feat: add json resolver (#400)

The json codec is included in the multiformats module so no extra
deps are needed.

Similar to #397

Author: achingbrain

packages/ipfs-unixfs-exporter/src/resolvers/dag-cbor.ts

@@ -1,67 +1,12 @@
 import * as dagCbor from '@ipld/dag-cbor'
-import errCode from 'err-code'
-import { CID } from 'multiformats/cid'
+import { resolveObjectPath } from '../utils/resolve-object-path.js'
 import type { Resolver } from '../index.js'
 
 const resolve: Resolver = async (cid, name, path, toResolve, resolve, depth, blockstore, options) => {
   const block = await blockstore.get(cid, options)
   const object = dagCbor.decode<any>(block)
-  let subObject = object
-  let subPath = path
 
-  while (toResolve.length > 0) {
-    const prop = toResolve[0]
-
-    if (prop in subObject) {
-      // remove the bit of the path we have resolved
-      toResolve.shift()
-      subPath = `${subPath}/${prop}`
-
-      const subObjectCid = CID.asCID(subObject[prop])
-      if (subObjectCid != null) {
-        return {
-          entry: {
-            type: 'object',
-            name,
-            path,
-            cid,
-            node: block,
-            depth,
-            size: BigInt(block.length),
-            content: async function * () {
-              yield object
-            }
-          },
-          next: {
-            cid: subObjectCid,
-            name: prop,
-            path: subPath,
-            toResolve
-          }
-        }
-      }
-
-      subObject = subObject[prop]
-    } else {
-      // cannot resolve further
-      throw errCode(new Error(`No property named ${prop} found in cbor node ${cid}`), 'ERR_NO_PROP')
-    }
-  }
-
-  return {
-    entry: {
-      type: 'object',
-      name,
-      path,
-      cid,
-      node: block,
-      depth,
-      size: BigInt(block.length),
-      content: async function * () {
-        yield object
-      }
-    }
-  }
+  return resolveObjectPath(object, block, cid, name, path, toResolve, depth)
 }
 
 export default resolve

packages/ipfs-unixfs-exporter/src/resolvers/dag-json.ts

@@ -1,67 +1,12 @@
 import * as dagJson from '@ipld/dag-json'
-import errCode from 'err-code'
-import { CID } from 'multiformats/cid'
+import { resolveObjectPath } from '../utils/resolve-object-path.js'
 import type { Resolver } from '../index.js'
 
 const resolve: Resolver = async (cid, name, path, toResolve, resolve, depth, blockstore, options) => {
   const block = await blockstore.get(cid, options)
   const object = dagJson.decode<any>(block)
-  let subObject = object
-  let subPath = path
 
-  while (toResolve.length > 0) {
-    const prop = toResolve[0]
-
-    if (prop in subObject) {
-      // remove the bit of the path we have resolved
-      toResolve.shift()
-      subPath = `${subPath}/${prop}`
-
-      const subObjectCid = CID.asCID(subObject[prop])
-      if (subObjectCid != null) {
-        return {
-          entry: {
-            type: 'object',
-            name,
-            path,
-            cid,
-            node: block,
-            depth,
-            size: BigInt(block.length),
-            content: async function * () {
-              yield object
-            }
-          },
-          next: {
-            cid: subObjectCid,
-            name: prop,
-            path: subPath,
-            toResolve
-          }
-        }
-      }
-
-      subObject = subObject[prop]
-    } else {
-      // cannot resolve further
-      throw errCode(new Error(`No property named ${prop} found in dag-json node ${cid}`), 'ERR_NO_PROP')
-    }
-  }
-
-  return {
-    entry: {
-      type: 'object',
-      name,
-      path,
-      cid,
-      node: block,
-      depth,
-      size: BigInt(block.length),
-      content: async function * () {
-        yield object
-      }
-    }
-  }
+  return resolveObjectPath(object, block, cid, name, path, toResolve, depth)
 }
 
 export default resolve

packages/ipfs-unixfs-exporter/src/resolvers/index.ts

@@ -2,11 +2,13 @@ import * as dagCbor from '@ipld/dag-cbor'
 import * as dagJson from '@ipld/dag-json'
 import * as dagPb from '@ipld/dag-pb'
 import errCode from 'err-code'
+import * as json from 'multiformats/codecs/json'
 import * as raw from 'multiformats/codecs/raw'
 import { identity } from 'multiformats/hashes/identity'
 import dagCborResolver from './dag-cbor.js'
 import dagJsonResolver from './dag-json.js'
 import identifyResolver from './identity.js'
+import jsonResolver from './json.js'
 import rawResolver from './raw.js'
 import dagPbResolver from './unixfs-v1/index.js'
 import type { Resolve, Resolver } from '../index.js'
@@ -16,7 +18,8 @@ const resolvers: Record<number, Resolver> = {
   [raw.code]: rawResolver,
   [dagCbor.code]: dagCborResolver,
   [dagJson.code]: dagJsonResolver,
-  [identity.code]: identifyResolver
+  [identity.code]: identifyResolver,
+  [json.code]: jsonResolver
 }
 
 const resolve: Resolve = async (cid, name, path, toResolve, depth, blockstore, options) => {

