Merge pull request #17 from dgraph-io/aman/add_order_to_rules

chore: adding order to the validation rules

Author: aman-bansal

validator/validator.go

@@ -1,6 +1,8 @@
 package validator
 
 import (
+	"sort"
+
 	. "github.com/dgraph-io/gqlparser/v2/ast"
 	"github.com/dgraph-io/gqlparser/v2/gqlerror"
 )
@@ -11,7 +13,9 @@ type ruleFunc func(observers *Events, addError AddErrFunc)
 
 type rule struct {
 	name string
-	rule ruleFunc
+	// rules will be called in the ascending order
+	order int
+	rule  ruleFunc
 }
 
 var rules []rule
@@ -22,10 +26,19 @@ func AddRule(name string, f ruleFunc) {
 	rules = append(rules, rule{name: name, rule: f})
 }
 
+// AddRuleWithOrder to rule set with an order.
+// f is called once each time `Validate` is executed.
+func AddRuleWithOrder(name string, order int, f ruleFunc) {
+	rules = append(rules, rule{name: name, order: order, rule: f})
+}
+
 func Validate(schema *Schema, doc *QueryDocument, variables map[string]interface{}) gqlerror.List {
 	var errs gqlerror.List
 
 	observers := &Events{}
+	sort.Slice(rules, func(i, j int) bool {
+		return rules[i].order < rules[j].order
+	})
 	for i := range rules {
 		rule := rules[i]
 		rule.rule(observers, func(options ...ErrorOption) {