How to use the flask.request.form.get function in Flask

def oauth_token():
    """
    OAuth2 server -- token endpoint (confidential clients only)
    """
    # Always required parameters
    grant_type = request.form.get('grant_type')
    auth_client = current_auth.auth_client  # Provided by @requires_client_login
    scope = request.form.get('scope', '').split(' ')
    # if grant_type == 'authorization_code' (POST)
    code = request.form.get('code')
    redirect_uri = request.form.get('redirect_uri')
    # if grant_type == 'password' (POST)
    username = request.form.get('username')
    password = request.form.get('password')
    # if grant_type == 'client_credentials'
    buid = request.form.get('buid') or request.form.get(
        'userid'
    )  # XXX: Deprecated userid parameter

    # Validations 1: Required parameters
    if not grant_type:
        return oauth_token_error('invalid_request', _("Missing grant_type"))
    # grant_type == 'refresh_token' is not supported. All tokens are permanent unless revoked
    if grant_type not in ['authorization_code', 'client_credentials', 'password']:
        return oauth_token_error('unsupported_grant_type')

    # Validations 2: client scope
    if grant_type == 'client_credentials':
        # AuthClient data; user isn't part of it OR trusted client and automatic scope

def route_create_ensemble_workflow(ensemble):
    dao = Ensembles(g.session)
    e = dao.get_ensemble(g.user.username, ensemble)

    name = request.form.get("name", None)
    if name is None:
        raise EMError("Specify ensemble workflow 'name'")

    priority = request.form.get("priority", 0)

    basedir = request.form.get("basedir")
    if basedir is None:
        raise EMError("Specify 'basedir' where plan command should be executed")

    plan_command = request.form.get("plan_command")
    if plan_command is None:
        raise EMError("Specify 'plan_command' that should be executed to plan workflow")

    dao.create_ensemble_workflow(e.id, name, basedir, priority, plan_command)

    g.session.commit()

    return api.json_created(url_for("route_get_ensemble_workflow", ensemble=ensemble, workflow=name))

def clear(self):
        dag_id = request.form.get('dag_id')
        task_id = request.form.get('task_id')
        origin = request.form.get('origin')
        dag = dagbag.get_dag(dag_id)

        execution_date = request.form.get('execution_date')
        execution_date = timezone.parse(execution_date)
        confirmed = request.form.get('confirmed') == "true"
        upstream = request.form.get('upstream') == "true"
        downstream = request.form.get('downstream') == "true"
        future = request.form.get('future') == "true"
        past = request.form.get('past') == "true"
        recursive = request.form.get('recursive') == "true"
        only_failed = request.form.get('only_failed') == "true"

        dag = dag.sub_dag(
            task_regex=r"^{0}$".format(task_id),
            include_downstream=downstream,
            include_upstream=upstream)

        end_date = execution_date if not future else None
        start_date = execution_date if not past else None

        return self._clear_dag_tis(dag, start_date, end_date, origin,
                                   recursive=recursive, confirmed=confirmed, only_failed=only_failed)

def upload_file():
    return str(len(request.form.get('pippo', 'boh'))) + request.form.get('pippo', 'boh')
    return request.files['ufile'].read()

def create():
    if request.method == 'POST':  # if the method is 'POST' we know the form sent us to this page, so there is data to process.
        title = request.form.get('title')
        content = request.form.get('content')
        post_id = len(posts)
        posts[post_id] = {'id': post_id, 'title': title, 'content': content}

        return redirect(url_for('post', post_id=post_id))
    # if we are here it means we did not redirect to the post; so we must've loaded this using a GET.
    # the browser always sends GET, so this means the user wants to load the page (as opposed to giving us data via the form).
    # We can render the form.
    return render_template('create.jinja2')

def register():
    if request.method=='GET':
        return render_template('register.html')
    else:
        stu_id = request.form.get('stu_id')
        user = request.form.get('user')
        password = request.form.get('password')
        password1 = request.form.get('password1')
        print(stu_id, user, password, password1)

        if(password1 != password):
            return u'两次输入密码不同，请检查'
        else:
            sql = "select * from STUDENT where STU_NO = '%s'" % stu_id
            print(sql)
            result = query.query(sql)
            print(result)
            if len(result) != 0:
                return u'已经有这个用户了'
            else:
                sql = "INSERT INTO STUDENT VALUES('%s', 'SEX', '%s', 'COLLEGE', 'MAJOR', 'AD_YEAR', '%s', 'ID')" % (user, stu_id, password)
                print(sql)
                query.update(sql)

def __get_input_model_for_tx() -> AccountTransactionsInputModel:
    """ Parse user input or create a blank input model """
    model = AccountTransactionsInputModel()

    if request.args:
        # model.account_id = request.args.get('account')
        model.period = request.args.get('period')

    if request.form:
        # read from request
        model.account_id = request.form.get('account')
        model.period = request.form.get('period')

    return model

def home():
    text = request.form.get('text', '') or request.args.get('text', '')
    return render_template(
        'home.html',
        languages=sorted(
            UI_LANGUAGES_MAP.items(),
            key=lambda key_val: key_val[1],
        ),
        text=text,
        extra_html_classes='start-on-paste' if (text or 'text' in request.args) else '',
        icon_extensions=ICON_EXTENSIONS,
        max_upload_size=app.config['MAX_UPLOAD_SIZE'],
    )

if request.method == 'GET':

        invoice = getInvoice(session.book, id)
        
        if invoice is None:
            abort(404)
        else:
            return Response(json.dumps(invoice), mimetype='application/json')

    elif request.method == 'POST':

        customer_id = str(request.form.get('customer_id', ''))
        currency = str(request.form.get('currency', ''))
        date_opened = request.form.get('date_opened', None)
        notes = str(request.form.get('notes', ''))
        posted = request.form.get('posted', None)
        posted_account_guid = str(request.form.get('posted_account_guid', ''))
        posted_date = request.form.get('posted_date', '')
        due_date = request.form.get('due_date', '')
        posted_memo = str(request.form.get('posted_memo', ''))
        posted_accumulatesplits = request.form.get('posted_accumulatesplits',
            '')
        posted_autopay = request.form.get('posted_autopay', '')

        if posted == '1':
            posted = 1
        else:
            posted = 0

        if (posted_accumulatesplits == '1'
            or posted_accumulatesplits == 'true'

def create_mod():
    if not current_user:
        return { 'error': True, 'reason': 'You are not logged in.' }, 401
    if not current_user.public:
        return { 'error': True, 'reason': 'Only users with public profiles may create mods.' }, 403
    name = request.form.get('name')
    short_description = request.form.get('short-description')
    version = request.form.get('version')
    ksp_version = request.form.get('ksp-version')
    license = request.form.get('license')
    ckan = request.form.get('ckan')
    zipball = request.files.get('zipball')
    # Validate
    if not name \
        or not short_description \
        or not version \
        or not ksp_version \
        or not license \
        or not zipball:
        return { 'error': True, 'reason': 'All fields are required.' }, 400
    # Validation, continued
    if len(name) > 100 \
        or len(short_description) > 1000 \
        or len(license) > 128: