Merge pull request #1 from tjenkinson/smaller-cursor

Restructure cursor to make it smaller

Author: tjenkinson

README.md

@@ -117,7 +117,7 @@ E.g.
 {
   "edges": [
     {
-      "cursor": "SuWlzjWxdtSVDzgPp_mVdQH7S4pbbIpNqmJJFWwXOws.9732ntsWW_36ePfEiU1_85i4VHGpnlt60LcekRaV6hZiIfLaDEJyTxv4_mT0gVYjC05he25PbktssRXIQMdfnwfl2PkS47CW75s-XwbfYuhuaZJZfUpZLW5O7xVWf5R2YD7FEdd53lDlXJDbEE5TvRvM8TNkhCSh8LTnJEFNqADHkbWz-H7pDPOaOBsLE3n_EUYcf498pgjPJCRN",
+      "cursor": "l1X624m67Z5aYShVOLrThEcP7c-ezmCc4C48Dvxtt98.x7zYjxX9VEWDA1KAnJii8zyw5DP_OdIRnSkXATGhwTy6Wf0SSkjdjq6pTl9qxhp87EI-85pUJW9Thz_A6F_8BzlgccgDV-hXWjEj3CsGl96tSaA-X0_qNWBu425Mt6t5j3wNSdk8sSArBQ",
       "node": {
         "id": 1,
         "first_name": "Joe",

src/__snapshots__/sql-cursor-pagination.test.ts.snap

@@ -6,7 +6,6 @@ import { MaybePromise } from './maybe-promise';
 import { Cursor } from './zod-models/cursor';
 import { FieldValue } from './zod-models/field-value';
 import { FieldWithOrder } from './zod-models/field-with-order';
-import { FieldWithValue } from './zod-models/field-with-value';
 
 const ivCipherTextRegex = /^([^.]+)\.([^.]+)$/;
 
@@ -149,14 +148,14 @@ export function buildCursor<TNode extends Record<string, unknown>>({
   node: TNode;
   sortFields: readonly FieldWithOrder[];
 }): Cursor {
-  const fields: FieldWithValue[] = [];
+  const fields: Cursor['fields'] = {};
 
   for (const { field } of sortFields) {
     const { alias } = parseFieldName(field);
     if (!(alias in node)) {
       throw new ErrUnexpected(`"${alias}" field is missing`);
     }
-    fields.push({ field: alias, value: FieldValue.parse(node[alias]) });
+    fields[alias] = FieldValue.parse(node[alias]);
   }
 
   return { fields, queryName };

src/arrays.ts

@@ -0,0 +1,5 @@
+export function areSetsEqual<T>(a: ReadonlySet<T>, b: ReadonlySet<T>): boolean {
+  if (a.size !== b.size) return false;
+  for (const _a of a) if (!b.has(_a)) return false;
+  return true;
+}

src/cursor.ts

@@ -623,7 +623,11 @@ describe('SqlCursorPagination', () => {
             query: {
               beforeCursor: all.edges[0].cursor,
               last: 1,
-              sortFields: [{ field: 'email', order: Asc }],
+              sortFields: [
+                { field: 'email', order: Asc },
+                { field: 'last_name', order: Asc },
+                { field: 'id', order: Asc },
+              ],
             },
           }),
       ).rejects.toThrowError(ErrBeforeCursorWrongSortConfig);

src/set.ts

@@ -1,5 +1,4 @@
 import pMap from 'p-map';
-import { areArraysEqual } from './arrays';
 import { notNull } from './assert';
 import { RawCursor, buildCursor, encryptCursor, resolveCursor } from './cursor';
 import { CursorSecret } from './cursor-secret';
@@ -22,6 +21,7 @@ import {
 import { parseFieldName } from './field-name';
 import { MaybePromise } from './maybe-promise';
 import { FragmentBuilder, QueryBuilder } from './query-builder';
+import { areSetsEqual } from './set';
 import { Cursor } from './zod-models/cursor';
 import { FieldWithOrder } from './zod-models/field-with-order';
 import { GenericQueryResult } from './zod-models/generic-query-result';
@@ -309,9 +309,9 @@ export async function withPagination<
 
     // fields in the cursor must match the ones being requested
     if (
-      !areArraysEqual(
-        sortFields.map(({ field }) => parseFieldName(field).name),
-        cursor.fields.map(({ field }) => field),
+      !areSetsEqual(
+        new Set(sortFields.map(({ field }) => parseFieldName(field).name)),
+        new Set(Object.keys(cursor.fields)),
       )
     ) {
       if (type === 'before') {
@@ -331,7 +331,8 @@ export async function withPagination<
         whereQuery.appendText(`(`);
         for (let j = 0; j <= i; j++) {
           const { field, order } = sortFields[j];
-          const { value } = c.fields[j];
+          const fieldName = parseFieldName(field).name;
+          const value = c.fields[fieldName];
           const sign =
             i === j
               ? maybeFlip(order, type === 'before') === Asc
@@ -341,7 +342,7 @@ export async function withPagination<
 
           if (j > 0) whereQuery.appendText(` AND `);
           whereQuery
-            .appendText(`${quoteField(parseFieldName(field).name)}${sign}`)
+            .appendText(`${quoteField(fieldName)}${sign}`)
             .appendValue(value);
         }
         whereQuery.appendText(`)`);

src/sql-cursor-pagination.test.ts

@@ -1,10 +1,11 @@
 import { z } from 'zod';
-import { FieldWithValue } from './field-with-value';
+import { FieldName } from './field-name';
+import { FieldValue } from './field-value';
 import { QueryName } from './query-name';
 
 export const Cursor = z
   .object({
-    fields: z.array(FieldWithValue).min(1),
+    fields: z.record(FieldName, FieldValue),
     queryName: QueryName,
   })
   .strict()