public PaginationDto <TreeDto> GetTrees(long page, long pageSize, string sort, Contracts.SortDirection sortDir)
{
var pipeline = GetPaginatedTreesAggregation(page, pageSize, sort, sortDir);
var result = _treesCollections.Aggregate <BsonDocument>(pipeline).ToList();
var count = result[0]["total"][0]["count"].ToInt32();
var trees = result[0]["results"].AsBsonArray
.Select(b => BsonSerializer.Deserialize <TreeEntity>(b.AsBsonDocument).ToDto())
.ToArray();
return(new PaginationDto <TreeDto>(
page: page,
pageSize: pageSize,
sort: sort,
sortDir: sortDir.ToString().ToLower(),
count: count,
items: trees));
}
private BsonDocument[] GetPaginatedTreesAggregation(long page, long pageSize, string sort, Contracts.SortDirection sortDir)
{
var sortStep = new BsonDocument()
{
{ "$sort", new BsonDocument {
{ sort, sortDir == Contracts.SortDirection.Asc ? 1 : -1 }
} }
};
var resultsFacetStep = new BsonArray(new[]
{
new BsonDocument()
{
{ "$skip", page * pageSize }
},
new BsonDocument()
{
{ "$limit", pageSize }
},
});
var totalFacetStep = new BsonArray(new[]
{
new BsonDocument()
{
{ "$count", "count" }
},
});
var facetStep = new BsonDocument()
{
{ "$facet", new BsonDocument()
{
{ "results", resultsFacetStep },
{ "total", totalFacetStep },
} }
};
var pipeline = new[] { sortStep, facetStep };
return(pipeline);
}
