Add proper error handling and mesage

examples/dataset-frictionless/lib/dataset.js

@@ -5,28 +5,66 @@ import toArray from 'stream-to-array'
 
 
 export async function getDataset(directory) {
-  // get dataset descriptor and resources
-  const f11sDataset = await Dataset.load(directory)
-  const descriptor = f11sDataset.descriptor
+  try {
 
-  const resources = await Promise.all(f11sDataset.resources.map(async (resource) => {
-    let _tmp = resource.descriptor
-    let rowStream = await resource.rows({ keyed: true })
-    _tmp.sample = await toArray(rowStream)
-    _tmp.size = resource.size
-    return _tmp
-  }))
-  const readme = descriptor.readme
-  const processed = await remark()
-    .use(html)
-    .process(readme)
+    if (!directory) {
+      throw new Error('No directory provided.')
+    }
 
-  const readmeHtml = processed.toString()
-  const dataset = {
-    readme: readme,
-    readmeHtml: readmeHtml,
-    descriptor: descriptor,
-    resources: resources
+    const f11sDataset = await Dataset.load(directory)
+    const descriptor = f11sDataset.descriptor
+
+    const resources = await Promise.all(f11sDataset.resources.map(async (resource) => {
+      let _tmp = resource.descriptor
+      let rowStream = await resource.rows({ keyed: true })
+      _tmp.sample = await toArray(rowStream)
+      _tmp.size = resource.size
+      return _tmp
+    }))
+
+    const readme = descriptor.readme || ""
+
+    const processed = await remark()
+      .use(html)
+      .process(readme)
+
+    const readmeHtml = processed.toString()
+
+
+    const dataset = {
+      readme: readme,
+      readmeHtml: readmeHtml,
+      descriptor: descriptor,
+      resources: resources,
+      hasError: false,
+      errorMsg: ""
+    }
+    return dataset
+  } catch (err) {
+    console.log(err)
+    return {
+      hasError: true,
+      errorMsg: errorMessageMappings[err.message] || err.message
+    }
   }
-  return dataset
 }
+
+
+const errorMessageMappings = {
+  "No datapackage.json at destination.":
+    `
+    <div>
+      <p style="color:red;"><b>No datapackage.json file in the data directory!</b></p>
+      <p >You need to add a datapackage.json file describing your dataset to the root folder.</p>
+      <p>For more information, see <a style="color:blue;" href="https://specs.frictionlessdata.io/tabular-data-package/#example">the documentation</a></p>
+    </div>
+    `,
+  "No directory provided.":
+    `
+    <div>
+      <p style="color:red;"><b>No data directory found!</b></p>
+      <p >You need to provide a data directory with CSV data, datapackage.json, and optionally a ReadMe file.</p>
+      <p>For more information, see <a style="color:blue;" href="https://specs.frictionlessdata.io/tabular-data-package/#example">the documentation</a></p>
+    </div>
+  `,
+}