feat: add pagination validation

firestore.go

@@ -37,20 +37,6 @@ func SuffixCollection(c string) string {
 	return fmt.Sprintf("%v_bewell_%v", c, GetFirestoreEnvironmentSuffix())
 }
 
-// ValidatePaginationParameters ensures that the supplied pagination parameters make sense
-func ValidatePaginationParameters(pagination *PaginationInput) error {
-	if pagination == nil {
-		return nil // not having pagination is not a fatal error
-	}
-
-	// if `first` is specified, `last` cannot be specified
-	if pagination.First > 0 && pagination.Last > 0 {
-		return fmt.Errorf("if `first` is specified for pagination, `last` cannot be specified")
-	}
-
-	return nil
-}
-
 // OpString translates between an Operation enum value and the appropriate firestore
 // query operator
 func OpString(op enumutils.Operation) (string, error) {
@@ -165,16 +151,16 @@ func QueryNodes(
 	// pagination
 	pageSize := DefaultPageSize
 	if pagination != nil {
-		if pagination.First > 0 {
+		if pagination.First != nil {
 			if pagination.After != "" {
-				query = query.OrderBy("id", firestore.Asc).StartAfter(pagination.After).Limit(pagination.First)
+				query = query.OrderBy("id", firestore.Asc).StartAfter(pagination.After).Limit(*pagination.First)
 			}
-			pageSize = pagination.First
+			pageSize = *pagination.First
 			query = query.Limit(pageSize)
 		}
-		if pagination.Last > 0 {
+		if pagination.Last != nil {
 			if pagination.Before != "" {
-				query = query.OrderBy("id", firestore.Asc).EndAt(pagination.Before).LimitToLast(pagination.Last)
+				query = query.OrderBy("id", firestore.Asc).EndAt(pagination.Before).LimitToLast(*pagination.Last)
 			}
 		}
 	}

firestore_test.go

@@ -56,46 +56,42 @@ func Test_validatePaginationParameters(t *testing.T) {
 	}{
 		"first_last_specified": {
 			pagination: &fb.PaginationInput{
-				First: first,
-				Last:  last,
+				First: &first,
+				Last:  &last,
 			},
 			expectError:          true,
-			expectedErrorMessage: "if `first` is specified for pagination, `last` cannot be specified",
+			expectedErrorMessage: "cannot provide both first and last",
 		},
 		"first_only": {
 			pagination: &fb.PaginationInput{
-				First: first,
+				First: &first,
 			},
 			expectError: false,
 		},
 		"last_only": {
 			pagination: &fb.PaginationInput{
-				Last: last,
+				Last: &last,
 			},
 			expectError: false,
 		},
 		"first_and_after": {
 			pagination: &fb.PaginationInput{
-				First: first,
+				First: &first,
 				After: after,
 			},
 			expectError: false,
 		},
 		"last_and_before": {
 			pagination: &fb.PaginationInput{
-				Last:   last,
+				Last:   &last,
 				Before: before,
 			},
 			expectError: false,
 		},
-		"nil_pagination": {
-			pagination:  nil,
-			expectError: false,
-		},
 	}
 	for name, tc := range tests {
 		t.Run(name, func(t *testing.T) {
-			err := fb.ValidatePaginationParameters(tc.pagination)
+			err := tc.pagination.Validate()
 			if tc.expectError {
 				assert.NotNil(t, err)
 				assert.Contains(t, err.Error(), tc.expectedErrorMessage)
@@ -609,6 +605,9 @@ func TestRetrieveNode(t *testing.T) {
 }
 
 func TestQueryNodes(t *testing.T) {
+	first := 10
+	last := 1
+
 	ctx := context.Background()
 	node := &fb.Model{
 		Name:        "test model instance",
@@ -657,7 +656,7 @@ func TestQueryNodes(t *testing.T) {
 			args: args{
 				ctx: ctx,
 				pagination: &fb.PaginationInput{
-					First: 10,
+					First: &first,
 					After: id,
 				},
 				filter: nil,
@@ -671,7 +670,7 @@ func TestQueryNodes(t *testing.T) {
 			args: args{
 				ctx: ctx,
 				pagination: &fb.PaginationInput{
-					Last:   1,
+					Last:   &last,
 					Before: id,
 				},
 				filter: nil,

