Created
January 10, 2022 10:41
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hooks mutations - saving
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| <TodoContext.Provider | |
| value={{ | |
| save: () => { | |
| // contrived code for the demonstration | |
| // in the real app this was responsible for deciding if a request should be sent to server or not | |
| const existingTodoKeys = Array.from(existingTodos().keys()); | |
| const draftTodoKeys = Array.from(draftTodos.keys()); | |
| let todosHasChanges = existingTodoKeys.length !== draftTodoKeys.length; | |
| // now check entries using ids, unless we know they have changed based on length | |
| // there are better ways of detecting changes but this demonstrates the issue | |
| if (!todosHasChanges) { | |
| const existingTodoValues = Array.from(existingTodos().values()); | |
| const draftTodoValues = Array.from(draftTodos.values()); | |
| for (let todoIndex = 0; todoIndex < draftTodoKeys.length; todoIndex++) { | |
| // now check each entry | |
| if ( | |
| existingTodoKeys[todoIndex] !== draftTodoKeys[todoIndex] || | |
| existingTodoValues[todoIndex].done !== | |
| draftTodoValues[todoIndex].done | |
| ) { | |
| todosHasChanges = true; | |
| break; | |
| } | |
| } | |
| } | |
| if (todosHasChanges) { | |
| // send off request to server | |
| } | |
| }, | |
| }} | |
| > | |
| {children} | |
| </TodoContext.Provider> |
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