L5：在非对象上调用成员函数function（）

Got a resourceful controller with a __contruct function to declare $project

 public function __construct(Project $project){

    $this->project = $project;
}

Then I have an update and a destroy function which gives an Call to a member function delete() on a non-object (or update() error)

 public function edit($id)
{
    $project = $this->project->find($id);
    return view('project.edit', ['project' => $project, 'id' => 'edit']);
}


public function update(CreateProjectRequest $request, $project)
{
    $project->fill($request->input())->save();

    return redirect('project/index');
}


public function destroy($project)
{
    $project->delete();
    return redirect('project');
}

What am I doing wrong?

$project in this case is just the id of the project. You have to load it first:

public function destroy($projectId)
{
    $project = $this->project->findOrFail($projectId);
    $project->delete();
    return redirect('project');
}

Or just use the destroy method which takes the key as parameter:

public function destroy($projectId)
{
    $this->project->destroy($projectId);
    return redirect('project');
}

You might also want to look into Route Model Binding to fetch the model automatically from the DB.