// Copyright 2006 - 2008: Rory Plaire (codekaizen@gmail.com)

//

// This file is part of SharpMap.

// SharpMap is free software; you can redistribute it and/or modify

// it under the terms of the GNU Lesser General Public License as published by

// the Free Software Foundation; either version 2 of the License, or

// (at your option) any later version.

//

// SharpMap is distributed in the hope that it will be useful,

// but WITHOUT ANY WARRANTY; without even the implied warranty of

// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the

// GNU Lesser General Public License for more details.

// You should have received a copy of the GNU Lesser General Public License

// along with SharpMap; if not, write to the Free Software

// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA

using System;

using System.Data;

namespace SharpMap.Data.Providers

{

public static class ProviderSchemaHelper

{

public static readonly String ColumnNameColumn = "ColumnName";

public static readonly String ColumnSizeColumn = "ColumnSize";

public static readonly String ColumnOrdinalColumn = "ColumnOrdinal";

public static readonly String NumericPrecisionColumn = "NumericPrecision";

public static readonly String NumericScaleColumn = "NumericScale";

public static readonly String DataTypeColumn = "DataType";

public static readonly String AllowDBNullColumn = "AllowDBNull";

public static readonly String IsReadOnlyColumn = "IsReadOnly";

public static readonly String IsUniqueColumn = "IsUnique";

public static readonly String IsRowVersionColumn = "IsRowVersion";

public static readonly String IsKeyColumn = "IsKey";

public static readonly String IsAutoIncrementColumn = "IsAutoIncrement";

public static readonly String IsLongColumn = "IsLong";

public static readonly String NumericPrecisionExtendedProperty = "Precision";

public static readonly String NumericScaleExtendedProperty = "Scale";

public static readonly String LengthExtendedProperty = "Length";

/// <summary>

/// Creates an empty schema table.

/// </summary>

/// <remarks>

/// <list type="table">

/// <listheader>

/// <term>Column</term>

/// <description>

/// Column in the schema table which describes the column in the data table.

/// </description>

/// </listheader>

/// <item>

/// <term>ColumnName</term>

/// <description>

/// The name of the column; this might not be unique.

/// If the column name cannot be determined, a null value is returned.

/// This name always reflects the most recent naming of the column

/// in the current view or command text.

/// </description>

/// </item>

/// <item>

/// <term>ColumnOrdinal</term>

/// <description>

/// The ordinal of the column. This is zero for the bookmark column of the row, if any.

/// Other columns are numbered starting with 1. This column cannot contain a null value.

/// </description>

/// </item>

/// <item>

/// <term>ColumnSize</term>

/// <description>

/// The maximum possible length of a value in the column.

/// For columns that use a fixed-length data type, this is the size of the data type.

/// </description>

/// </item>

/// <item>

/// <term>NumericPrecision</term>

/// <description>

/// If DbType is a numeric data type, this is the maximum precision of the column.

/// The precision depends on the definition of the column.

/// If DbType is not a numeric data type, this is a null value. If the underlying

/// table has a precision value for a non-numeric data type,

/// this value is used in the schema table.

/// </description>

/// </item>

/// <item>

/// <term>NumericScale</term>

/// <description>

/// If DbType is Decimal, the number of digits to the right of the decimal point.

/// Otherwise, this is a null value. If the underlying table returns a precision

/// value for a non-numeric data type, this value is used in the schema table.

/// </description>

/// </item>

/// <item>

/// <term>DataType</term>

/// <description>

/// Maps to the common language runtime type of DbType.

/// </description>

/// </item>

/// <item>

/// <term>ProviderType</term>

/// <description>

/// The underlying driver type.

/// </description>

/// </item>

/// <item>

/// <term>IsLong</term>

/// <description>

/// <see langword="true"/> if the column holds a large object type, such as

/// a binary large object (BLOB) or character large object (CLOB);

/// <see langword="false"/> if it is a normal value column.

/// </description>

/// </item>

/// <item>

/// <term>AllowDBNull</term>

/// <description>

/// <see langword="true"/> if the consumer can set the column

/// to a null value or if the driver cannot determine whether the

/// consumer can set the column to a null value. Otherwise, <see langword="false"/>.

/// A column may contain null values, even if it cannot be set to a null value.

/// </description>

/// </item>

/// <item>

/// <term>IsReadOnly</term>

/// <description>

/// <see langword="true"/> if the column cannot be modified; otherwise false.

/// </description>

/// </item>

/// <item>

/// <term>IsRowVersion</term>

/// <description>

/// Set if the column contains a persistent row identifier

/// that cannot be written to, and has no meaningful value

/// except to identity the row.

