From 673ac7d3207224d750ca5962b860fa146ccbd61d Mon Sep 17 00:00:00 2001
From: pawel <pawelredzynski@gmail.com>
Date: Tue, 5 May 2020 14:20:04 +0200
Subject: [PATCH] plot: check field exists

---
 dvc/repo/plot/template.py | 20 ++++++++++++++++++++
 tests/func/test_plot.py   | 13 +++++++++++++
 2 files changed, 33 insertions(+)

diff --git a/dvc/repo/plot/template.py b/dvc/repo/plot/template.py
index 2850a6220f..f36d90a9a0 100644
--- a/dvc/repo/plot/template.py
+++ b/dvc/repo/plot/template.py
@@ -24,6 +24,13 @@ def __init__(self, template_path):
         )
 
 
+class NoFieldInDataError(DvcException):
+    def __init__(self, field_name):
+        super().__init__(
+            "Field '{}' does not exist in provided data.".format(field_name)
+        )
+
+
 class Template:
     INDENT = 4
     SEPARATORS = (",", ": ")
@@ -91,6 +98,11 @@ def fill(
         with open(template_path, "r") as fobj:
             result_content = fobj.read()
 
+        if x_field:
+            Template._check_field_exists(data, x_field)
+        if y_field:
+            Template._check_field_exists(data, y_field)
+
         result_content = Template._replace_data_anchors(
             result_content, data, priority_datafile
         )
@@ -101,6 +113,14 @@ def fill(
 
         return result_content
 
+    @staticmethod
+    def _check_field_exists(data, field):
+        for file, data_points in data.items():
+            if not any(
+                field in data_point.keys() for data_point in data_points
+            ):
+                raise NoFieldInDataError(field)
+
     @staticmethod
     def _replace_metadata_anchors(
         result_content, title, x_field, x_title, y_field, y_title
diff --git a/tests/func/test_plot.py b/tests/func/test_plot.py
index 6be11320f8..76ea8b3f6e 100644
--- a/tests/func/test_plot.py
+++ b/tests/func/test_plot.py
@@ -18,6 +18,7 @@
 from dvc.repo.plot.template import (
     TemplateNotFoundError,
     NoDataForTemplateError,
+    NoFieldInDataError,
 )
 from dvc.repo.plot import NoDataOrTemplateProvided
 
@@ -502,3 +503,15 @@ def test_plot_yaml(tmp_dir, scm, dvc):
         {"val": 2, PlotData.INDEX_FIELD: 0, "rev": "workspace"},
         {"val": 3, PlotData.INDEX_FIELD: 1, "rev": "workspace"},
     ]
+
+
+def test_raise_on_wrong_field(tmp_dir, scm, dvc):
+    metric = [{"val": 2}, {"val": 3}]
+    _write_json(tmp_dir, metric, "metric.json")
+    _run_with_metric(tmp_dir, "metric.json", "first run")
+
+    with pytest.raises(NoFieldInDataError):
+        dvc.plot("metric.json", x_field="no_val")
+
+    with pytest.raises(NoFieldInDataError):
+        dvc.plot("metric.json", y_field="no_val")