Mutation and update cache

Now let's do the integration part. Open src/components/TodoItem.vue and add the following code to define the delete mutation

src/components/TodoItem.vue

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<script setup lang="ts">
import { useMutation } from "@vue/apollo-composable"
import { DELETE_TODOS_BY_PK, UPDATE_TODO_BY_PK } from "../graphql-operations"

const { todos, type } = defineProps(["todos", "type"])

const updateTodo = useMutation(UPDATE_TODO_BY_PK)

+ const deleteTodoByPk = useMutation(DELETE_TODOS_BY_PK, {
+     update: (cache, { data }) => {
+         cache.modify({
+             fields: {
+                 todos: (existingTodos, { readField }) => {
+                     return existingTodos.filter(
+                         (todoRef) => data.delete_todos_by_pk.id !== readField("id", todoRef)
+                     )
+                 },
+             },
+         })
+     },
+ })
</script>

We have a function defined to handle the button click to remove a todo. Let's update the code to use this deleteTodoByPk mutation:

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<template>
    <ul>
        <li v-for="todo in todos" v-bind:key="todo.id">
            <div v-if="todo.is_public" class="userInfoPublic">
                <p>@{{ todo.user.name }}</p>
            </div>
            <div class="view" v-if="type === 'private'">
                <div class="round">
                    <input type="checkbox" :id="todo.id" :checked="todo.is_completed" />
                    <label
                        @click="
                            updateTodo.mutate({
                                pk_columns: { id: todo.id },
                                _set: { is_completed: !todo.is_completed },
                            })
                        "
                        :htmlFor="todo.id"
                    />
                </div>
            </div>
            <div class="labelContent">
                <p :style="todo.is_completed ? 'text-decoration: strikethrough' : ''">
                    {{ todo.title }}
                </p>
            </div>
-            <button v-if="type === 'private'" class="closeBtn">x</button>
+            <button
+                v-if="type === 'private'"
+                @click="deleteTodoByPk.mutate({ id: todo.id })"
+                class="closeBtn"
+            >
+                x
+            </button>
        </li>
    </ul>
</template>

Again, we are making a mutation to delete a todo and update the cache. This pattern should be familiar enough by now.