1 files changed, 81 insertions, 0 deletions
diff --git a/modern/src/form/LinkField.js b/modern/src/form/LinkField.js
new file mode 100644
index 00000000..b228fb34
--- /dev/null
+++ b/modern/src/form/LinkField.js
@@ -0,0 +1,81 @@
+import { FormControl, InputLabel, MenuItem, Select } from '@material-ui/core';
+import React, { useState } from 'react';
+import { useEffectAsync } from '../reactHelper';
+
+const LinkField = ({
+  margin,
+  variant,
+  label,
+  endpointAll,
+  endpointLinked,
+  baseId,
+  keyBase,
+  keyLink,
+  keyGetter = item => item.id,
+  titleGetter = item => item.name,
+}) => {
+  const [items, setItems] = useState();
+  const [linked, setLinked] = useState();
+
+  useEffectAsync(async () => {
+    const response = await fetch(endpointAll);
+    if (response.ok) {
+      setItems(await response.json());
+    }
+  }, []);
+
+  useEffectAsync(async () => {
+    const response = await fetch(endpointLinked);
+    if (response.ok) {
+      const data = await response.json();
+      setLinked(data.map(it => it.id));
+    }
+  }, []);
+
+  const createBody = linkId => {
+    const body = {};
+    body[keyBase] = baseId;
+    body[keyLink] = linkId;
+    return body;
+  }
+
+  const onChange = async event => {
+    const oldValue = linked;
+    const newValue = event.target.value;
+    for (const added of newValue.filter(it => !oldValue.includes(it))) {
+      await fetch('/api/permissions', {
+        method: 'POST',
+        headers: { 'Content-Type': 'application/json' },
+        body: JSON.stringify(createBody(added)),
+      });
+    }
+    for (const removed of oldValue.filter(it => !newValue.includes(it))) {
+      await fetch('/api/permissions', {
+        method: 'DELETE',
+        headers: { 'Content-Type': 'application/json' },
+        body: JSON.stringify(createBody(removed)),
+      });
+    }
+    setLinked(newValue);
+  };
+
+  if (items && linked) {
+    return (
+      <FormControl margin={margin} variant={variant}>
+        <InputLabel>{label}</InputLabel>
+        <Select
+          multiple
+          value={linked}
+          onChange={onChange}>
+          {items.map(item => (
+            <MenuItem key={keyGetter(item)} value={keyGetter(item)}>{titleGetter(item)}</MenuItem>
+          ))}
+        </Select>
+      </FormControl>
+    );
+  } else {
+    return null;
+  }
+}
+
+export default LinkField;