feat(cli): improve UX of multi-item selection

When asking the user to select 1 or more items, e.g. models to import,
require at least one item to be selected.

This prevents users from accidentally pressing ENTER instead of SPACE
to select an item from the list, in which case the prompt is resolved
with an empty list and thus the CLI command ends prematurely.

Signed-off-by: Miroslav Bajtoš <mbajtoss@gmail.com>

packages/cli/generators/discover/index.js

@@ -161,6 +161,10 @@ module.exports = class DiscoveryGenerator extends ArtifactGenerator {
         when:
           this.discoveringModels === undefined &&
           !this.artifactInfo.modelDefinitions,
+        // Require at least one model to be selected
+        // This prevents users from accidentally pressing ENTER instead of SPACE
+        // to select a model from the list
+        validate: result => !!result.length,
       },
     ];
 

packages/cli/generators/import-lb3-models/index.js

@@ -80,6 +80,9 @@ Learn more at https://loopback.io/doc/en/lb4/Importing-LB3-models.html
         message: 'Select models to import:',
         type: 'checkbox',
         choices: modelNames,
+        // Require at least one model to be selected
+        // This prevents users from accidentally pressing ENTER instead of SPACE
+        // to select a model from the list
         validate: result => !!result.length,
         // TODO: add a CLI flag to supply these names programmatically
       },

packages/cli/generators/openapi/index.js

@@ -102,6 +102,10 @@ module.exports = class OpenApiGenerator extends BaseGenerator {
         message: 'Select controllers to be generated:',
         type: 'checkbox',
         choices: choices,
+        // Require at least one item to be selected
+        // This prevents users from accidentally pressing ENTER instead of SPACE
+        // to select an item from the list
+        validate: result => !!result.length,
       },
     ];
     const selections =

packages/cli/generators/repository/index.js

@@ -354,6 +354,10 @@ module.exports = class RepositoryGenerator extends ArtifactGenerator {
         message: PROMPT_MESSAGE_MODEL,
         choices: modelList,
         when: this.artifactInfo.modelNameList === undefined,
+        // Require at least one model to be selected
+        // This prevents users from accidentally pressing ENTER instead of SPACE
+        // to select a model from the list
+        validate: result => !!result.length,
       },
     ])
       .then(props => {