Auto-Complete in AMP with POST method - ruby-on-rails

Question

I have a problem in AMP page. I want to build a page with AutoComplete list selection like jquery AutoComplete.
Amp give Example for Autocomplete Selection. But there is a problem. I have API with POST Method in this example I don't know how to set Request method Post in it with a different origin.
<div class="form-item city-state">
<label>City</label>
<input name="city"
type="text"
on="
input-debounced:
AMP.setState({
query: event.value,
showDropdown: event.value,
}),
autosuggest-list.show;
tap:
AMP.setState({
query: query == null ? '' : query,
showDropdown: 'true'
}),
autosuggest-list.show"
[value]="query || ''"
value=""
required
autocomplete="off" />
</div>
<div class="suggest">
<div class="autosuggest-container hidden"
[class]="(showDropdown && query) ?
'autosuggest-container' :
'autosuggest-container hidden'">
<amp-list class="autosuggest-box"
layout="fixed-height"
height="120"
src="/advanced/autosuggest/search_list"
[src]="query ?
autosuggest.endpoint + query :
autosuggest.emptyAndInitialTemplateJson"
id="autosuggest-list">
<template type="amp-mustache">
<amp-selector id="autosuggest-selector"
keyboard-select-mode="focus"
layout="container"
on="
select:
AMP.setState({
query: event.targetOption,
showDropdown: false
}),
autosuggest-list.hide">
{{#results}}
<div class="select-option no-outline"
role="option"
tabindex="0"
on="tap:autosuggest-list.hide"
option="{{.}}">{{.}}</div>
{{/results}} {{^results}}
<div class="select-option {{#query}}empty{{/query}}">
{{#query}}Sorry! We don't ship to your city 😰{{/query}}
</div>
{{/results}}
</amp-selector>
</template>
</amp-list>
</div>
</div>
<amp-state id="autosuggest">
<script type="application/json">
{
"endpoint": "/advanced/autosuggest/search_list?q=",
"emptyAndInitialTemplateJson": [{
"query": "",
"results": []
}]
}
</script>
</amp-state>