relay connection working with gqlgen

1 files changed, 224 insertions, 0 deletions

diff --git a/graphql2/resolvers/pagers_template.go b/graphql2/resolvers/pagers_template.go
new file mode 100644
index 00000000..0ca7de75
--- /dev/null
+++ b/graphql2/resolvers/pagers_template.go
@@ -0,0 +1,224 @@
+package resolvers
+
+import (
+	"fmt"
+	"github.com/cheekybits/genny/generic"
+)
+
+type NodeType generic.Type
+type EdgeType generic.Type
+
+type NodeTypeEdger func(value NodeType, offset int) Edge
+
+func NodeTypePaginate(source []NodeType, edger NodeTypeEdger, input ConnectionInput) ([]EdgeType, PageInfo, error) {
+	var result []EdgeType
+	var pageInfo PageInfo
+
+	offset := 0
+
+	if input.After != nil {
+		for i, value := range source {
+			edge := edger(value, i)
+			if edge.GetCursor() == *input.After {
+				// remove all previous element including the "after" one
+				source = source[i+1:]
+				offset = i + 1
+				break
+			}
+		}
+	}
+
+	if input.Before != nil {
+		for i, value := range source {
+			edge := edger(value, i+offset)
+
+			if edge.GetCursor() == *input.Before {
+				// remove all after element including the "before" one
+				break
+			}
+
+			result = append(result, edge.(EdgeType))
+		}
+	} else {
+		result = make([]EdgeType, len(source))
+
+		for i, value := range source {
+			result[i] = edger(value, i+offset).(EdgeType)
+		}
+	}
+
+	if input.First != nil {
+		if *input.First < 0 {
+			return nil, PageInfo{}, fmt.Errorf("first less than zero")
+		}
+
+		if len(result) > *input.First {
+			// Slice result to be of length first by removing edges from the end
+			result = result[:*input.First]
+			pageInfo.HasNextPage = true
+		}
+	}
+
+	if input.Last != nil {
+		if *input.Last < 0 {
+			return nil, PageInfo{}, fmt.Errorf("last less than zero")
+		}
+
+		if len(result) > *input.Last {
+			// Slice result to be of length last by removing edges from the start
+			result = result[len(result)-*input.Last:]
+			pageInfo.HasPreviousPage = true
+		}
+	}
+
+	return result, pageInfo, nil
+}
+
+// Apply the before/after cursor params to the source and return an array of edges
+//func ApplyCursorToEdges(source []interface{}, edger Edger, input ConnectionInput) []Edge {
+//	var result []Edge
+//
+//	if input.After != nil {
+//		for i, value := range source {
+//			edge := edger(value)
+//			if edge.Cursor() == *input.After {
+//				// remove all previous element including the "after" one
+//				source = source[i+1:]
+//				break
+//			}
+//		}
+//	}
+//
+//	if input.Before != nil {
+//		for _, value := range source {
+//			edge := edger(value)
+//
+//			if edge.Cursor() == *input.Before {
+//				// remove all after element including the "before" one
+//				break
+//			}
+//
+//			result = append(result, edge)
+//		}
+//	} else {
+//		result = make([]Edge, len(source))
+//
+//		for i, value := range source {
+//			result[i] = edger(value)
+//		}
+//	}
+//
+//	return result
+//}
+
+// Apply the first/last cursor params to the edges
+//func EdgesToReturn(edges []Edge, input ConnectionInput) ([]Edge, PageInfo, error) {
+//	hasPreviousPage := false
+//	hasNextPage := false
+//
+//	if input.First != nil {
+//		if *input.First < 0 {
+//			return nil, nil, fmt.Errorf("first less than zero")
+//		}
+//
+//		if len(edges) > *input.First {
+//			// Slice result to be of length first by removing edges from the end
+//			edges = edges[:*input.First]
+//			hasNextPage = true
+//		}
+//	}
+//
+//	if input.Last != nil {
+//		if *input.Last < 0 {
+//			return nil, nil, fmt.Errorf("last less than zero")
+//		}
+//
+//		if len(edges) > *input.Last {
+//			// Slice result to be of length last by removing edges from the start
+//			edges = edges[len(edges)-*input.Last:]
+//			hasPreviousPage = true
+//		}
+//	}
+//
+//	pageInfo := PageInfo{
+//		HasNextPage:     hasNextPage,
+//		HasPreviousPage: hasPreviousPage,
+//	}
+//
+//	return edges, pageInfo, nil
+//}
+
+//func EdgesToReturn(allEdges []Edge, before *cursor, after *cursor, first *int, last *int) ([]Edge, error) {
+//	result := ApplyCursorToEdges(allEdges, before, after)
+//
+//	if first != nil {
+//		if *first < 0 {
+//			return nil, fmt.Errorf("first less than zero")
+//		}
+//
+//		if len(result) > *first {
+//			// Slice result to be of length first by removing edges from the end
+//			result = result[:*first]
+//		}
+//	}
+//
+//	if last != nil {
+//		if *last < 0 {
+//			return nil, fmt.Errorf("last less than zero")
+//		}
+//
+//		if len(result) > *last {
+//			// Slice result to be of length last by removing edges from the start
+//			result = result[len(result)-*last:]
+//		}
+//	}
+//
+//	return result, nil
+//}
+
+//func ApplyCursorToEdges(allEdges []Edge, before *cursor, after *cursor) []Edge {
+//	result := allEdges
+//
+//	if after != nil {
+//		for i, edge := range result {
+//			if edge.Cursor() == *after {
+//				// remove all previous element including the "after" one
+//				result = result[i+1:]
+//				break
+//			}
+//		}
+//	}
+//
+//	if before != nil {
+//		for i, edge := range result {
+//			if edge.Cursor() == *before {
+//				// remove all after element including the "before" one
+//				result = result[:i]
+//			}
+//		}
+//	}
+//
+//	return result
+//}
+
+//func HasPreviousPage(allEdges []Edge, before *cursor, after *cursor, last *int) bool {
+//	if last != nil {
+//		edges := ApplyCursorToEdges(allEdges, before, after)
+//		return len(edges) > *last
+//	}
+//
+//	// TODO: handle "after", but according to the spec it's ok to return false
+//
+//	return false
+//}
+//
+//func HasNextPage(allEdges []Edge, before *cursor, after *cursor, first *int) bool {
+//	if first != nil {
+//		edges := ApplyCursorToEdges(allEdges, before, after)
+//		return len(edges) > *first
+//	}
+//
+//	// TODO: handle "before", but according to the spec it's ok to return false
+//
+//	return false
+//}