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Relay-Pagination-example.md
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Relay-Pagination-example.md
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For this example, we're using `DjangoObjectType` and a hypothetical django model for Place. Neither of these is necessary, and it's being included only to present a complete (almost) example. Simply replace the model assignment, and use the appropriate `ObjectType` in place of `DjangoObjectType` in the initial type declaration (`class Place_Node_Type(DjangoObjectType)` herein) for your application, and pagination will be yours!
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For this example, we're going to assume a basic understanding of what `startCursor` and `endCursor`, and really, `pagination` as a concept, actually **are**, and just quickly provide you with the basics of pagination-in-graphene's **how**.
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In a nutshell, `pagination` is implemented via graphene relay's `Connection` and `ConnectionField` pairing. With these in place, you'll see `pageInfo` available within your queries. It looks something like this:
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```
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"pageInfo": {
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"startCursor": "YXJyYXljb25uZWN0aW9uOjQx",
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"endCursor": "YXJyYXljb25uZWN0aW9uOjQz",
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"hasNextPage": false,
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"hasPreviousPage": true
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},
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```
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In addition to a `cursor` element within `edges` that will show you the cursor id for each element, like so:
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```
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edges {
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cursor
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node {
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<whatever>
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}
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}
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```
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The basic implementation below provides the elements for cursor-based pagination that you'll need to do your thing in your code. Hope this helps.
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```
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from graphene import Connection, ConnectionField, Node, Int
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from graphene_django import DjangoObjectType
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from <wherever your models exist> import Place
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class Place_Node_Type(DjangoObjectType):
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class Meta:
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model = Place
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interfaces = (Node, )
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class Place_Connection(Connection):
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class Meta:
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node = Place_Node_Type
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count = Int()
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def resolve_count(root, info):
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return len(root.edges)
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class Query(object):
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places = ConnectionField(Place_Connection)
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def resolve_places(root, info, **kwargs):
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return Place.objects.all()
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```
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The following query, (the pageInfo element is included for illustration, but isn't necessary for the query to resolve):
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```
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{
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places(first: 3, after: "YXJyYXljb25uZWN0aW9uOjQx") {
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pageInfo {
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startCursor
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endCursor
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hasNextPage
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hasPreviousPage
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}
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edges {
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cursor
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node {
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id
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name
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}
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}
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}
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}
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```
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Gives us:
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```
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{
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"data": {
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"places": {
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"pageInfo": {
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"startCursor": "YXJyYXljb25uZWN0aW9uOjQy",
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"endCursor": "YXJyYXljb25uZWN0aW9uOjQ0",
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"hasNextPage": true,
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"hasPreviousPage": false
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},
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"edges": [
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{
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"cursor": "YXJyYXljb25uZWN0aW9uOjQy",
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"node": {
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"id": "UGxhY2VfTm9kZV9UeXBlOjQz",
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"name": "Wilton, Franklin, Maine, United States"
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}
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},
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{
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"cursor": "YXJyYXljb25uZWN0aW9uOjQz",
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"node": {
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"id": "UGxhY2VfTm9kZV9UeXBlOjQ0",
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"name": "Boise City, Ada, Idaho, United States"
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}
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},
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{
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"cursor": "YXJyYXljb25uZWN0aW9uOjQ0",
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"node": {
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"id": "UGxhY2VfTm9kZV9UeXBlOjQ1",
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"name": "Helena, Shelby, Akabama, USA"
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}
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}
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]
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}
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}
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}
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```
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