public static TableOperation Retrieve <TElement>(string partitionKey, string rowkey, List <string> selectColumns = null)
where TElement : ITableEntity
{
CommonUtility.AssertNotNull("partitionKey", partitionKey);
CommonUtility.AssertNotNull("rowkey", rowkey);
// Create and return the table operation.
return(new TableOperation(null /* entity */, TableOperationType.Retrieve)
{
RetrievePartitionKey = partitionKey,
RetrieveRowKey = rowkey,
SelectColumns = selectColumns,
RetrieveResolver =
(pk, rk, ts, prop, etag) => EntityUtilities.ResolveEntityByType <TElement>(
pk,
rk,
ts,
prop,
etag),
PropertyResolverType = typeof(TElement)
});
}
internal ExecutionInfo Bind()
{
ExecutionInfo retVal = new ExecutionInfo();
// IQueryable impl
if (this.Expression != null)
{
Dictionary <Expression, Expression> normalizerRewrites = new Dictionary <Expression, Expression>(ReferenceEqualityComparer <Expression> .Instance);
// Step 1. Evaluate any local evaluatable expressions ( lambdas etc)
Expression partialEvaluatedExpression = Evaluator.PartialEval(this.Expression);
// Step 2. Normalize expression, replace String Comparisons etc.
Expression normalizedExpression = ExpressionNormalizer.Normalize(partialEvaluatedExpression, normalizerRewrites);
// Step 3. Bind Expression, Analyze predicates and create query option expressions. End result is a single ResourceSetExpression
Expression boundExpression = ResourceBinder.Bind(normalizedExpression);
// Step 4. Parse the Bound expression into sub components, i.e. take count, filter, select columns, request options, opcontext, etc.
ExpressionParser parser = new ExpressionParser();
parser.Translate(boundExpression);
// Step 5. Store query components & params
this.TakeCount = parser.TakeCount;
this.FilterString = parser.FilterString;
this.SelectColumns = parser.SelectColumns;
retVal.RequestOptions = parser.RequestOptions;
retVal.OperationContext = parser.OperationContext;
// Step 6. If projection & no resolver then generate a resolver to perform the projection
if (parser.Resolver == null)
{
if (parser.Projection != null && parser.Projection.Selector != ProjectionQueryOptionExpression.DefaultLambda)
{
Type intermediateType = parser.Projection.Selector.Parameters[0].Type;
// Convert Expression to take type object as input to allow for direct invocation.
ParameterExpression paramExpr = Expression.Parameter(typeof(object));
Func <object, TElement> projectorFunc = Expression.Lambda <Func <object, TElement> >(
Expression.Invoke(parser.Projection.Selector, Expression.Convert(paramExpr, intermediateType)), paramExpr).Compile();
// Generate a resolver to do the projection.
retVal.Resolver = (pk, rk, ts, props, etag) =>
{
// Parse to intermediate type
ITableEntity intermediateObject = (ITableEntity)EntityUtilities.InstantiateEntityFromType(intermediateType);
intermediateObject.PartitionKey = pk;
intermediateObject.RowKey = rk;
intermediateObject.Timestamp = ts;
intermediateObject.ReadEntity(props, parser.OperationContext);
intermediateObject.ETag = etag;
// Invoke lambda expression
return(projectorFunc(intermediateObject));
};
}
else
{
// No op - No resolver or projection specified.
}
}
else
{
retVal.Resolver = (EntityResolver <TElement>)parser.Resolver.Value;
}
}
retVal.RequestOptions = TableRequestOptions.ApplyDefaults(retVal.RequestOptions, this.queryProvider.Table.ServiceClient);
retVal.OperationContext = retVal.OperationContext ?? new OperationContext();
return(retVal);
}
public void Retrieve <TElement>(string partitionKey, string rowKey, List <string> selectedColumns = null) where TElement : ITableEntity
{
CommonUtility.AssertNotNull("partitionKey", partitionKey);
CommonUtility.AssertNotNull("rowkey", rowKey);
// Add the table operation.
this.Add(new TableOperation(null /* entity */, TableOperationType.Retrieve)
{
RetrievePartitionKey = partitionKey, RetrieveRowKey = rowKey, SelectColumns = selectedColumns, RetrieveResolver = (pk, rk, ts, prop, etag) => EntityUtilities.ResolveEntityByType <TElement>(pk, rk, ts, prop, etag)
});
}