Merge pull request #4364 from Jaltaire/master

Add a skip_update field attribute for #[derive(AsChangeset)] (#860)

CHANGELOG.md

@@ -15,6 +15,7 @@ Increasing the minimal supported Rust version will always be coupled at least wi
 * Added `limit()` and `offset()` DSL to combination clauses such as `UNION`
 * Fixed `#[derive(Identifiable)]` ignoring attribute `#[diesel(serialize_as)]` on primary keys
 * Added embedded struct support for `AsChangeset` via `#[diesel(embed)]`
+* Added a `#[diesel(skip_update)]` attribute for the `AsChangeset` derive to skip updating a field present in the struct
 * Support for libsqlite3-sys 0.30.0
 * Add support for built-in PostgreSQL range operators and functions
 * Support for postgres multirange type

diesel_derives/src/as_changeset.rs

@@ -46,6 +46,10 @@ pub fn derive(item: DeriveInput) -> Result<TokenStream> {
     let mut ref_field_assign = Vec::with_capacity(fields_for_update.len());
 
     for field in fields_for_update {
+        // skip this field while generating the update
+        if field.skip_update() {
+            continue;
+        }
         // Use field-level attr. with fallback to the struct-level one.
         let treat_none_as_null = match &field.treat_none_as_null {
             Some(attr) => {

diesel_derives/src/attrs.rs

@@ -33,6 +33,7 @@ pub struct AttributeSpanWrapper<T> {
 pub enum FieldAttr {
     Embed(Ident),
     SkipInsertion(Ident),
+    SkipUpdate(Ident),
 
     ColumnName(Ident, SqlIdentifier),
     SqlType(Ident, TypePath),
@@ -145,6 +146,7 @@ impl Parse for FieldAttr {
         match &*name_str {
             "embed" => Ok(FieldAttr::Embed(name)),
             "skip_insertion" => Ok(FieldAttr::SkipInsertion(name)),
+            "skip_update" => Ok(FieldAttr::SkipUpdate(name)),
 
             "column_name" => Ok(FieldAttr::ColumnName(
                 name,
@@ -199,6 +201,7 @@ impl MySpanned for FieldAttr {
         match self {
             FieldAttr::Embed(ident)
             | FieldAttr::SkipInsertion(ident)
+            | FieldAttr::SkipUpdate(ident)
             | FieldAttr::ColumnName(ident, _)
             | FieldAttr::SqlType(ident, _)
             | FieldAttr::TreatNoneAsNull(ident, _)

diesel_derives/src/field.rs

@@ -18,6 +18,7 @@ pub struct Field {
     pub select_expression_type: Option<AttributeSpanWrapper<Type>>,
     pub embed: Option<AttributeSpanWrapper<bool>>,
     pub skip_insertion: Option<AttributeSpanWrapper<bool>>,
+    pub skip_update: Option<AttributeSpanWrapper<bool>>,
 }
 
 impl Field {
@@ -32,6 +33,7 @@ impl Field {
         let mut deserialize_as = None;
         let mut embed = None;
         let mut skip_insertion = None;
+        let mut skip_update = None;
         let mut select_expression = None;
         let mut select_expression_type = None;
         let mut treat_none_as_default_value = None;
@@ -111,6 +113,13 @@ impl Field {
                         ident_span,
                     })
                 }
+                FieldAttr::SkipUpdate(_) => {
+                    skip_update = Some(AttributeSpanWrapper {
+                        item: true,
+                        attribute_span,
+                        ident_span,
+                    })
+                }
             }
         }
 
@@ -138,6 +147,7 @@ impl Field {
             select_expression_type,
             embed,
             skip_insertion,
+            skip_update,
         })
     }
 
@@ -174,6 +184,10 @@ impl Field {
             .map(|a| a.item)
             .unwrap_or(false)
     }
+
+    pub(crate) fn skip_update(&self) -> bool {
+        self.skip_update.as_ref().map(|a| a.item).unwrap_or(false)
+    }
 }
 
 pub enum FieldName {

diesel_derives/src/lib.rs

@@ -111,6 +111,8 @@ mod valid_grouping;
 ///    the actual field type.
 /// * `#[diesel(treat_none_as_null = true/false)]`, overrides the container-level
 ///   `treat_none_as_null` attribute for the current field.
+/// * `#[diesel(skip_update)]`, skips updating this field. Useful for working with
+///    generated columns.
 #[cfg_attr(
     all(not(feature = "without-deprecated"), feature = "with-deprecated"),
     proc_macro_derive(

diesel_derives/tests/as_changeset.rs

@@ -891,3 +891,40 @@ fn embedded_struct() {
     let actual = users::table.order(users::id).load(connection);
     assert_eq!(Ok(expected), actual);
 }
+
+#[test]
+fn skip_update() {
+    let connection = &mut connection_with_sean_and_tess_in_users_table();
+
+    #[derive(AsChangeset)]
+    #[diesel(table_name = users)]
+    #[diesel(primary_key(name))]
+    #[allow(dead_code)]
+    struct UserForm<'a> {
+        #[diesel(skip_update)]
+        name: &'a str,
+        hair_color: &'a str,
+        r#type: &'a str,
+        #[diesel(skip_update)]
+        non_existing: i32,
+    }
+
+    diesel::update(users::table.find(1))
+        .set(UserForm {
+            name: "John",
+            hair_color: "green",
+            r#type: "admin",
+            non_existing: 42,
+        })
+        .execute(connection)
+        .unwrap();
+
+    let res = users::table
+        .find(1)
+        .first::<(i32, String, Option<String>, Option<String>)>(connection)
+        .unwrap();
+
+    assert_eq!(res.1, "Sean");
+    assert_eq!(res.2, Some("green".into()));
+    assert_eq!(res.3, Some("admin".into()));
+}