Database Helper Class Library to Ease Database Operation

///////////////////////////////////////////////////////////////////////////
// Copyright 2003-2005 Falcon Soon
//
// Author: Soon Chun Boon
// Date: 20 September 2004
// Description: 
// Class that represents data relationship between 2 tables.
///////////////////////////////////////////////////////////////////////////

using System;
using System.ComponentModel;
using System.Data;

namespace DBHelper
{
	/// <summary>
	/// Class that represents data relationship between 2 tables.
	/// </summary>
	public class DBRelation
	{
        #region Class Member Declarations
        private DBKey mobjParentKey;
        private DBKey mobjChildKey;
        private bool mbCreateConstraints;
        private string mstrRelationName;
        private ICommonDBAccess mitcParent;
        private ICommonDBAccess mitcChild;
        private string[] mastrParentColumnName;
        private string[] mastrChildColumnName;
        private string mstrParentTableName;
        private string mstrChildTableName;
        private string mstrParentColumnNames;
        private string mstrChildColumnNames;
        //private bool mbNested;
        #endregion

        #region Class Constructors
        /// <summary>
        /// Initialize a new instance of <see cref="DBHelper.DBRelation"/> by providing single parent
        /// and child key.
        /// </summary>
        /// <param name="strRelationName">Relationship name.</param>
        /// <param name="itcParent">Instance of parent storage.</param>
        /// <param name="itcChild">Instance of child storage.</param>
        /// <param name="colParent">Single column represents parent key.</param>
        /// <param name="colChild">Sindle column represents child key.</param>
        /// <exception cref="DBHelper.DataException.ColumnNotInAnyTable">
        /// A <see cref="System.Data.DataColumn"/> in <see cref="DBHelper.DBKey"/> 
        /// is not belonging to any <see cref="System.Data.DataTable"/>.
        /// </exception>
        /// <exception cref="DBHelper.DataException.KeyTableMismatch">
        /// <see cref="System.Data.DataTable"/> for every <see cref="System.Data.DataColumn"/>
        /// in <see cref="DBHelper.DBKey"/> is not same.
        /// </exception>
        /// <exception cref="DBHelper.DataException.KeyColumnsIdentical">
        /// Parent keys and child keys refers to same data columns.
        /// </exception>
        /// <exception cref="DBHelper.DataException.ColumnsTypeMismatch">
        /// Columns type for parent keys and child keys are mismatched.
        /// </exception>
        public DBRelation(string strRelationName, ICommonDBAccess itcParent, ICommonDBAccess itcChild,
            DataColumn colParent, DataColumn colChild) : 
            this(strRelationName, itcParent, itcChild, colParent, colChild, true)
        {
        }

        /// <summary>
        /// Initialize a new instance of <see cref="DBHelper.DBRelation"/> by providing multiple
        /// parent and child keys.
        /// </summary>
        /// <param name="strRelationName">Relationship name.</param>
        /// <param name="itcParent">Instance of parent storage.</param>
        /// <param name="itcChild">Instance of child storage.</param>
        /// <param name="acolParent">An array of columns represent parent keys.</param>
        /// <param name="acolChild">An array of columns represent child keys.</param>
        /// <exception cref="DBHelper.DataException.KeyLengthMismatch">
        /// Parent columns length is not same as child columns length.
        /// </exception>
        /// <exception cref="DBHelper.DataException.ColumnNotInAnyTable">
        /// A <see cref="System.Data.DataColumn"/> in <see cref="DBHelper.DBKey"/> 
        /// is not belonging to any <see cref="System.Data.DataTable"/>.
        /// </exception>
        /// <exception cref="DBHelper.DataException.KeyTableMismatch">
        /// <see cref="System.Data.DataTable"/> for every <see cref="System.Data.DataColumn"/>
        /// in <see cref="DBHelper.DBKey"/> is not same.
        /// </exception>
        /// <exception cref="DBHelper.DataException.KeyColumnsIdentical">
        /// Parent keys and child keys refers to same data columns.
        /// </exception>
        /// <exception cref="DBHelper.DataException.ColumnsTypeMismatch">
        /// Columns type for parent keys and child keys are mismatched.
        /// </exception>
        public DBRelation(string strRelationName, ICommonDBAccess itcParent, ICommonDBAccess itcChild,
            DataColumn[] acolParent, DataColumn[] acolChild) : 
            this(strRelationName, itcParent, itcChild, acolParent, acolChild, true)
        {
        }