helpers.go

@@ -76,11 +76,16 @@ func GetAPIPaginationParams(pagination *PaginationInput) (url.Values, error) {
 	// `first` will supersede `last`
 	var err error
 	pageSize := DefaultRESTAPIPageSize
-	if pagination.Last > 0 {
-		pageSize = pagination.Last
+
+	err = pagination.Validate()
+	if err != nil {
+		return url.Values{}, nil
 	}
-	if pagination.First > 0 {
-		pageSize = pagination.First
+
+	if pagination.Last != nil {
+		pageSize = *pagination.Last
+	} else if pagination.First != nil {
+		pageSize = *pagination.First
 	}
 
 	// For these "pass through APIs", "after" and "before" should be parseable as ints

model.go

@@ -11,28 +11,57 @@ import (
 	"github.com/savannahghi/enumutils"
 )
 
+const defaultPageCount = 10
+
 // QueryParam is an interface used for filter and sort parameters
 type QueryParam interface {
 	ToURLValues() (values url.Values)
 }
 
 // PaginationInput represents paging parameters
 type PaginationInput struct {
-	First  int    `json:"first"`
-	Last   int    `json:"last"`
+	First  *int   `json:"first"`
+	Last   *int   `json:"last"`
 	After  string `json:"after"`
 	Before string `json:"before"`
 }
 
-//IsEntity ...
+// IsEntity ...
 func (p PaginationInput) IsEntity() {}
 
+func (p *PaginationInput) Validate() error {
+	if p.First != nil && p.Last != nil {
+		return fmt.Errorf("cannot provide both first and last")
+	}
+
+	if p.First != nil {
+		first := *p.First
+		if first <= 0 {
+			return fmt.Errorf("first cannot be less than 0")
+		}
+	}
+
+	if p.Last != nil {
+		last := *p.Last
+		if last <= 0 {
+			return fmt.Errorf("last cannot be less than 0")
+		}
+	}
+
+	if p.First == nil && p.Last == nil {
+		limit := defaultPageCount
+		p.First = &limit
+	}
+
+	return nil
+}
+
 // SortInput is a generic container for strongly typed sorting parameters
 type SortInput struct {
 	SortBy []*SortParam `json:"sortBy"`
 }
 
-//IsEntity ...
+// IsEntity ...
 func (s SortInput) IsEntity() {}
 
 // SortParam represents a single field sort parameter
@@ -41,7 +70,7 @@ type SortParam struct {
 	SortOrder enumutils.SortOrder `json:"sortOrder"`
 }
 
-//IsEntity ...
+// IsEntity ...
 func (s SortParam) IsEntity() {}
 
 // FilterInput is s generic container for strongly type filter parameters
@@ -50,7 +79,7 @@ type FilterInput struct {
 	FilterBy []*FilterParam `json:"filterBy"`
 }
 
-//IsEntity ...
+// IsEntity ...
 func (f FilterInput) IsEntity() {}
 
 // FilterParam represents a single field filter parameter
@@ -61,7 +90,7 @@ type FilterParam struct {
 	FieldValue          interface{}         `json:"fieldValue"`
 }
 
-//IsEntity ...
+// IsEntity ...
 func (f FilterParam) IsEntity() {}
 
 // FirebaseRefreshResponse is used to (de)serialize the results of a successful Firebase token refresh
@@ -114,7 +143,7 @@ type PageInfo struct {
 	EndCursor       *string `json:"endCursor"`
 }
 
-//IsEntity ...
+// IsEntity ...
 func (p PageInfo) IsEntity() {}
 
 // NewString returns a pointer to the supplied string.
@@ -170,7 +199,7 @@ func (c *Model) SetID(id string) {
 	c.ID = id
 }
 
-//IsEntity ...
+// IsEntity ...
 func (c Model) IsEntity() {}
 
 // LoginResponse is used to (de)serialize the result of a successful login