Add table and view metadata messges (#296)

* Add SMO table property lookup event

* Fix a couple bugs in column metadata

* Add GetView metadata message

src/Microsoft.SqlTools.ServiceLayer/Metadata/Contracts/ColumnMetadata.cs

@@ -0,0 +1,112 @@
+//
+// Copyright (c) Microsoft. All rights reserved.
+// Licensed under the MIT license. See LICENSE file in the project root for full license information.
+//
+
+using System.Data;
+using Microsoft.SqlTools.ServiceLayer.QueryExecution.Contracts;
+using Microsoft.SqlTools.Utility;
+
+namespace Microsoft.SqlTools.ServiceLayer.Metadata
+{
+    /// <summary>
+    /// ColumnMetadata class
+    /// </summary>
+    public class ColumnMetadata
+    {
+        /// <summary>
+        /// Constructs a simple edit column metadata provider
+        /// </summary>
+        public ColumnMetadata()
+        {
+            HasExtendedProperties = false;
+        }
+
+        #region Basic Properties (properties provided by SMO)
+
+        /// <summary>
+        /// If set, this is a string representation of the default value. If set to null, then the
+        /// column does not have a default value.
+        /// </summary>
+        public string DefaultValue { get; set; }
+
+        /// <summary>
+        /// Escaped identifier for the name of the column
+        /// </summary>
+        public string EscapedName { get; set; }
+
+        /// <summary>
+        /// Whether or not the column is computed
+        /// </summary>
+        public bool IsComputed { get; set; }
+
+        /// <summary>
+        /// Whether or not the column is deterministically computed
+        /// </summary>
+        public bool IsDeterministic { get; set; }
+
+        /// <summary>
+        /// Whether or not the column is an identity column
+        /// </summary>
+        public bool IsIdentity { get; set; }
+
+        /// <summary>
+        /// The ordinal ID of the column
+        /// </summary>
+        public int Ordinal { get; set; }
+
+        #endregion
+
+        #region Extended Properties (properties provided by SqlClient)
+
+        // public DbColumnWrapper DbColumn { get; private set; }
+
+        /// <summary>
+        /// Whether or not the column has extended properties
+        /// </summary>
+        public bool HasExtendedProperties { get; private set; }
+
+        /// <summary>
+        /// Whether or not the column is calculated on the server side. This could be a computed
+        /// column or a identity column.
+        /// </summary>
+        public bool? IsCalculated { get; private set; }
+
+        /// <summary>
+        /// Whether or not the column is used in a key to uniquely identify a row
+        /// </summary>
+        public bool? IsKey { get; private set; }
+
+        /// <summary>
+        /// Whether or not the column can be trusted for uniqueness
+        /// </summary>
+        public bool? IsTrustworthyForUniqueness { get; private set; }
+
+        #endregion
+
+        /// <summary>
+        /// Extracts extended column properties from the database columns from SQL Client
+        /// </summary>
+        /// <param name="dbColumn">The column information provided by SQL Client</param>
+        public void Extend(DbColumnWrapper dbColumn)
+        {
+            Validate.IsNotNull(nameof(dbColumn), dbColumn);
+
+            // DbColumn = dbColumn;
+
+            // A column is trustworthy for uniqueness if it can be updated or it has an identity
+            // property. If both of these are false (eg, timestamp) we can't trust it to uniquely
+            // identify a row in the table
+            IsTrustworthyForUniqueness = dbColumn.IsUpdatable || dbColumn.IsIdentity.HasTrue();
+
+            // A key column is determined by whether it is a key
+            IsKey = dbColumn.IsKey;
+
+            // A column is calculated if it is identity, computed, or otherwise not updatable
+            IsCalculated = IsIdentity || IsComputed || !dbColumn.IsUpdatable;
+
+            // Mark the column as extended
+            HasExtendedProperties = true;
+        }
+    }
+}

