patcho.patch
A simple version migration system for Clojure applications.
Patcho provides a declarative way to define version-based patches that can be applied to migrate between different versions of your application or modules.
Key features:
- Automatic patch sequencing based on semantic versioning
- Support for both upgrades and downgrades
- Topic-based organization for modular systems
- Simple macro-based API
Basic usage: (require '[patcho.patch :as patch])
; Define current version (patch/current-version ::my-app "2.0.0")
; Define upgrade patches (patch/upgrade ::my-app "1.0.0" (println "Initial setup"))
(patch/upgrade ::my-app "2.0.0" (println "Major upgrade"))
; Apply patches (patch/apply ::my-app "1.0.0") ; Runs 2.0.0 upgrade (patch/apply ::my-app nil) ; Runs all upgrades
A simple version migration system for Clojure applications.
Patcho provides a declarative way to define version-based patches that can be
applied to migrate between different versions of your application or modules.
Key features:
- Automatic patch sequencing based on semantic versioning
- Support for both upgrades and downgrades
- Topic-based organization for modular systems
- Simple macro-based API
Basic usage:
(require '[patcho.patch :as patch])
; Define current version
(patch/current-version ::my-app "2.0.0")
; Define upgrade patches
(patch/upgrade ::my-app "1.0.0"
(println "Initial setup"))
(patch/upgrade ::my-app "2.0.0"
(println "Major upgrade"))
; Apply patches
(patch/apply ::my-app "1.0.0") ; Runs 2.0.0 upgrade
(patch/apply ::my-app nil) ; Runs all upgrades_downgradecljmultimethod
_upgradecljmultimethod
applyclj
(apply topic)(apply topic current)(apply topic current target)Applies version patches to migrate from one version to another.
With 1 args: Migrates from 'last-deployed-version' to the topic's defined current version. With 2 args: Migrates from 'current' to the topic's defined current version. With 3 args: Migrates from 'current' to 'target' version.
Arguments:
topic - Keyword identifying the module/component to patch
current - Current version string (nil or "0" means start from beginning)
target - Target version string (optional, defaults to topic's current version)
The function automatically:
- Determines upgrade vs downgrade direction
- Finds applicable patches between versions
- Executes patches in correct order (oldest-first for upgrades, newest-first for downgrades)
Example: (apply ::my-app "1.0.0" "2.0.0") ; Upgrade from 1.0.0 to 2.0.0 (apply ::my-app "2.0.0" "1.0.0") ; Downgrade from 2.0.0 to 1.0.0 (apply ::my-app nil) ; Upgrade from beginning to current
Applies version patches to migrate from one version to another. With 1 args: Migrates from 'last-deployed-version' to the topic's defined current version. With 2 args: Migrates from 'current' to the topic's defined current version. With 3 args: Migrates from 'current' to 'target' version. Arguments: topic - Keyword identifying the module/component to patch current - Current version string (nil or "0" means start from beginning) target - Target version string (optional, defaults to topic's current version) The function automatically: - Determines upgrade vs downgrade direction - Finds applicable patches between versions - Executes patches in correct order (oldest-first for upgrades, newest-first for downgrades) Example: (apply ::my-app "1.0.0" "2.0.0") ; Upgrade from 1.0.0 to 2.0.0 (apply ::my-app "2.0.0" "1.0.0") ; Downgrade from 2.0.0 to 1.0.0 (apply ::my-app nil) ; Upgrade from beginning to current
available-versionsclj
(available-versions & topics)Returns a map of topics to their current versions.
With no args: Returns all registered topic versions. With args: Returns versions only for specified topics.
Arguments: topics - Zero or more topic keywords to query
Returns: Map of {topic version-string} for registered topics
Example: (available-versions) ; => {:app "2.0.0" :db "1.5.0"} (available-versions :app) ; => {:app "2.0.0"} (available-versions :app :db :unknown) ; => {:app "2.0.0" :db "1.5.0"}
Returns a map of topics to their current versions.
With no args: Returns all registered topic versions.
With args: Returns versions only for specified topics.
Arguments:
topics - Zero or more topic keywords to query
Returns:
Map of {topic version-string} for registered topics
Example:
(available-versions) ; => {:app "2.0.0" :db "1.5.0"}
(available-versions :app) ; => {:app "2.0.0"}
(available-versions :app :db :unknown) ; => {:app "2.0.0" :db "1.5.0"}current-versioncljmacro
(current-version topic & body)Defines the current/target version for a topic.
This version is used as the default target when calling apply with only 2 arguments.
Arguments: topic - Keyword identifying the module/component body - Should return a version string
Example: (current-version ::my-app "2.5.0")
; Can also compute version dynamically (current-version ::my-app (read-version-from-file))
Defines the current/target version for a topic.
This version is used as the default target when calling apply
with only 2 arguments.
Arguments:
topic - Keyword identifying the module/component
body - Should return a version string
Example:
(current-version ::my-app "2.5.0")
; Can also compute version dynamically
(current-version ::my-app
(read-version-from-file))deployed-versioncljmultimethod
downgradecljmacro
(downgrade topic to & body)Defines code to execute when downgrading FROM the specified version.
The body will be executed when applying patches that include this version in the downgrade path. Note: downgrade happens FROM this version to a lower version.
Arguments: topic - Keyword identifying the module/component to - Version string this downgrade migrates FROM body - Code to execute for the downgrade
Example: (downgrade ::database "2.0.0" (drop-column :users :preferences) (restore-legacy-settings))
Defines code to execute when downgrading FROM the specified version.
The body will be executed when applying patches that include this version
in the downgrade path. Note: downgrade happens FROM this version to a
lower version.
Arguments:
topic - Keyword identifying the module/component
to - Version string this downgrade migrates FROM
body - Code to execute for the downgrade
Example:
(downgrade ::database "2.0.0"
(drop-column :users :preferences)
(restore-legacy-settings))previous-versioncljmacro
(previous-version topic & body)Defines the last installed version for a topic.
This version is used when calling apply with only 1 arguments.
Arguments: topic - Keyword identifying the module/component body - Should return a version string
Example: (previous-version ::my-app "2.5.0")
; Can also compute version dynamically (current-version ::my-app (read-version-from-file))
Defines the last installed version for a topic.
This version is used when calling apply
with only 1 arguments.
Arguments:
topic - Keyword identifying the module/component
body - Should return a version string
Example:
(previous-version ::my-app "2.5.0")
; Can also compute version dynamically
(current-version ::my-app
(read-version-from-file))upgradecljmacro
(upgrade topic to & body)Defines code to execute when upgrading TO the specified version.
The body will be executed when applying patches that include this version in the upgrade path.
Arguments: topic - Keyword identifying the module/component to - Version string this upgrade migrates TO body - Code to execute for the upgrade
Example: (upgrade ::database "2.0.0" (add-column :users :preferences :jsonb) (migrate-user-settings))
Defines code to execute when upgrading TO the specified version.
The body will be executed when applying patches that include this version
in the upgrade path.
Arguments:
topic - Keyword identifying the module/component
to - Version string this upgrade migrates TO
body - Code to execute for the upgrade
Example:
(upgrade ::database "2.0.0"
(add-column :users :preferences :jsonb)
(migrate-user-settings))versioncljmultimethod
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