packages/ipfs-unixfs-exporter/src/resolvers/json.ts

@@ -0,0 +1,12 @@
+import * as json from 'multiformats/codecs/json'
+import { resolveObjectPath } from '../utils/resolve-object-path.js'
+import type { Resolver } from '../index.js'
+
+const resolve: Resolver = async (cid, name, path, toResolve, resolve, depth, blockstore, options) => {
+  const block = await blockstore.get(cid, options)
+  const object = json.decode<any>(block)
+
+  return resolveObjectPath(object, block, cid, name, path, toResolve, depth)
+}
+
+export default resolve

packages/ipfs-unixfs-exporter/src/utils/resolve-object-path.ts

@@ -0,0 +1,62 @@
+import errCode from 'err-code'
+import { CID } from 'multiformats/cid'
+import type { ResolveResult } from '../index.js'
+
+export function resolveObjectPath (object: any, block: Uint8Array, cid: CID, name: string, path: string, toResolve: string[], depth: number): ResolveResult {
+  let subObject = object
+  let subPath = path
+
+  while (toResolve.length > 0) {
+    const prop = toResolve[0]
+
+    if (prop in subObject) {
+      // remove the bit of the path we have resolved
+      toResolve.shift()
+      subPath = `${subPath}/${prop}`
+
+      const subObjectCid = CID.asCID(subObject[prop])
+      if (subObjectCid != null) {
+        return {
+          entry: {
+            type: 'object',
+            name,
+            path,
+            cid,
+            node: block,
+            depth,
+            size: BigInt(block.length),
+            content: async function * () {
+              yield object
+            }
+          },
+          next: {
+            cid: subObjectCid,
+            name: prop,
+            path: subPath,
+            toResolve
+          }
+        }
+      }
+
+      subObject = subObject[prop]
+    } else {
+      // cannot resolve further
+      throw errCode(new Error(`No property named ${prop} found in node ${cid}`), 'ERR_NO_PROP')
+    }
+  }
+
+  return {
+    entry: {
+      type: 'object',
+      name,
+      path,
+      cid,
+      node: block,
+      depth,
+      size: BigInt(block.length),
+      content: async function * () {
+        yield object
+      }
+    }
+  }
+}

packages/ipfs-unixfs-exporter/test/exporter.spec.ts

@@ -17,6 +17,7 @@ import first from 'it-first'
 import last from 'it-last'
 import toBuffer from 'it-to-buffer'
 import { CID } from 'multiformats/cid'
+import * as json from 'multiformats/codecs/json'
 import * as raw from 'multiformats/codecs/raw'
 import { identity } from 'multiformats/hashes/identity'
 import { sha256 } from 'multiformats/hashes/sha2'
@@ -978,7 +979,7 @@ describe('exporter', () => {
     expect(data).to.deep.equal(smallFile)
   })
 
-  it('errors when exporting a non-existent key from a cbor node', async () => {
+  it('errors when exporting a non-existent key from a dag-cbor node', async () => {
     const node = {
       foo: 'bar'
     }
@@ -994,7 +995,7 @@ describe('exporter', () => {
     }
   })
 
-  it('exports a cbor node', async () => {
+  it('exports a dag-cbor node', async () => {
     const node = {
       foo: 'bar'
     }
@@ -1011,7 +1012,7 @@ describe('exporter', () => {
     return expect(first(exported.content())).to.eventually.deep.equal(node)
   })
 
-  it('errors when exporting a non-existent key from a json node', async () => {
+  it('errors when exporting a non-existent key from a dag-json node', async () => {
     const node = {
       foo: 'bar'
     }
@@ -1027,7 +1028,7 @@ describe('exporter', () => {
     }
   })
 
-  it('exports a json node', async () => {
+  it('exports a dag-json node', async () => {
     const node = {
       foo: 'bar'
     }
@@ -1044,6 +1045,39 @@ describe('exporter', () => {
     return expect(first(exported.content())).to.eventually.deep.equal(node)
   })
 
+  it('errors when exporting a non-existent key from a json node', async () => {
+    const node = {
+      foo: 'bar'
+    }
+
+    const jsonBlock = json.encode(node)
+    const cid = CID.createV1(json.code, await sha256.digest(jsonBlock))
+    await block.put(cid, jsonBlock)
+
+    try {
+      await exporter(`${cid}/baz`, block)
+    } catch (err: any) {
+      expect(err.code).to.equal('ERR_NO_PROP')
+    }
+  })
+
+  it('exports a json node', async () => {
+    const node = {
+      foo: 'bar'
+    }
+
+    const jsonBlock = json.encode(node)
+    const cid = CID.createV1(json.code, await sha256.digest(jsonBlock))
+    await block.put(cid, jsonBlock)
+    const exported = await exporter(`${cid}`, block)
+
+    if (exported.type !== 'object') {
+      throw new Error('Unexpected type')
+    }
+
+    return expect(first(exported.content())).to.eventually.deep.equal(node)
+  })
+
   it('errors when exporting a node with no resolver', async () => {
     const cid = CID.create(1, 0x78, CID.parse('zdj7WkRPAX9o9nb9zPbXzwG7JEs78uyhwbUs8JSUayB98DWWY').multihash)