Key-Value Storage

Key-value actions store and retrieve values by key. This is useful for caching frequently accessed data, passing state between workflow executions, and implementing cache-aside patterns.

This storage is persistent — values survive a server restart. It is a simple key-value store, not a replacement for a database: for structured, queryable data use Data Operations.

This is unrelated to an agent’s accessMemory setting, which gives an agent file tools over its workspace. See AI Agents.

store_key

Stores a key-value pair in persistent storage.

Key

The unique identifier for storing the data. Use template syntax to create dynamic keys.


YAML Key	`key`
Type	string
Required	Yes

Include unique identifiers in your keys to avoid collisions. For example: user_{{ param "user_id" }} or cache_{{ .request_hash }}.

Value

The data to store. Can be any value, including JSON objects.


YAML Key	`value`
Type	string
Required	Yes

Use {{ jsonout .action_result }} to store complex objects from previous actions.

Output

{{ .step_id }} holds the value that was stored.

Example

Store a user object:

actions:
  cache_user:
    type: store_key
    config:
      key: "user_{{ param \"user_id\" }}"
      value: "{{ jsonout .fetch_user }}"
    next: response.success

Store a computed value:

actions:
  store_token:
    type: store_key
    config:
      key: "auth_token_{{ .user.id }}"
      value: "{{ .generate_token }}"
    next: action.use_token

get_key

Retrieves a value from persistent storage by key.

Key

The key to look up.


YAML Key	`key`
Type	string
Required	Yes

Fail If Empty

Whether to fail the step when the key is not set. When false, a missing key yields an empty result and the workflow continues.


YAML Key	`failIfEmpty`
Type	boolean
Required	No
Default	`false`

Output

{{ .step_id }} holds the stored value, or is empty when the key is not set.

Example

Retrieve a cached user:

actions:
  get_cached_user:
    type: get_key
    config:
      key: "user_{{ param \"user_id\" }}"
    next: conditional.cache_hit

Require the key to exist:

actions:
  load_config:
    type: get_key
    config:
      key: "app_config"
      failIfEmpty: true
    next: action.apply_config
    fail: response.not_configured

Common Patterns

Cache-Aside Pattern

Check the cache first, fetch from the database if not found, then update the cache:

actions:
  check_cache:
    type: get_key
    config:
      key: "data_{{ param \"id\" }}"
    next: conditional.is_cached

conditionals:
  is_cached:
    expression: "{{ notempty .check_cache \"\" }}"
    onTrue: response.from_cache
    onFalse: action.fetch_from_db

actions:
  fetch_from_db:
    type: fetch
    config:
      integration: my_database
      table: data
      filters:
        - field: id
          operator: eq
          value: "{{ param \"id\" }}"
      single: true
    next: action.update_cache

  update_cache:
    type: store_key
    config:
      key: "data_{{ param \"id\" }}"
      value: "{{ jsonout .fetch_from_db }}"
    next: response.success

responses:
  from_cache:
    statusCode: 200
    body:
      source: "cache"
      data: "{{ .check_cache }}"

  success:
    statusCode: 200
    body:
      source: "database"
      data: "{{ .fetch_from_db }}"

Session Storage

Store and retrieve user session data:

actions:
  store_session:
    type: store_key
    config:
      key: "session_{{ param \"session_id\" }}"
      value: |
        {
          "user_id": "{{ .authenticated_user.id }}",
          "login_time": "{{ now }}",
          "preferences": {{ jsonout .user_preferences }}
        }
    next: response.session_created

actions:
  get_session:
    type: get_key
    config:
      key: "session_{{ param \"session_id\" }}"
    next: conditional.session_valid

conditionals:
  session_valid:
    expression: "{{ notempty .get_session \"\" }}"
    onTrue: action.process_request
    onFalse: response.session_expired

Rate Limiting Counter

Track request counts for rate limiting:

actions:
  get_request_count:
    type: get_key
    config:
      key: "rate_{{ param \"api_key\" }}"
    next: action.increment_count

  increment_count:
    type: javascript
    config:
      script: |
        function servflowRun(vars) {
          const current = parseInt(vars.get_request_count) || 0;
          return current + 1;
        }
    next: action.store_count

  store_count:
    type: store_key
    config:
      key: "rate_{{ param \"api_key\" }}"
      value: "{{ .increment_count }}"
    next: conditional.check_limit

conditionals:
  check_limit:
    expression: "{{ lt .increment_count 100 }}"
    onTrue: action.process_request
    onFalse: response.rate_limited

Temporary Token Storage

Store and validate temporary tokens:

actions:
  generate_reset_token:
    type: javascript
    config:
      script: |
        function servflowRun(vars) {
          return Math.random().toString(36).substring(2, 15);
        }
    next: action.store_reset_token

  store_reset_token:
    type: store_key
    config:
      key: "reset_{{ .generate_reset_token }}"
      value: |
        {
          "user_id": "{{ .fetch_user.id }}",
          "email": "{{ .fetch_user.email }}",
          "created_at": "{{ now }}"
        }
    next: action.send_reset_email

actions:
  validate_reset_token:
    type: get_key
    config:
      key: "reset_{{ param \"token\" }}"
    next: conditional.token_valid

conditionals:
  token_valid:
    expression: "{{ notempty .validate_reset_token \"\" }}"
    onTrue: action.allow_password_reset
    onFalse: response.invalid_token

Best Practices

Key Naming: Use consistent key naming conventions with prefixes to organize your data. For example: user_, session_, cache_, rate_.

Data Size: Keep stored values reasonably sized. For large datasets, consider storing only essential fields or IDs and fetching full data when needed.

No TTL: This store doesn’t support automatic expiration. Implement your own expiration logic by storing timestamps and checking them during retrieval.

Next Steps

Data Operations

Use a database for structured, queryable data.

Transformation

Process and transform cached data with JavaScript.

Flow Control

Combine caching with parallel data fetching.

Actions Overview

Learn the fundamentals of ServFlow actions.

Getting Started

Quickstart

Running ServFlow

Concepts

References

store_key

Key

Value

Output

Example

get_key

Key

Fail If Empty

Output

Example

Common Patterns

Cache-Aside Pattern

Session Storage

Rate Limiting Counter

Temporary Token Storage

Best Practices

Next Steps

Data Operations

Transformation

Flow Control

Actions Overview

​store_key

​Key

​Value

​Output

​Example

​get_key

​Key

​Fail If Empty

​Output

​Example

​Common Patterns

​Cache-Aside Pattern

​Session Storage

​Rate Limiting Counter

​Temporary Token Storage

​Best Practices

​Next Steps

Data Operations

Transformation

Flow Control

Actions Overview

store_key

Key

Value

Output

Example

get_key

Key

Fail If Empty

Output

Example

Common Patterns

Cache-Aside Pattern

Session Storage

Rate Limiting Counter

Temporary Token Storage

Best Practices

Next Steps