/// </description>

/// </item>

/// <item>

/// <term>IsUnique</term>

/// <description>

/// <para>

/// <see langword="true"/>: No two rows in the base table (the table returned in BaseTableName)

/// can have the same value in this column. IsUnique is guaranteed to be true

/// if the column represents a key by itself or if there is a constraint of

/// type UNIQUE that applies only to this column.

/// </para>

/// <para>

/// <see langword="false"/>: The column can contain duplicate values in the base table.

/// </para>

/// <para>

/// The default for this column is <see langword="false"/>.

/// </para>

/// </description>

/// </item>

/// <item>

/// <term>IsKey</term>

/// <description>

/// <para>

/// <see langword="true"/>: The column is one of a set of columns in the rowset that,

/// taken together, uniquely identify the row. The set of columns with

/// IsKey set to true must uniquely identify a row in the rowset.

/// There is no requirement that this set of columns is a minimal set of columns.

/// This set of columns may be generated from a base table primary key,

/// a unique constraint, or a unique index.

/// </para>

/// <para>

/// <see langword="true"/>: The column is not required to uniquely identify the row.

/// </para>

/// </description>

/// </item>

/// <item>

/// <term>IsAutoIncrement</term>

/// <description>

/// <see langword="true"/> if the column assigns values to new rows in fixed increments; otherwise false.

/// The default for this column is <see langword="false"/>.

/// </description>

/// </item>

/// </list>

/// </remarks>

/// <returns>

/// A <see cref="DataTable"/> with one row per column in the target schema,

/// having a set of columns which describe the target column.

/// </returns>

public static DataTable CreateSchemaTable()

{

DataTable schemaTable = new DataTable();

// all of common, non "base-table" fields implemented

schemaTable.Columns.Add(ColumnNameColumn, typeof(String));

schemaTable.Columns.Add(ColumnSizeColumn, typeof(Int32));

schemaTable.Columns.Add(ColumnOrdinalColumn, typeof(Int32));

schemaTable.Columns.Add(NumericPrecisionColumn, typeof(Int16));

schemaTable.Columns.Add(NumericScaleColumn, typeof(Int16));

schemaTable.Columns.Add(DataTypeColumn, typeof(Type));

schemaTable.Columns.Add(AllowDBNullColumn, typeof(Boolean));

schemaTable.Columns.Add(IsReadOnlyColumn, typeof(Boolean));

schemaTable.Columns.Add(IsUniqueColumn, typeof(Boolean));

schemaTable.Columns.Add(IsRowVersionColumn, typeof(Boolean));

schemaTable.Columns.Add(IsKeyColumn, typeof(Boolean));

schemaTable.Columns.Add(IsAutoIncrementColumn, typeof(Boolean));

schemaTable.Columns.Add(IsLongColumn, typeof(Boolean));

return schemaTable;

}

public static DataTable DeriveSchemaTable(FeatureDataTable table,

ColumnLengthComputationDelegate lengthComputationDelegate,

ColumnPrecisionComputationDelegate precisionComputationDelegate,

ColumnScaleComputationDelegate scaleComputationDelegate)

{

DataTable schema = CreateSchemaTable();

foreach (DataColumn column in table.Columns)

{

DataColumn[] keyColumns = table.PrimaryKey ?? new DataColumn[] { };

Int32 length = column.ExtendedProperties.ContainsKey(LengthExtendedProperty)

? Convert.ToInt32(column.ExtendedProperties[LengthExtendedProperty])

: (lengthComputationDelegate == null) ? 0 : lengthComputationDelegate(column);

Int16 precision = column.ExtendedProperties.ContainsKey(NumericPrecisionExtendedProperty)

? Convert.ToInt16(column.ExtendedProperties[NumericPrecisionExtendedProperty])

: (precisionComputationDelegate == null) ? (Int16)0 : precisionComputationDelegate(column);

Int16 scale = column.ExtendedProperties.ContainsKey(NumericScaleExtendedProperty)

? Convert.ToInt16(column.ExtendedProperties[NumericScaleExtendedProperty])

: (scaleComputationDelegate == null) ? (Int16)0 : scaleComputationDelegate(column);

schema.Rows.Add(

column.ColumnName,

length,

column.Ordinal,

precision,

scale,

column.DataType,

column.AllowDBNull,

column.ReadOnly,

column.Unique,

Array.Exists(keyColumns, delegate(DataColumn col) { return col == column; }),

column.AutoIncrement,

false);

}

return schema;

}

}

}