public override object Execute(Expression expression)
{
var resourceValue = _basePath.Substring(0, _basePath.LastIndexOf('/'));
var translateResult = Translate(expression);
var projector = translateResult.Projector.Compile();
var query = CreateCosmosQueryJson(translateResult.CommandText, null);
var responses = HttpRequestHelper.GetResourceResult("post", _uri, _apiKey, _basePath, resourceValue, query, isQuery: true).Result;
Type type = TypeSystemHelper.GetElementType(expression.Type);
var list = (IList)Activator.CreateInstance(typeof(List <>).MakeGenericType(type));
var serializationType = typeof(IEnumerable <>).MakeGenericType(type);
foreach (var response in responses)
{
if (response.StatusCode != HttpStatusCode.OK)
{
throw new CosmosQueryException(response.Body);
}
var cosmosQueryResponse = _serializer.Deserailize <CosmosQueryResponse>(response.Body);
var items = _serializer.Deserialize(cosmosQueryResponse.Documents.ToString(), serializationType);
foreach (var item in (ICollection)items)
{
list.Add(item);
}
}
return(list);
}
public IQueryable CreateQuery(Expression expression)
{
var elementType = TypeSystemHelper.GetElementType(expression.Type);
try
{
return((IQueryable)Activator.CreateInstance(typeof(CosmosQueryable <>).MakeGenericType(elementType), new object[] { this, expression }));
}
catch (TargetInvocationException tie)
{
throw tie.InnerException;
}
}
/// <summary>
/// Add the expression (x => _type == "Type.FullName" to the expression tree.
/// </summary>
/// <param name="expression"></param>
/// <returns></returns>
internal static Expression Inject(Expression expression)
{
var type = TypeSystemHelper.GetElementType(expression.Type);
var targetExpression = Expression.Parameter(type, "x");
var namespaceExpression = Expression.Constant(type.FullName);
var stellerTypeExpression = Expression.Constant("_type");
var equalExp = Expression.Equal(stellerTypeExpression, namespaceExpression);
var queryableType = typeof(Queryable);
var whereMethod = queryableType.GetMethods().First(m =>
{
var parameters = m.GetParameters().ToList();
return(m.Name == "Where" && m.IsGenericMethodDefinition && parameters.Count == 2);
});
var whereClause = Expression.Lambda(equalExp, new ParameterExpression[] { targetExpression });
var genericMethod = whereMethod.MakeGenericMethod(type);
var exp = Expression.Call(genericMethod, expression, whereClause);
return(exp);
}
