survey_question_template.xml

<?xml version="1.0" encoding="utf-8"?>
<odoo>
    <!-- A page -->
    <template id="ethikis_survey_attachment_page" inherit_id="survey.page">
        <xpath expr="//div[@class='js_question-wrapper']/t[last()]" position="after">
            <t t-if="question.type == 'upload_file'"><t t-call="ethikis_survey_attachment.upload_file"/></t>
        </xpath>
    </template>

    <!-- Printable view of a survey (all pages) -->
    <template id="ethikis_survey_attachment_print" inherit_id="survey.survey_print">
        <xpath expr="//div[@class='js_question-wrapper']/t[last()]" position="after">
            <t t-if="question.type == 'upload_file'"><t t-call="ethikis_survey_attachment.upload_file"/></t>
        </xpath>
    </template>

    <!-- UPLOAD FILE TEMPLATE -->
    <template id="upload_file" name="Upload file">
        <div>
            <t t-if="user_input_line_upload_file">
                <t t-foreach="user_input_line_upload_file" t-as="upload_file" t-if="upload_file.question_id.id == question.id">
                    <a width="100px" height="100px" t-att-href="'data:%s;base64,%s' % (upload_file.file_type, to_text(upload_file.file))" target="_blank">Telecharger</a>
                </t>
            </t>
            <t t-else="">
                <div class="file-field" >
                    <input class="form-control" type="file" t-att-name="prefix"/>
                </div>
                <br/>
            </t>
        </div>

    </template>
</odoo>