        /// <summary>
        /// Initialize a new instance of <see cref="DBHelper.DBRelation"/> by providing single
        /// parent and child key and with specified constraint creation boolean.
        /// </summary>
        /// <param name="strRelationName">Relationship name.</param>
        /// <param name="itcParent">Instance of parent storage.</param>
        /// <param name="itcChild">Instance of child storage.</param>
        /// <param name="colParent">Single column represents parent key.</param>
        /// <param name="colChild">Single column represents child key.</param>
        /// <param name="bCreateConstraints">True if constraints is created, otherwise False.</param>
        /// <remarks>
        /// Constraints creation is not implemented yet.
        /// </remarks>
        /// <exception cref="DBHelper.DataException.ColumnNotInAnyTable">
        /// A <see cref="System.Data.DataColumn"/> in <see cref="DBHelper.DBKey"/> 
        /// is not belonging to any <see cref="System.Data.DataTable"/>.
        /// </exception>
        /// <exception cref="DBHelper.DataException.KeyTableMismatch">
        /// <see cref="System.Data.DataTable"/> for every <see cref="System.Data.DataColumn"/>
        /// in <see cref="DBHelper.DBKey"/> is not same.
        /// </exception>
        /// <exception cref="DBHelper.DataException.KeyColumnsIdentical">
        /// Parent keys and child keys refers to same data columns.
        /// </exception>
        /// <exception cref="DBHelper.DataException.ColumnsTypeMismatch">
        /// Columns type for parent keys and child keys are mismatched.
        /// </exception>
        public DBRelation(string strRelationName, ICommonDBAccess itcParent, ICommonDBAccess itcChild,
            DataColumn colParent, DataColumn colChild, bool bCreateConstraints)
        {
            //this.extendedProperties = null;
            this.mstrRelationName = "";
            //this.onPropertyChangingDelegate = null;
            this.mitcParent = null;
            this.mitcChild = null;
            this.mobjParentKey = null;
            this.mobjChildKey = null;
            //this.parentKeyConstraint = null;
            //this.childKeyConstraint = null;
            this.mstrParentColumnNames = null;
            this.mstrChildColumnNames = null;
            this.mstrParentTableName = null;
            this.mstrChildTableName = null;
            //this.mbNested = false;
            DataColumn[] acolParent = new DataColumn[1];
            acolParent[0] = colParent;
            DataColumn[] acolChild = new DataColumn[1];
            acolChild[0] = colChild;
            this.Create(strRelationName, itcParent, itcChild, acolParent, acolChild, bCreateConstraints);
        }

        /// <summary>
        /// Initialize a new instance of <see cref="DBHelper.DBRelation"/> by providing multiple
        /// parent and child keys and with specified constraint creation boolean.
        /// </summary>
        /// <param name="strRelationName">Relationship name.</param>
        /// <param name="itcParent">Instance of parent storage.</param>
        /// <param name="itcChild">Instance of child storage.</param>
        /// <param name="acolParent">An array of columns represents parent keys.</param>
        /// <param name="acolChild">An array of columns represents child keys.</param>
        /// <param name="bCreateConstraints">True if constraints is created, otherwise False.</param>
        /// <remarks>
        /// Constraints creation is not implemented yet.
        /// </remarks>
        /// <exception cref="DBHelper.DataException.KeyLengthMismatch">
        /// Parent columns length is not same as child columns length.
        /// </exception>
        /// <exception cref="DBHelper.DataException.ColumnNotInAnyTable">
        /// A <see cref="System.Data.DataColumn"/> in <see cref="DBHelper.DBKey"/> 
        /// is not belonging to any <see cref="System.Data.DataTable"/>.
        /// </exception>
        /// <exception cref="DBHelper.DataException.KeyTableMismatch">
        /// <see cref="System.Data.DataTable"/> for every <see cref="System.Data.DataColumn"/>
        /// in <see cref="DBHelper.DBKey"/> is not same.
        /// </exception>
        /// <exception cref="DBHelper.DataException.KeyColumnsIdentical">
        /// Parent keys and child keys refers to same data columns.
        /// </exception>
        /// <exception cref="DBHelper.DataException.ColumnsTypeMismatch">
        /// Columns type for parent keys and child keys are mismatched.
        /// </exception>
        public DBRelation(string strRelationName, ICommonDBAccess itcParent, ICommonDBAccess itcChild,
            DataColumn[] acolParent, DataColumn[] acolChild, bool bCreateConstraints)
        {
            //this.extendedProperties = null;
            this.mstrRelationName = "";
            //this.onPropertyChangingDelegate = null;
            this.mitcParent = null;
            this.mitcChild = null;
            this.mobjParentKey = null;
            this.mobjChildKey = null;
            //this.parentKeyConstraint = null;
            //this.childKeyConstraint = null;
            this.mstrParentColumnNames = null;
            this.mstrChildColumnNames = null;
            this.mstrParentTableName = null;
            this.mstrChildTableName = null;
            //this.mbNested = false;
            this.Create(strRelationName, itcParent, itcChild, acolParent, acolChild, bCreateConstraints);
        }

