Return errors applying filters as Render errors

osteele · Jul 21, 2017 · 8ee8cef · 8ee8cef
1 parent de5fffa
commit 8ee8cef
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Showing 3 changed files with 16 additions and 1 deletion.
diff --git a/expressions/builders.go b/expressions/builders.go
@@ -22,7 +22,10 @@ func makeFilter(fn valueFn, name string, args []valueFn) valueFn {
 	return func(ctx Context) evaluator.Value {
 		result, err := ctx.ApplyFilter(name, fn, args)
 		if err != nil {
-			panic(err)
+			panic(FilterError{
+				FilterName: name,
+				Err:        err,
+			})
 		}
 		return evaluator.ValueOf(result)
 	}

diff --git a/expressions/expressions.go b/expressions/expressions.go
@@ -53,6 +53,8 @@ func (e expression) Evaluate(ctx Context) (out interface{}, err error) {
 				err = e
 			case UndefinedFilter:
 				err = e
+			case FilterError:
+				err = e
 			default:
 				panic(r)
 			}

diff --git a/expressions/filters.go b/expressions/filters.go
@@ -21,6 +21,16 @@ func (e UndefinedFilter) Error() string {
 	return fmt.Sprintf("undefined filter %q", string(e))
 }
 
+// FilterError is the error returned by a filter when it is applied
+type FilterError struct {
+	FilterName string
+	Err        error
+}
+
+func (e FilterError) Error() string {
+	return fmt.Sprintf("error applying filter %q (%q)", e.FilterName, e.Err)
+}
+
 type valueFn func(Context) evaluator.Value
 
 // AddFilter adds a filter to the filter dictionary.