Put Compare Exchange Operation

// Create a new CmpXchg item:
// ==========================

// Define the put compare-exchange operation. Pass:
// * KEY: a new unique identifier (e.g. a user's email)
// * VALUE: an associated value (e.g. the user's name)
// * INDEX: pass '0' to indicate that this is a new key
const putCmpXchgOp = new PutCompareExchangeValueOperation("johnDoe@gmail.com", "John Doe", 0);

// Execute the operation by passing it to operations.send
const result = await documentStore.operations.send(putCmpXchgOp);

// Check results
const successful = result.successful; // Has operation succeeded
const indexForItem = result.index;    // The version number assigned to the new item

// If successful is true then a new compare-exchange item has been created
// with the unique email key and the associated value.

• Note:
  Using 0 with a key that already exists will Not modify existing compare-exchange item.

// Create a new CmpXchg item with metadata:
// ========================================

// Define the put compare-exchange operation.
// Pass a 4'th parameter with the metadata object.
const putCmpXchgOp = new PutCompareExchangeValueOperation("+48-123-456-789", "John Doe", 0,
    { 
        "Provider": "T-Mobile",
        "Network": "5G",
        "Work phone": false
    });

// Execute the operation by passing it to operations.send
const result = await documentStore.operations.send(putCmpXchgOp);

// Check results
const successful = result.successful; // Has operation succeeded
const indexForItem = result.index;    // The version number assigned to the new item

// If successful is true then a new compare-exchange item has been created
// with the unique phone number key, value, and metadata.

• Find more examples of adding metadata to a compare-exchange item in compare-exchange metadata.

• When calling PutCompareExchangeValueOperation,
  the index from the request is compared to the index that is currently stored in the server for the specified key.
• The compare-exchange item is updated only if the two are equal.

// Modify an existing CmpXchg item:
// ================================

// Get the existing compare-exchange item
const item = await documentStore.operations.send(
    new GetCompareExchangeValueOperation("+48-123-456-789")
);

// Make some changes
const newValue = "Jane Doe";
const metadata = item.metadata;
metadata["Work phone"] = true;

// Update the compare-exchange item:
// The put operation will succeed only if the 'index' of the compare-exchange item
// has not changed between the read and write operations.
const result = await documentStore.operations.send(
    new PutCompareExchangeValueOperation("+48-123-456-789", newValue, item.index, metadata)
);

// Check results
const successful = result.successful; // Has operation succeeded
const newIndex = result.index;        // The new version number assigned to the item 

// Version has increased
assert(newIndex > item.index);

// Available overloads:
// ====================
const putCmpXchgOp = new PutCompareExchangeValueOperation(key, value, index);
const putCmpXchgOp = new PutCompareExchangeValueOperation(key, value, index, metadata);

// Return value of store.operations.send(putCmpXchgOp)
// ===================================================
class CompareExchangeResult {
    successful;
    value;
    index;
}