From 2a9800a84927e0d18050e4db665deb64db9d1e8c Mon Sep 17 00:00:00 2001
From: Michael Gaffney <mike@gaffney.cc>
Date: Wed, 3 Jun 2020 09:25:07 -0400
Subject: [PATCH] Add function to check if db error is a check constraint
 violation

---
 internal/db/error.go      | 17 +++++++++++++++++
 internal/db/error_test.go | 39 ++++++++++++++++++++++++++++++++++++++-
 2 files changed, 55 insertions(+), 1 deletion(-)

diff --git a/internal/db/error.go b/internal/db/error.go
index f88d7ec5cc..49004ab5bf 100644
--- a/internal/db/error.go
+++ b/internal/db/error.go
@@ -58,3 +58,20 @@ func IsUniqueError(err error) bool {
 
 	return false
 }
+
+// IsCheckConstraintError returns a boolean indicating whether the error is
+// known to report a check constraint violation.
+func IsCheckConstraintError(err error) bool {
+	if err == nil {
+		return false
+	}
+
+	var pqError *pq.Error
+	if errors.As(err, &pqError) {
+		if pqError.Code.Name() == "check_violation" {
+			return true
+		}
+	}
+
+	return false
+}
diff --git a/internal/db/error_test.go b/internal/db/error_test.go
index b31b2f3762..efed0f6c74 100644
--- a/internal/db/error_test.go
+++ b/internal/db/error_test.go
@@ -26,7 +26,7 @@ func TestError_IsUnique(t *testing.T) {
 			want: false,
 		},
 		{
-			name: "postgres-is-unique2",
+			name: "postgres-is-unique",
 			in: &pq.Error{
 				Code: pq.ErrorCode("23505"),
 			},
@@ -43,3 +43,40 @@ func TestError_IsUnique(t *testing.T) {
 		})
 	}
 }
+
+func TestError_IsCheckConstraint(t *testing.T) {
+	var tests = []struct {
+		name string
+		in   error
+		want bool
+	}{
+		{
+			name: "nil-error",
+			in:   nil,
+			want: false,
+		},
+		{
+			name: "postgres-not-check-constraint",
+			in: &pq.Error{
+				Code: pq.ErrorCode("23505"),
+			},
+			want: false,
+		},
+		{
+			name: "postgres-is-check-constraint",
+			in: &pq.Error{
+				Code: pq.ErrorCode("23514"),
+			},
+			want: true,
+		},
+	}
+	for _, tt := range tests {
+		tt := tt
+		t.Run(tt.name, func(t *testing.T) {
+			assert := assert.New(t)
+			err := tt.in
+			got := IsCheckConstraintError(err)
+			assert.Equal(tt.want, got)
+		})
+	}
+}