Method extractRequiredFieldsData

query/outputnode_graphql.go:533–575

extractRequiredFieldsData is used to extract the data of fields which are required to resolve a custom field from a given parentNode. It returns a map containing the extracted data along with the dgraph.type values for parentNode. The keys in the returned map correspond to the name of a required fie

(parentNode fastJsonNode,
	rfDefs map[string]gqlSchema.FieldDefinition)

// The keys in the returned map correspond to the name of a required field.
// Values in the map correspond to the extracted data for a required field.
func (genc *graphQLEncoder) extractRequiredFieldsData(parentNode fastJsonNode,
	rfDefs map[string]gqlSchema.FieldDefinition) (map[string]interface{}, []string) {
	child := genc.children(parentNode)
	// first, just skip all the custom nodes
	for ; child != nil && genc.getCustom(child); child = child.next {
		// do nothing
	}
	// then, extract data for dgraph.type
	child, dgraphTypes := genc.extractDgraphTypes(child)

	// now, iterate over rest of the children of the parentNode and find out the data for
	// requiredFields. We can stop iterating as soon as we have the data for all the requiredFields.
	rfData := make(map[string]interface{})
	for fj := child; fj != nil && len(rfData) < len(rfDefs); fj = fj.next {
		// check if this node has the data for a requiredField. If yes, we need to
		// extract that in the rfData map to be used later in substitution.
		if rfDef := rfDefs[genc.attrForID(genc.getAttr(fj))]; rfDef != nil {
			// if the requiredField is of list type, then need to extract all the data for the list.
			// using enc.getList() instead of `rfDef.Type().ListType() != nil` as for custom fields
			// both have the same behaviour and enc.getList() is fast.
			if genc.getList(fj) {
				var vals []interface{}
				for ; fj.next != nil && genc.getAttr(fj.next) == genc.getAttr(fj); fj = fj.next {
					if val, err := genc.getScalarVal(fj); err == nil {
						vals = append(vals, json.RawMessage(val))
					}
				}
				// append the last list value
				if val, err := genc.getScalarVal(fj); err == nil {
					vals = append(vals, json.RawMessage(val))
				}
				rfData[rfDef.Name()] = vals
			} else {
				// this requiredField is of non-list type, need to extract the only
				// data point for this.
				if val, err := genc.getScalarVal(fj); err == nil {
					rfData[rfDef.Name()] = json.RawMessage(val)
				}
			}
		}
	}
	return rfData, dgraphTypes
}

// writeCustomField is used to write the value when the currentSelection is a custom field.
// If the current field had @custom(http: {...}), then we need to find the fastJson node which