Add preview to datasets as specified in the Kedro catalog under metadata

RELEASE.md

@@ -15,7 +15,8 @@ Please follow the established format:
 
 ## Major features and improvements
 
-- Add support for new kedro-viz layer configuration in kedro-datasets. (#1373)
+- Add support for new kedro-viz layer configuration in kedro-datasets version 1.3.0 or more. 
+- Add support for new kedro-viz preview_args configuration in kedro-datasets version 1.3.0 or more. 
 
 # Release 6.2.0
 

demo-project/conf/base/catalog_01_raw.yml

@@ -1,21 +1,29 @@
 companies:
   type: pandas.CSVDataSet
   filepath: ${base_location}/01_raw/companies.csv
-  layer: raw
+  metadata:
+    kedro-viz:
+      layer: raw
+      preview_args:
+        nrows: 5
 
 reviews:
   type: pandas.CSVDataSet
   filepath: ${base_location}/01_raw/reviews.csv
   metadata:
     kedro-viz:
+      layer: raw
       preview_args: 
-        nrows: 4
+        nrows: 10
+
 
 shuttles:
   type: pandas.ExcelDataSet
   filepath: ${base_location}/01_raw/shuttles.xlsx
   metadata:
     kedro-viz:
       layer: raw
+      preview_args:
+        nrows: 15 
 
 

package/kedro_viz/models/flowchart.py

@@ -449,6 +449,8 @@ class DataNode(GraphNode):
     # the list of modular pipelines this data node belongs to
     modular_pipelines: List[str] = field(init=False)
 
+    viz_metadata: Optional[Dict] = field(init=False)
+
     # command to run the pipeline to this node
     run_command: Optional[str] = field(init=False, default=None)
 
@@ -465,6 +467,12 @@ def __post_init__(self):
         self.modular_pipelines = self._expand_namespaces(
             self._get_namespace(self.full_name)
         )
+        metadata = getattr(self.kedro_obj, "metadata", None)
+        if metadata:
+            try:
+                self.viz_metadata = metadata["kedro-viz"]
+            except (AttributeError, KeyError):  # pragma: no cover
+                logger.debug("Kedro-viz metadata not found for %s", self.full_name)
 
     # TODO: improve this scheme.
     def is_plot_node(self):
@@ -495,7 +503,15 @@ def is_tracking_node(self):
 
     def is_preview_node(self):
         """Checks if the current node has a preview"""
-        return hasattr(self.kedro_obj, "_preview")
+        try:
+            is_preview = bool(self.viz_metadata["preview_args"])
+        except (AttributeError, KeyError):
+            return False
+        return is_preview
+
+    def get_preview_args(self):
+        """Gets the preview arguments for a dataset"""
+        return self.viz_metadata["preview_args"]
 
 
 @dataclass
@@ -602,7 +618,7 @@ def __post_init__(self, data_node: DataNode):
             self.tracking_data = dataset.load()
         elif data_node.is_preview_node():
             try:
-                self.preview = dataset._preview()  # type: ignore
+                self.preview = dataset._preview(**data_node.get_preview_args())  # type: ignore
             except Exception as exc:  # pylint: disable=broad-except # pragma: no cover
                 logger.warning(
                     "'%s' could not be previewed. Full exception: %s: %s",

package/tests/test_models/test_flowchart.py

@@ -1,3 +1,4 @@
+# pylint: disable=too-many-public-methods
 import base64
 from functools import partial
 from pathlib import Path
@@ -368,6 +369,29 @@ def test_data_node_metadata(self):
         assert data_node_metadata.filepath == "/tmp/dataset.csv"
         assert data_node_metadata.run_command == "kedro run --to-outputs=dataset"
 
+    def test_preview_args_not_exist(self):
+        metadata = {"kedro-viz": {"something": 3}}
+        dataset = CSVDataSet(filepath="test.csv", metadata=metadata)
+        data_node = GraphNode.create_data_node(
+            full_name="dataset",
+            tags=set(),
+            layer=None,
+            dataset=dataset,
+        )
+        assert not data_node.is_preview_node()
+
+    def test_get_preview_args(self):
+        metadata = {"kedro-viz": {"preview_args": {"nrows": 3}}}
+        dataset = CSVDataSet(filepath="test.csv", metadata=metadata)
+        data_node = GraphNode.create_data_node(
+            full_name="dataset",
+            tags=set(),
+            layer=None,
+            dataset=dataset,
+        )
+        assert data_node.is_preview_node()
+        assert data_node.get_preview_args() == {"nrows": 3}
+
     def test_preview_data_node_metadata(self):
         mock_preview_data = {
             "columns": ["id", "company_rating", "company_location"],

src/components/metadata-modal/metadata-modal.js

@@ -46,7 +46,7 @@ const MetadataModal = ({ metadata, onToggle, visible }) => {
         </div>
         {hasPreview && (
           <div className="pipeline-metadata-modal__preview-text">
-            Previewing first 40 rows only
+            Previewing first {metadata.preview.data.length} rows
           </div>
         )}
       </div>

src/components/metadata/metadata.js

@@ -29,7 +29,6 @@ import './styles/metadata.css';
  * Shows node meta data
  */
 const MetaData = ({
-  flags,
   isPrettyNameOn,
   metadata,
   onToggleCode,
@@ -58,7 +57,7 @@ const MetaData = ({
   const hasPlot = Boolean(metadata?.plot);
   const hasImage = Boolean(metadata?.image);
   const hasTrackingData = Boolean(metadata?.trackingData);
-  const hasPreviewData = Boolean(metadata?.preview) && flags.previewDataSet;
+  const hasPreviewData = Boolean(metadata?.preview);
   const isMetricsTrackingDataset = nodeTypeIcon === 'metricsTracking';
   const hasCode = Boolean(metadata?.code);
   const isTranscoded = Boolean(metadata?.originalType);
@@ -326,7 +325,6 @@ const MetaData = ({
 };
 
 export const mapStateToProps = (state, ownProps) => ({
-  flags: state.flags,
   isPrettyNameOn: state.prettyName,
   metadata: getClickedNodeMetaData(state),
   theme: state.theme,

src/config.js

@@ -63,12 +63,6 @@ export const flags = {
     default: false,
     icon: '🔛',
   },
-  previewDataSet: {
-    name: 'Preview datasets',
-    description: 'Enable dataset previews in the metadata panel',
-    default: true,
-    icon: '🗂',
-  },
 };
 
 export const settings = {