Throw on unsupported format.

src/formats/formats.js

@@ -3,12 +3,20 @@ import tomlFormatter from './toml';
 import jsonFormatter from './json';
 import FrontmatterFormatter from './frontmatter';
 
+export const supportedFormats = [
+  'yml',
+  'yaml',
+  'toml',
+  'json',
+  'frontmatter',
+];
+
 export const formatToExtension = format => ({
-  markdown: 'md',
+  yml: 'yml',
   yaml: 'yml',
   toml: 'toml',
   json: 'json',
-  html: 'html',
+  frontmatter: 'md',
 }[format]);
 
 export function formatByExtension(extension) {
@@ -20,7 +28,7 @@ export function formatByExtension(extension) {
     md: FrontmatterFormatter,
     markdown: FrontmatterFormatter,
     html: FrontmatterFormatter,
-  }[extension] || FrontmatterFormatter;
+  }[extension];
 }
 
 function formatByName(name) {
@@ -30,7 +38,7 @@ function formatByName(name) {
     toml: tomlFormatter,
     json: jsonFormatter,
     frontmatter: FrontmatterFormatter,
-  }[name] || FrontmatterFormatter;
+  }[name];
 }
 
 export function resolveFormat(collectionOrEntity, entry) {
@@ -55,5 +63,5 @@ export function resolveFormat(collectionOrEntity, entry) {
   }
 
   // If no format is specified and it cannot be inferred, return the default.
-  return formatByName();
+  return formatByName('frontmatter');
 }

src/reducers/collections.js

@@ -1,23 +1,22 @@
 import { OrderedMap, fromJS } from 'immutable';
-import { has } from 'lodash';
+import { has, get } from 'lodash';
 import consoleError from '../lib/consoleError';
 import { CONFIG_SUCCESS } from '../actions/config';
 import { FILES, FOLDER } from '../constants/collectionTypes';
 import { INFERABLE_FIELDS } from '../constants/fieldInference';
-import { formatToExtension } from '../formats/formats';
+import { formatByExtension, formatToExtension, supportedFormats } from '../formats/formats';
 
 const collections = (state = null, action) => {
   const configCollections = action.payload && action.payload.collections;
   switch (action.type) {
     case CONFIG_SUCCESS:
       return OrderedMap().withMutations((map) => {
         (configCollections || []).forEach((configCollection) => {
+          validateCollection(configCollection);
           if (has(configCollection, 'folder')) {
             configCollection.type = FOLDER; // eslint-disable-line no-param-reassign
           } else if (has(configCollection, 'files')) {
             configCollection.type = FILES; // eslint-disable-line no-param-reassign
-          } else {
-            throw new Error('Unknown collection type. Collections can be either Folder based or File based. Please verify your site configuration');
           }
           map.set(configCollection.name, fromJS(configCollection));
         });
@@ -27,10 +26,24 @@ const collections = (state = null, action) => {
   }
 };
 
+function validateCollection(configCollection) {
+  const collectionName = get(configCollection, 'name');
+  if (!has(configCollection, 'folder') && !has(configCollection, 'files')) {
+    throw new Error(`Unknown collection type for collection "${ collectionName }". Collections can be either Folder based or File based.`);
+  }
+  if (has(configCollection, 'format') && !supportedFormats.includes(get(configCollection, 'format'))) {
+    throw new Error(`Unknown collection format for collection "${ collectionName }". Supported formats are ${ supportedFormats.join(',') }`);
+  }
+  if (!has(configCollection, 'format') && has(configCollection, 'extension') && !formatByExtension(get(configCollection, 'extension'))) {
+    // Cannot infer format from extension.
+    throw new Error(`Please set a format for collection "${ collectionName }". Supported formats are ${ supportedFormats.join(',') }`);
+  }
+}
+
 const selectors = {
   [FOLDER]: {
     entryExtension(collection) {
-      return collection.get('extension') || formatToExtension(collection.get('format') || 'markdown');
+      return collection.get('extension') || formatToExtension(collection.get('format') || 'frontmatter');
     },
     fields(collection) {
       return collection.get('fields');