But first, let's check some small concepts.

## In a hurry? { #in-a-hurry }

If you don't care about any of these terms and you just need to add security with authentication based on username and password *right now*, skip to the next chapters.

## OAuth2 { #oauth2 }

OAuth2 is a specification that defines several ways to handle authentication and authorization.

You can create production applications with **FastAPI** right now (and you have probably been doing it for some time), you just have to make sure that you use a version that works correctly with the rest of your code.

## Pin your `fastapi` version { #pin-your-fastapi-version }

}

// JoinNestedRelationNames nested relationships like `Manager__Company`
func JoinNestedRelationNames(relationNames []string) string {
	return strings.Join(relationNames, nestedRelationSplit)
}

// RTrimSlice Right trims the given slice by given length
func RTrimSlice[T any](v []T, trimLen int) []T {
	if trimLen >= len(v) { // trimLen greater than slice len means fully sliced
		return v[:0]
	}

                        </h1>
                    </div>
                    <div class="col-sm-6">
                        <ol class="breadcrumb float-sm-right">
                            <li class="breadcrumb-item"><la:link href="list">
                                <la:message key="labels.elevate_word_link_list"/>
                            </la:link></li>

						<div class="col-sm-6">
							<h1>
								<la:message key="labels.storage_configuration" />
							</h1>
						</div>
						<div class="col-sm-6">
							<ol class="breadcrumb float-sm-right">
								<li class="breadcrumb-item"><la:link href="/admin/storage/">
										<la:message key="labels.crud_link_list" />
									</la:link></li>

---

If you just don't know, use normal `def`.

---

**Note**: You can mix `def` and `async def` in your *path operation functions* as much as you need and define each one using the best option for you. FastAPI will do the right thing with them.

Anyway, in any of the cases above, FastAPI will still work asynchronously and be extremely fast.

But by following the steps above, it will be able to do some performance optimizations.

                            <la:message key="labels.dict_mapping_title"/>
                        </h1>
                    </div>
                    <div class="col-sm-6">
                        <ol class="breadcrumb float-sm-right">
                            <li class="breadcrumb-item"><la:link href="/admin/dict">
                                <la:message key="labels.dict_list_link"/>
                            </la:link></li>

                    <c:if test="${!displayCreateLink}">
                        <la:link href="/admin/fileconfig/" styleClass="btn btn-primary ${f:h(editableClass)}">
                            <em class="fa fa-arrow-circle-right">
                            <la:message key="labels.file_auth_create_file_config"/>
                        </la:link>
                    </c:if>
                    <c:if test="${displayCreateLink}">

                            <la:message key="labels.joblog_configuration"/>
                        </h1>
                    </div>
                    <div class="col-sm-6">
                        <ol class="breadcrumb float-sm-right">
                            <li class="breadcrumb-item active"><la:link href="/admin/joblog">
                                <la:message key="labels.joblog_link_list"/>
                            </la:link></li>

                            <la:message key="labels.joblog_title_details"/>
                        </h1>
                    </div>
                    <div class="col-sm-6">
                        <ol class="breadcrumb float-sm-right">
                            <li class="breadcrumb-item"><la:link href="/admin/crawlinginfo">
                                <la:message key="labels.joblog_link_list"/>
                            </la:link></li>