Move responsibility of serialization to the adapters

src/config.js

@@ -28,17 +28,17 @@ exports.getConfig = async () => {
     if (!_config.storeState) {
       const statePath = path.join(configDir, 'exodus.state.json')
       _config.storeState = async (state) => {
-        return fs.writeFile(statePath, state, 'utf8')
+        return fs.writeFile(statePath, JSON.stringify(state, null, 2), 'utf8')
       }
     }
     if (!_config.fetchState) {
       _config.fetchState = async () => {
         const statePath = path.join(configDir, 'exodus.state.json')
         try {
-          return await fs.readFile(statePath, 'utf8')
+          return JSON.parse(await fs.readFile(statePath, 'utf8'))
         } catch (err) {
           if (err.code !== 'ENOENT') throw err
-          return '{}'
+          return {}
         }
       }
     }
@@ -50,9 +50,8 @@ const defaultConfig = {
   // The folder to store migration scripts in.
   migrationsDirectory: './migrations',
 
-  // Persists the current migration state. The `state`
-  // argument will always be a JSON-serialized object.
-  // Store it to redis, disk, database, ... whatever suits you.
+  // Persists the current migration state. The `state` argument
+  // will always be an object. Store it as JSON to redis, disk, etc.
   // OPTIONAL: If undefined, Exodus falls back to exodus.state.json
   // storeState: async (state, context) => {},
 

src/index.js

@@ -45,7 +45,7 @@ exports.run = async () => {
   const files = await listDirectoryFiles(config.migrationsDirectory)
 
   // figure out which ones havent already been ran
-  const state = JSON.parse(await config.fetchState(context))
+  const state = await config.fetchState(context)
   state.history = state.history || []
 
   // create an ID for our round so we can undo latest batch later
@@ -87,7 +87,7 @@ exports.run = async () => {
   state.history.forEach((job) => {
     delete job.path
   })
-  await config.storeState(JSON.stringify(state), context)
+  await config.storeState(state, context)
   return { state, ranMigrations: pendingMigrations }
 }
 

src/templates/config.js

@@ -2,9 +2,8 @@ module.exports = exports = {
   // The folder to store migration scripts in.
   // migrationsDirectory: './migrations',
 
-  // Persists the current migration state. The `state`
-  // argument will always be a JSON-serialized object.
-  // Store it to redis, disk, database, ... whatever suits you.
+  // Persists the current migration state. The `state` argument
+  // will always be an object. Store it as JSON to redis, disk, etc.
   // OPTIONAL: If undefined, Exodus falls back to exodus.state.json
   // storeState: async (state, context) => {},