CT-2322/improve contracts error message

.changes/unreleased/Features-20230325-192830.yaml

@@ -0,0 +1,6 @@
+kind: Features
+body: Added prettier printing to ContractError class
+time: 2023-03-25T19:28:30.171461-07:00
+custom:
+  Author: kentkr
+  Issue: "7209"

core/dbt/exceptions.py

@@ -2132,14 +2132,48 @@ def __init__(self, yaml_columns, sql_columns):
 
     def get_message(self) -> str:
         msg = (
-            "Contracts are enabled for this model. "
+            "This model has an enforced contract that failed.\n"
             "Please ensure the name, data_type, and number of columns in your `yml` file "
             "match the columns in your SQL file.\n"
-            f"Schema File Columns: {self.yaml_columns}\n"
-            f"SQL File Columns: {self.sql_columns}"
+            # separate column headers by 20 spaces
+            f"{'sql col:' : <20} {'yaml col:' : <20} {'issue:' : <20}\n"
         )
-        return msg
 
+        # list of ordered matches (or not matches) for printing
+        ordered_match = []
+        # track sql cols so we don't need another for loop later
+        sql_col_set = set()
+        # for each sql col list
+        for sql_col in self.sql_columns:
+            # add sql col to set
+            sql_col_set.add(sql_col['name']) 
+            # for each yaml col list
+            for i, yaml_col in enumerate(self.yaml_columns):
+                # if name matches
+                if sql_col['name'] == yaml_col['name']:
+                    # if type matches
+                    if sql_col['formatted'] == yaml_col['formatted']:
+                        # its a perfect match!
+                        ordered_match += [[sql_col['formatted'], yaml_col['formatted'], '']]
+                        break
+                    else:
+                        # same name, diff type
+                        ordered_match += [[sql_col['formatted'], yaml_col['formatted'], 'Incorrect type']]
+                        break
+                # if last loop, then no name match
+                if i == len(self.yaml_columns)-1:
+                    ordered_match += [[sql_col['formatted'], '', 'No match']]
+
+        # now add all yaml cols without a match
+        for yaml_col in self.yaml_columns:
+            if yaml_col['name'] not in sql_col_set:
+                ordered_match += [['', yaml_col['name'], 'No match']]
+
+        # add each match to the message, printed in columns
+        for match in ordered_match:
+            msg += f'{match[0] : <20} {match[1] : <20} {match[2] : <20}\n'
+
+        return msg
 
 # not modifying these since rpc should be deprecated soon
 class UnknownAsyncIDException(Exception):

core/dbt/include/global_project/macros/materializations/models/table/columns_spec_ddl.sql

@@ -43,7 +43,7 @@
   {%- set string_yaml_columns = stringify_formatted_columns(yaml_columns) -%}
 
   {%- if sql_columns|length != yaml_columns|length -%}
-    {%- do exceptions.raise_contract_error(string_yaml_columns, string_sql_columns) -%}
+    {%- do exceptions.raise_contract_error(yaml_columns, sql_columns) -%}
   {%- endif -%}
 
   {%- for sql_col in sql_columns -%}
@@ -56,11 +56,11 @@
     {%- endfor -%}
     {%- if not yaml_col -%}
       {#-- Column with name not found in yaml #}
-      {%- do exceptions.raise_contract_error(string_yaml_columns, string_sql_columns) -%}
+      {%- do exceptions.raise_contract_error(yaml_columns, sql_columns) -%}
     {%- endif -%}
     {%- if sql_col['formatted'] != yaml_col[0]['formatted'] -%}
       {#-- Column data types don't match #}
-      {%- do exceptions.raise_contract_error(string_yaml_columns, string_sql_columns) -%}
+      {%- do exceptions.raise_contract_error(yaml_columns, sql_columns) -%}
     {%- endif -%}
   {%- endfor -%}