1 files changed, 45 insertions, 1 deletions

diff --git a/src/client/views/MetadataEntryMenu.tsx b/src/client/views/MetadataEntryMenu.tsx
index 59de0e2b4..08abb9887 100644
--- a/src/client/views/MetadataEntryMenu.tsx
+++ b/src/client/views/MetadataEntryMenu.tsx
@@ -3,7 +3,7 @@ import "./MetadataEntryMenu.scss";
 import { observer } from 'mobx-react';
 import { observable, action, runInAction, trace } from 'mobx';
 import { KeyValueBox } from './nodes/KeyValueBox';
-import { Doc } from '../../new_fields/Doc';
+import { Doc, Field } from '../../new_fields/Doc';
 import * as Autosuggest from 'react-autosuggest';
 
 export type DocLike = Doc | Doc[] | Promise<Doc> | Promise<Doc[]>;
@@ -18,17 +18,60 @@ export class MetadataEntryMenu extends React.Component<MetadataEntryProps>{
     @observable private _currentKey: string = "";
     @observable private _currentValue: string = "";
     @observable private suggestions: string[] = [];
+    private userModified = false;
 
     private autosuggestRef = React.createRef<Autosuggest>();
 
     @action
     onKeyChange = (e: React.ChangeEvent, { newValue }: { newValue: string }) => {
         this._currentKey = newValue;
+        if (!this.userModified) {
+            this.previewValue();
+        }
+    }
+
+    previewValue = async () => {
+        let field: Field | undefined | null = null;
+        let onProto: boolean = false;
+        let value: string | undefined = undefined;
+        let docs = this.props.docs;
+        if (typeof docs === "function") {
+            if (this.props.suggestWithFunction) {
+                docs = docs();
+            } else {
+                return;
+            }
+        }
+        docs = await docs;
+        if (docs instanceof Doc) {
+            await docs[this._currentKey];
+            value = Field.toKeyValueString(docs, this._currentKey);
+        } else {
+            for (const doc of docs) {
+                const v = await doc[this._currentKey];
+                onProto = onProto || !Object.keys(doc).includes(this._currentKey);
+                if (field === null) {
+                    field = v;
+                } else if (v !== field) {
+                    value = "multiple values";
+                }
+            }
+        }
+        if (value === undefined) {
+            if (field !== null && field !== undefined) {
+                value = (onProto ? "" : "= ") + Field.toScriptString(field);
+            } else {
+                value = "";
+            }
+        }
+        const s = value;
+        runInAction(() => this._currentValue = s);
     }
 
     @action
     onValueChange = (e: React.ChangeEvent<HTMLInputElement>) => {
         this._currentValue = e.target.value;
+        this.userModified = e.target.value.trim() !== "";
     }
 
     onValueKeyDown = async (e: React.KeyboardEvent) => {
@@ -64,6 +107,7 @@ export class MetadataEntryMenu extends React.Component<MetadataEntryProps>{
     clearInputs = () => {
         this._currentKey = "";
         this._currentValue = "";
+        this.userModified = false;
         if (this.autosuggestRef.current) {
             const input: HTMLInputElement = (this.autosuggestRef.current as any).input;
             input && input.focus();