I think this is what you are looking for:

The Actions column represents the default actions set. I added an specific button using custom column rendering (docs):
//..previous columns definition
{
title: "Custom Add",
field: "internal_action",
editable: false,
render: (rowData) =>
rowData && (
<IconButton
color="secondary"
onClick={() => addActionRef.current.click()}
>
<AddIcon />
</IconButton>
)
}
*Using rowData as conditional, prevents from rendering while filling the addition row.
Then I triggered the add action as shown here:
const MyComponent() {
const addActionRef = React.useRef();
return (
<>
<button onClick={() => addActionRef.current.click()}>
Add new item
</button>
<MaterialTable
//...
components={{
Action: props => {
//If isn't the add action
if (typeof props.action === typeof Function || props.action.tooltip !== 'Add') {
return <MTableAction {...props} />
} else {
return <div ref={addActionRef} onClick={props.action.onClick}/>;
}}
}}
editable={{
onRowAdd: (newData, oldData) => Promise.resolve(); //your callback here
}}
/>
</>
);
}
I extended the original snippet in order to complete the addition cycle. If you need to handle different types of actions, I think Editable section from the oficial docs would be handy.
Hope this works for you! Full code and sandbox here:
import React, { Fragment, useState } from "react";
import MaterialTable, { MTableAction } from "material-table";
import AddIcon from "@material-ui/icons/AddAlarm";
import IconButton from "@material-ui/core/IconButton";
export default function CustomEditComponent(props) {
const tableRef = React.createRef();
const addActionRef = React.useRef();
const tableColumns = [
{ title: "Client", field: "client" },
{ title: "Name", field: "name" },
{ title: "Year", field: "year" },
{
title: "Custom Add",
field: "internal_action",
editable: false,
render: (rowData) =>
rowData && (
<IconButton
color="secondary"
onClick={() => addActionRef.current.click()}
>
<AddIcon />
</IconButton>
)
}
];
const [tableData, setTableData] = useState([
{
client: "client1",
name: "Mary",
year: "2019"
},
{
client: "client2",
name: "Yang",
year: "2018"
},
{
client: "client3",
name: "Kal",
year: "2019"
}
]);
return (
<Fragment>
<MaterialTable
tableRef={tableRef}
columns={tableColumns}
data={tableData}
title="Custom Add Mode"
options={{
search: false
}}
components={{
Action: (props) => {
//If isn't the add action
if (
typeof props.action === typeof Function ||
props.action.tooltip !== "Add"
) {
return <MTableAction {...props} />;
} else {
return <div ref={addActionRef} onClick={props.action.onClick} />;
}
}
}}
actions={[
{
icon: "save",
tooltip: "Save User",
onClick: (event, rowData) => alert("You saved " + rowData.name)
}
]}
editable={{
onRowAdd: (newData) =>
Promise.resolve(setTableData([...tableData, newData]))
}}
/>
</Fragment>
);