//        [Browsable(false)]
//        public DBRelation(string strRelationName, string strParentTableName, string strChildTableName, 
//            string[] astrParentColumnName, string[] astrChildColumnName, bool bNested)
//        {
//            //this.extendedProperties = null;
//            this.mstrRelationName = "";
//            //this.onPropertyChangingDelegate = null;
//            this.mobjParentKey = null;
//            this.mobjChildKey = null;
//            //this.parentKeyConstraint = null;
//            //this.childKeyConstraint = null;
//            this.mastrParentColumnName = null;
//            this.mastrChildColumnName = null;
//            this.mstrParentTableName = null;
//            this.mstrChildTableName = null;
//            this.mbNested = false;
//            this.mstrRelationName = strRelationName;
//            this.mastrParentColumnName = astrParentColumnName;
//            this.mastrChildColumnName = astrChildColumnName;
//            this.mstrParentTableName = strParentTableName;
//            this.mstrChildTableName = strChildTableName;
//            this.mbNested = bNested;
//        }
        #endregion

        /// <summary>
        /// Create a new instance of <see cref="DBHelper.DBRelation"/>.
        /// </summary>
        /// <param name="strRelationName">Relationship name.</param>
        /// <param name="itcParent">Instance of parent storage.</param>
        /// <param name="itcChild">Instance of child storage.</param>
        /// <param name="acolParent">An array of columns represents parent keys.</param>
        /// <param name="acolChild">An array of columns represents child keys.</param>
        /// <param name="bCreateConstraints">True if constraints is created, otherwise False.</param>
        /// <remarks>
        /// Constraints creation is not implemented yet.<br/>
        /// <p>
        /// If provided relationship name is null, relationship name will be empty string by default.
        /// </p>
        /// </remarks>
        /// <exception cref="DBHelper.DataException.KeyLengthMismatch">
        /// Parent columns length is not same as child columns length.
        /// </exception>
        /// <exception cref="DBHelper.DataException.ColumnNotInAnyTable">
        /// A <see cref="System.Data.DataColumn"/> in <see cref="DBHelper.DBKey"/> 
        /// is not belonging to any <see cref="System.Data.DataTable"/>.
        /// </exception>
        /// <exception cref="DBHelper.DataException.KeyTableMismatch">
        /// <see cref="System.Data.DataTable"/> for every <see cref="System.Data.DataColumn"/>
        /// in <see cref="DBHelper.DBKey"/> is not same.
        /// </exception>
        /// <exception cref="DBHelper.DataException.KeyColumnsIdentical">
        /// Parent keys and child keys refers to same data columns.
        /// </exception>
        /// <exception cref="DBHelper.DataException.ColumnsTypeMismatch">
        /// Columns type for parent keys and child keys are mismatched.
        /// </exception>
        private void Create(string strRelationName, ICommonDBAccess itcParent, ICommonDBAccess itcChild,
            DataColumn[] acolParent, DataColumn[] acolChild, bool bCreateConstraints)
        {
            this.mitcParent = itcParent;
            this.mitcChild = itcChild;
            this.mobjParentKey = new DBKey(acolParent);
            this.mobjChildKey = new DBKey(acolChild);
            if (acolParent.Length != acolChild.Length)
            {
                throw new DataException.KeyLengthMismatch();
            }
            this.CheckState();
            this.mstrRelationName = ((strRelationName == null) ? "" : strRelationName);
            this.mbCreateConstraints = bCreateConstraints;
        }

        /// <summary>
        /// Validates the provided parent keys and child keys.
        /// </summary>
        /// <exception cref="DBHelper.DataException.ColumnNotInAnyTable">
        /// A <see cref="System.Data.DataColumn"/> in <see cref="DBHelper.DBKey"/> 
        /// is not belonging to any <see cref="System.Data.DataTable"/>.
        /// </exception>
        /// <exception cref="DBHelper.DataException.KeyTableMismatch">
        /// <see cref="System.Data.DataTable"/> for every <see cref="System.Data.DataColumn"/>
        /// in <see cref="DBHelper.DBKey"/> is not same.
        /// </exception>
        /// <exception cref="DBHelper.DataException.KeyColumnsIdentical">
        /// Parent keys and child keys refers to same data columns.
        /// </exception>
        /// <exception cref="DBHelper.DataException.ColumnsTypeMismatch">
        /// Columns type for parent keys and child keys are mismatched.
        /// </exception>
        internal void CheckState()
        {
            this.mobjParentKey.CheckState();
            this.mobjChildKey.CheckState();
            
