
+                        object primaryKeyValue = data[intermediateForeignObjectAtt.foreignPrimaryKeyAttribute._attributeName];
+
+                        values.Add(GetByPrimaryKey<object>(intermediateForeignObjectAtt.foreignPrimaryKeyAttribute.classAttribute.parentClassType, primaryKeyValue, queryExecutor));
+                    }
+
+                    // Now scan the just resolved class to be able to set myself
+                    DbObject foreignDbObject = Init(intermediateForeignObjectAtt.foreignPrimaryKeyAttribute.classAttribute.parentClassType);
+                    foreach (DbForeignObject dbForeignObject in foreignDbObject.foreignObjectAttributes)
+                    {
+                        // If the field-names match
+                        if (dbForeignObject._foreignKeyName.ToLower() == dbObject.primaryKeyAttributes[0]._attributeName.ToLower())
+                        {
+                            object myReference = classObject;
+                            foreach (object value in values)
+                            {
+                                dbForeignObject.parentField.SetValue(value, myReference);
+                            }
+                            break;
+                        }
+                    }
+
+                    // Set value
+                    intermediateForeignObject_value = values;
+                    intermediateForeignObjectAtt.parentField.SetValue(classObject, intermediateForeignObject_value);
+                }
+
+                // Recursive resolving
+                if (max_depth > 1)
+                {
+                    // If we have a list of objects, we need to recursively go into each one
+                    foreach (object value in (IList)intermediateForeignObject_value)
+                    {
+                        ResolveForeignKeys(value, queryExecutor, max_depth - 1);
+                    }
+                }
+            }
+
             // Resolve reverseForeignObjects
             foreach (DbReverseForeignObject reverseForeignObjectAtt in dbObject.reverseForeignObjectAttributes)
             {

Database-Attribute_System/Database-Attribute_System.csproj

@@ -4,7 +4,7 @@
     <TargetFramework>netcoreapp2.1</TargetFramework>
     <RootNamespace>eu.railduction.netcore.dll.Database_Attribute_System</RootNamespace>
     <SignAssembly>false</SignAssembly>
-    <Version>1.5.15</Version>
+    <Version>1.5.20</Version>
   </PropertyGroup>
 
 </Project>