Data Source

Table of contents

Memento Database offers several ways to automatically fill entry fields (Autofill feature). One of these ways is using Custom Data Sources - a powerful scripting mechanism that allows you to fetch data from virtually any source

Custom Data Sources give you the most flexibility by allowing you to:

  • Connect to any web API or service
  • Query other Memento libraries with complex logic
  • Process and transform data before filling fields
  • Implement custom search and data retrieval logic
  • Combine multiple data sources

Query

When a user enters a search term, Memento automatically makes it available in your script through the global variable query. This variable contains:

  • The text entered by the user (for text searches)
  • The scanned barcode (for barcode searches)

How Custom Data Sources Work

Basic Flow

  1. User enters a search term in an entry field
  2. The custom data source script runs using this search term (automatically available as the global variable query)
  3. Script processes the search and must return results using the global result() method
  4. The result() method expects an array of objects with this structure: 
    {
    title: "Display Name",     // Required - shown as main text
    desc: "Description",       // Optional - shown as subtitle
    thumb: "image_url",        // Optional - shown as thumbnail
    id: "identifier",          // Required for additional data fetch
    // ... any other properties for field mapping
}
  5. Memento displays these objects to the user in a selection list
  6. User selects the desired result
  7. Selected object’s properties are mapped to entry fields according to defined rules

Advanced Flow (with Additional Data)

Some data sources can fetch additional details after the initial search. In this case:

  1. Initial search returns basic information (title, description, etc.)
  2. User selects an item
  3. Script fetches detailed information for the selected item
  4. Memento fills entry fields with the complete data

Setting Up a Custom Data Source

1. Create the Data Source

  1. Open the Library Edit screen
  2. Navigate to the Autofill tab
  3. Click the “+” button
  4. Choose the search type:
    • By Name (text search)
    • By Barcode (barcode scanner)
  5. Select “Custom source”
  6. Choose the field to use for searching

2. Write the Script

Scripts must return data in a specific format. Here’s a basic template:

// Basic search script
var results = [
    {
        title: "Item Name",        // Required
        desc: "Description",       // Optional
        thumb: "image_url",        // Optional
        id: "unique_identifier"    // Required for additional data fetch
    }
];
result(results);

// With additional data fetch
result(results, function(id) {
    // Fetch and return additional data
    return additionalData;
});

3. Map Data to Fields

After creating the script:

  1. Close the script editor
  2. Click “+” to add field mappings
  3. Enter the property name from your result object
  4. Select the corresponding library field
  5. Repeat for each field you want to populate

Script Requirements

Result Object Properties

  • title (required): Display name of the item
  • desc (optional): Additional description
  • thumb (optional): URL or reference to an image
  • id (required for additional data): Unique identifier

The result() Function 

result(sourceObjects, getMoreFunction)
  • sourceObjects: Array of objects matching the search
  • getMoreFunction: Optional function to fetch additional data

Scripts run with the same security context as triggers

Examples

Fetch Data from Another Library 

var anotherLib = libByName("AnotherLib");         
var entries = anotherLib.find(query);
var resultArray = [];
for(var i in entries ) {
   var object = {};
   object["title"] = entries[i].title;
   object["desc"] = entries[i].description;
   object["number"] = entries[i].field("Number");
   resultArray.push(object);
   }
result(resultArray);

Web API Integration 

// Example using a REST API
var response = http().get("https://api.example.com/search?q=" + 
    encodeURIComponent(query));
    
result(
    JSON.parse(response),
    function(id) {
        return http().get("https://api.example.com/items/" + id);
    }
);