            if (this.mobjChildKey.ColumnsEqual(this.mobjParentKey))
            {
                throw new DataException.KeyColumnsIdentical();
            }
            for (int iIndex = 0; (iIndex < this.mobjParentKey.Columns.Length); iIndex++)
            {
                if (this.mobjParentKey.Columns[iIndex].DataType != this.mobjChildKey.Columns[iIndex].DataType)
                {
                    throw new DataException.ColumnsTypeMismatch();
                }
            }
        }

        /// <summary>
        /// Validation performed when instance property is accessed.
        /// </summary>
        /// <exception cref="DBHelper.DataException.BadObjectPropertyAccess">
        /// Instance becomes bad while property being accessed.
        /// </exception>
        protected void CheckStateForProperty()
        {
            try
            {
                this.CheckState();
                return;
            }
            catch (Exception ex)
            {
                throw new DataException.BadObjectPropertyAccess(ex.Message);
            }
        }

        #region Class Property Declarations
        /// <summary>
        /// Returns <see cref="System.Data.DataColumn"/> of parent keys.
        /// </summary>
        /// <exception cref="DBHelper.DataException.BadObjectPropertyAccess">
        /// Instance becomes bad while property being accessed.
        /// </exception>
        public virtual DataColumn[] ParentColumns
        {
            get
            {
                this.CheckStateForProperty();
                return this.mobjParentKey.Columns;
            }
        }

        /// <summary>
        /// Returns parent <see cref="DBHelper.DBKey"/>.
        /// </summary>
        /// <exception cref="DBHelper.DataException.BadObjectPropertyAccess">
        /// Instance becomes bad while property being accessed.
        /// </exception>
        internal virtual DBKey ParentKey
        {
            get
            {
                this.CheckStateForProperty();
                return this.mobjParentKey;
            }
        }

        /// <summary>
        /// Returns instance of parent table helper.
        /// </summary>
        public virtual ICommonDBAccess ParentTableHelper
        {
            get
            {
                return (this.mitcParent);
            }
        }

        /// <summary>
        /// Returns parent <see cref="System.Data.DataTable"/>.
        /// </summary>
        /// <exception cref="DBHelper.DataException.BadObjectPropertyAccess">
        /// Instance becomes bad while property being accessed.
        /// </exception>
        public virtual DataTable ParentTable
        {
            get
            {
                this.CheckStateForProperty();
                return this.mobjParentKey.Table;
            }
        }

        /// <summary>
        /// Returns <see cref="System.Data.DataColumn"/> of child keys.
        /// </summary>
        /// <exception cref="DBHelper.DataException.BadObjectPropertyAccess">
        /// Instance becomes bad while property being accessed.
        /// </exception>
        public virtual DataColumn[] ChildColumns
        {
            get
            {
                this.CheckStateForProperty();
                return this.mobjChildKey.Columns;
            }
        }

        /// <summary>
        /// Returns child <see cref="DBHelper.DBKey"/>.
        /// </summary>
        /// <exception cref="DBHelper.DataException.BadObjectPropertyAccess">
        /// Instance becomes bad while property being accessed.
        /// </exception>
        internal virtual DBKey ChildKey
        {
            get
            {
                this.CheckStateForProperty();
                return this.mobjChildKey;
            }
        }

        /// <summary>
        /// Returns instance of child table helper.
        /// </summary>
        public virtual ICommonDBAccess ChildTableHelper
        {
            get
            {
                return (this.mitcChild);
            }
        }

        /// <summary>
        /// Returns child <see cref="System.Data.DataTable"/>.
        /// </summary>
        /// <exception cref="DBHelper.DataException.BadObjectPropertyAccess">
        /// Instance becomes bad while property being accessed.
        /// </exception>
        public virtual DataTable ChildTable
        {
            get
            {
                this.CheckStateForProperty();
                return this.mobjChildKey.Table;
            }
        }

        /// <summary>
        /// Specifies the relationship name.
        /// </summary>
        /// <exception cref="DBHelper.DataException.BadObjectPropertyAccess">
        /// Instance becomes bad while property being accessed.
        /// </exception>
        public virtual string RelationName
        {
            get
            {
                this.CheckStateForProperty();
                return this.mstrRelationName;
            }
            set
            {
                if (value == null)
                {
                    value = "";
                }
                
                this.mstrRelationName = value;
            }
        }
        #endregion
	}
}