Relay Fragment Optional Arguments - relay

Question

Is it possible to optionally include parameters when creating a Relay query?
See below I'm querying resources, and I'm hard coding the params here.
I would like to conditionally include some of these arguments, for example date_gt and date_lt. At the moment I have to set initial values for these, but that falls apart as I need to query for records without dates at all.
If I can't do that is it possible to send null as a value to a param here because I'm not having much luck with that either at the moment.
fragments: {
viewer: () => Relay.QL`
fragment on Viewer {
resources(
first: $pageSize
q: $q
type: $types
license: $licenses
order: $order
access_rights: "published"
orphan: true
date_gt: $dateFrom
date_lt: $dateTo
)
{
total
edges {
node {
${ArticleResult.getFragment('resource')}
}
}
pageInfo {
hasNextPage
}
}
}
`
},

Answer 1

Yes, we can provide null as the value for an optional argument in Relay (client-side).
However, we can also provide default values for those optional arguments. For example, in the GraphQL schema, the field resources can be like:
resources: {
type: ResourceConnection,
args: {
// other args go here
date_gt: {
type: GraphQLString,
defaultValue: '1970-01-01'
},
date_lt: {
type: GraphQLString,
defaultValue: '2030-12-31'
},
...connectionArgs
},
resolve: async (root, {...otherArgs, date_gt, date_lt, ...args}) => {
// Check date_gt and/or date_lt values. If they equal the default
// invalid values, ignore them while calculating output. Sometimes it
// is possible that the default values are good enough to be equivalent
// of user-provided values.
return output;
},
},
If we do not provide a default value for an optional argument, we can set value of the optional argument to null. In that case, undefined value is received on the server side:
resources: {
type: ResourceConnection,
args: {
// other args go here
date_gt: {
type: GraphQLString,
},
date_lt: {
type: GraphQLString,
},
...connectionArgs
},
resolve: async (root, {...otherArgs, date_gt, date_lt, ...args}) => {
console.log(`date_gt: ${date_gt}, date_lt: ${date_lt}`);
// Check date_gt and/or date_lt values. If they are not provided,
// date_gt and date_lt are `undefined`. Calculate output accordingly.
return output;
},
},