feat(gatsby): Add details to pagination info (#13625)

packages/gatsby/src/schema/__tests__/pagination.js

@@ -0,0 +1,103 @@
+const { paginate } = require(`../resolvers`)
+
+describe(`Paginate query results`, () => {
+  const results = [{ id: 1 }, { id: 2 }, { id: 3 }, { id: 4 }]
+
+  it(`returns results`, async () => {
+    const args = { limit: 1 }
+    const nodes = paginate(results, args).edges.map(({ node }) => node)
+    expect(nodes).toEqual([results[0]])
+  })
+
+  it(`returns next and previos nodes`, async () => {
+    const args = { limit: 3 }
+    const next = paginate(results, args).edges.map(({ next }) => next)
+    const prev = paginate(results, args).edges.map(({ previous }) => previous)
+    expect(next).toEqual([results[1], results[2], undefined])
+    expect(prev).toEqual([undefined, results[0], results[1]])
+  })
+
+  it(`returns correct pagination info with limit only`, async () => {
+    const args = { limit: 2 }
+    const { pageInfo, totalCount } = paginate(results, args)
+    expect(totalCount).toBe(4)
+    expect(pageInfo).toEqual({
+      currentPage: 1,
+      hasNextPage: true,
+      hasPreviousPage: false,
+      itemCount: 2,
+      pageCount: 2,
+      perPage: 2,
+    })
+  })
+
+  it(`returns correct pagination info with skip and limit`, async () => {
+    const args = { skip: 1, limit: 2 }
+    const { pageInfo, totalCount } = paginate(results, args)
+    expect(totalCount).toBe(4)
+    expect(pageInfo).toEqual({
+      currentPage: 2,
+      hasNextPage: true,
+      hasPreviousPage: true,
+      itemCount: 2,
+      pageCount: 3,
+      perPage: 2,
+    })
+  })
+
+  it(`returns correct pagination info with skip and limit`, async () => {
+    const args = { skip: 2, limit: 2 }
+    const { pageInfo, totalCount } = paginate(results, args)
+    expect(totalCount).toBe(4)
+    expect(pageInfo).toEqual({
+      currentPage: 2,
+      hasNextPage: false,
+      hasPreviousPage: true,
+      itemCount: 2,
+      pageCount: 2,
+      perPage: 2,
+    })
+  })
+
+  it(`returns correct pagination info with skip only`, async () => {
+    const args = { skip: 1 }
+    const { pageInfo, totalCount } = paginate(results, args)
+    expect(totalCount).toBe(4)
+    expect(pageInfo).toEqual({
+      currentPage: 2,
+      hasNextPage: false,
+      hasPreviousPage: true,
+      itemCount: 3,
+      pageCount: 2,
+      perPage: undefined,
+    })
+  })
+
+  it(`returns correct pagination info with skip > totalCount`, async () => {
+    const args = { skip: 10 }
+    const { pageInfo, totalCount } = paginate(results, args)
+    expect(totalCount).toBe(4)
+    expect(pageInfo).toEqual({
+      currentPage: 2,
+      hasNextPage: false,
+      hasPreviousPage: true,
+      itemCount: 0,
+      pageCount: 2,
+      perPage: undefined,
+    })
+  })
+
+  it(`returns correct pagination info with limit > totalCount`, async () => {
+    const args = { limit: 10 }
+    const { pageInfo, totalCount } = paginate(results, args)
+    expect(totalCount).toBe(4)
+    expect(pageInfo).toEqual({
+      currentPage: 1,
+      hasNextPage: false,
+      hasPreviousPage: false,
+      itemCount: 4,
+      pageCount: 1,
+      perPage: 10,
+    })
+  })
+})

packages/gatsby/src/schema/resolvers.js

@@ -75,6 +75,13 @@ const paginate = (results = [], { skip = 0, limit }) => {
   const count = results.length
   const items = results.slice(skip, limit && skip + limit)
 
+  const pageCount = limit
+    ? Math.ceil(skip / limit) + Math.ceil((count - skip) / limit)
+    : skip
+    ? 2
+    : 1
+  const currentPage = limit ? Math.ceil(skip / limit) + 1 : skip ? 2 : 1
+  const hasPreviousPage = currentPage > 1
   const hasNextPage = skip + limit < count
 
   return {
@@ -88,7 +95,12 @@ const paginate = (results = [], { skip = 0, limit }) => {
     }),
     nodes: items,
     pageInfo: {
+      currentPage,
+      hasPreviousPage,
       hasNextPage,
+      itemCount: items.length,
+      pageCount,
+      perPage: limit,
     },
   }
 }
@@ -188,4 +200,5 @@ module.exports = {
   link,
   distinct,
   group,
+  paginate,
 }

packages/gatsby/src/schema/types/pagination.js

@@ -4,12 +4,12 @@ const { distinct, group } = require(`../resolvers`)
 const getPageInfo = ({ schemaComposer }) =>
   schemaComposer.getOrCreateOTC(`PageInfo`, tc => {
     tc.addFields({
+      currentPage: `Int!`,
+      hasPreviousPage: `Boolean!`,
       hasNextPage: `Boolean!`,
-      // currentPage: `Int!`,
-      // hasPreviousPage: `Boolean!`,
-      // itemCount: `Int!`,
-      // pageCount: `Int!`,
-      // perPage: `Int`,
+      itemCount: `Int!`,
+      pageCount: `Int!`,
+      perPage: `Int`,
     })
   })