src/Microsoft.SqlTools.ServiceLayer/Metadata/Contracts/TableMetadata.cs

@@ -0,0 +1,85 @@
+//
+// Copyright (c) Microsoft. All rights reserved.
+// Licensed under the MIT license. See LICENSE file in the project root for full license information.
+//
+
+using System.Linq;
+using Microsoft.SqlTools.ServiceLayer.QueryExecution.Contracts;
+using Microsoft.SqlTools.Utility;
+
+namespace Microsoft.SqlTools.ServiceLayer.Metadata
+{
+    /// <summary>
+    /// Provides metadata about the table or view being edited
+    /// </summary>
+    public class TableMetadata
+    {
+        /// <summary>
+        /// Constructs a simple edit table metadata provider
+        /// </summary>
+        public TableMetadata()
+        {
+            HasExtendedProperties = false;
+        }
+
+        #region Basic Properties (properties provided by SMO)
+
+        /// <summary>
+        /// List of columns in the object being edited
+        /// </summary>
+        public ColumnMetadata[] Columns { get; set; }
+
+        /// <summary>
+        /// Full escaped multipart identifier for the object being edited
+        /// </summary>
+        public string EscapedMultipartName { get; set; }
+
+        /// <summary>
+        /// Whether or not the object being edited is memory optimized
+        /// </summary>
+        public bool IsMemoryOptimized { get; set; }
+
+        #endregion
+
+        #region Extended Properties (properties provided by SqlClient)
+
+        /// <summary>
+        /// Whether or not the table has had extended properties added to it
+        /// </summary>
+        public bool HasExtendedProperties { get; private set; }
+
+        /// <summary>
+        /// List of columns that are used to uniquely identify a row
+        /// </summary>
+        public ColumnMetadata[] KeyColumns { get; private set; }
+
+        #endregion
+
+        /// <summary>
+        /// Extracts extended column properties from the database columns from SQL Client
+        /// </summary>
+        /// <param name="dbColumnWrappers">The column information provided by SQL Client</param>
+        public void Extend(DbColumnWrapper[] dbColumnWrappers)
+        {
+            Validate.IsNotNull(nameof(dbColumnWrappers), dbColumnWrappers);
+
+            // Iterate over the column wrappers and improve the columns we have
+            for (int i = 0; i < Columns.Length; i++)
+            {
+                Columns[i].Extend(dbColumnWrappers[i]);
+            }
+
+            // Determine what the key columns are
+            KeyColumns = Columns.Where(c => c.IsKey.HasTrue()).ToArray();
+            if (KeyColumns.Length == 0)
+            {
+                // We didn't find any explicit key columns. Instead, we'll use all columns that are
+                // trustworthy for uniqueness (usually all the columns)
+                KeyColumns = Columns.Where(c => c.IsTrustworthyForUniqueness.HasTrue()).ToArray();
+            }
+
+            // Mark that the table is now extended
+            HasExtendedProperties = true;
+        }
+    }
+}

src/Microsoft.SqlTools.ServiceLayer/Metadata/Contracts/TableMetadataRequest.cs

@@ -0,0 +1,33 @@
+//
+// Copyright (c) Microsoft. All rights reserved.
+// Licensed under the MIT license. See LICENSE file in the project root for full license information.
+//
+
+using Microsoft.SqlTools.Hosting.Protocol.Contracts;
+
+namespace Microsoft.SqlTools.ServiceLayer.Metadata.Contracts
+{
+    public class TableMetadataParams 
+    {
+        public string OwnerUri { get; set; }        
+
+        public string Schema { get; set; }  
+
+        public string ObjectName { get; set; }  
+    }
+
+    public class TableMetadataResult
+    {
+        public ColumnMetadata[] Columns { get; set; }
+    }
+
+    /// <summary>
+    /// Retreive metadata for the table described in the TableMetadataParams value
+    /// </summary>
+    public class TableMetadataRequest
+    {
+        public static readonly
+            RequestType<TableMetadataParams, TableMetadataResult> Type =
+                RequestType<TableMetadataParams, TableMetadataResult>.Create("metadata/table");
+    }
+}

src/Microsoft.SqlTools.ServiceLayer/Metadata/Contracts/ViewMetadataRequest.cs

@@ -0,0 +1,21 @@
+//
+// Copyright (c) Microsoft. All rights reserved.
+// Licensed under the MIT license. See LICENSE file in the project root for full license information.
+//
+
+using Microsoft.SqlTools.Hosting.Protocol.Contracts;
+
+namespace Microsoft.SqlTools.ServiceLayer.Metadata.Contracts
+{
+    /// <summary>
+    /// Retreive metadata for the view described in the TableMetadataParams value.
+    /// This message reuses the table metadata params and result since the exchanged
+    /// data is the same.
+    /// </summary>
+    public class ViewMetadataRequest
+    {
+        public static readonly
+            RequestType<TableMetadataParams, TableMetadataResult> Type =
+                RequestType<TableMetadataParams, TableMetadataResult>.Create("metadata/view");
+    }
+}