Struct ScanKeyCursor 

pub struct ScanKeyCursor { /* private fields */ }

A cursor to scan field/value pairs of a (hash) key.

It provides access via a closure given to ScanKeyCursor::for_each or if you need more control, you can use ScanKeyCursor::scan and implement your own loop, e.g. to allow an early stop.

Example usage

Here we show how to extract values to communicate them back to the Redis client. We assume that the following hash key is setup before:

HSET user:123 name Alice age 29 location Austin

The following example command implementation scans all fields and values in the hash key and returns them as an array of RedisString.

fn example_scan_key_for_each(ctx: &Context) -> RedisResult {
   let key = ctx.open_key_with_flags("user:123", KeyFlags::NOEFFECTS | KeyFlags::NOEXPIRE | KeyFlags::ACCESS_EXPIRED );
   let cursor  = ScanKeyCursor::new(key);

   let res = RefCell::new(Vec::new());
   cursor.for_each(|_key, field, value| {
       let mut res = res.borrow_mut();
       res.push(RedisValue::BulkRedisString(field.clone()));
       res.push(RedisValue::BulkRedisString(value.clone()));
   });

   Ok(RedisValue::Array(res.take()))
}

The method will produce the following output:

1) "name"
2) "Alice"
3) "age"
4) "29"
5) "location"
6) "Austin"

Implementations

impl ScanKeyCursor

pub fn new(key: RedisKey) -> Self

Creates a new scan cursor for the given key.

pub fn restart(&self)

Restarts the cursor from the beginning.

pub fn scan<F: FnMut(&RedisKey, &RedisString, &RedisString)>( &self, f: F, ) -> bool

Implements a call to RedisModule_ScanKey and calls the given closure for each callback invocation by ScanKey. Returns true if there are more fields to scan, false otherwise.

The callback may be called multiple times per RedisModule_ScanKey invocation.

Example

while cursor.scan(|_key, field, value| {
   // do something with field and value
}) {
  // do something between scans if needed, like an early stop
}

pub fn for_each<F: FnMut(&RedisKey, &RedisString, &RedisString)>(&self, f: F)

Implements a callback based for_each loop over all fields and values in the hash key. If you need more control, e.g. stopping after a scan invocation, then use ScanKeyCursor::scan directly.

Trait Implementations

impl Drop for ScanKeyCursor

fn drop(&mut self)

Executes the destructor for this type.