From cc4a1aed35f5144d809d12166e45c797a6d0e3c6 Mon Sep 17 00:00:00 2001
From: Alexander Schlemmer <alexander@mail-schlemmer.de>
Date: Thu, 17 Mar 2022 14:59:50 +0100
Subject: [PATCH] DOC: updated the index and corrrected the heading levels from
one to two
---
src/doc/high_level_api.org | 121 +++++++++++++++++++++++++++++++++++++
src/doc/index.rst | 1 +
2 files changed, 122 insertions(+)
create mode 100644 src/doc/high_level_api.org
diff --git a/src/doc/high_level_api.org b/src/doc/high_level_api.org
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+++ b/src/doc/high_level_api.org
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+* High Level API
+
+In addition to the old standard pylib API, new versions of pylib ship with a high level API
+that facilitates usage of CaosDB entities within data analysis scripts. In a nutshell that
+API exposes all properties of CaosDB Records as standard python attributes making their
+access easier.
+
+Or to speak it out directly in Python:
+#+BEGIN_SRC python
+
+ import caosdb as db
+ # Old API:
+ r = db.Record()
+ r.add_parent("Experiment")
+ r.add_property(name="alpha", value=5)
+ r.get_property("alpha").value = 25 # setting properties (old api)
+ print(r.get_property("alpha").value + 25) # getting properties (old api)
+
+ from caosdb.high_level_api import convert_to_python_entity
+ obj = convert_to_python_object(r) # create a high level entity
+ obj.r = 25 # setting properties (new api)
+ print(obj.r + 25) # getting properties (new api)
+
+#+END_SRC
+
+
+** Quickstart
+
+The module, needed for the high level API is called:
+caosdb.high_level_api
+
+There are two functions converting entities between the two representation (old API and new API):
+- convert_to_python_object: Convert entities from **old** into **new** representation.
+- convert_to_entity: Convert entities from **new** into **old** representation.
+
+Furthermore there are a few utility functions which expose very practical shorthands:
+- new_high_level_entity: Retrieve a record type and create a new high level entity which contains properties of a certain importance level preset.
+- create_record: Create a new high level entity using the name of a record type and a list of key value pairs as properties.
+- load_external_record: Retrieve a record with a specific name and return it as high level entity.
+- create_entity_container: Convert a high level entity into a standard entity including all sub entities.
+- query: Do a CaosDB query and return the result as a container of high level objects.
+
+So as a first example, you could retrieve any record from CaosDB and use it using its high level representation:
+#+BEGIN_SRC python
+ from caosdb.high_level_api import query
+
+ res = query("FIND Record Experiment")
+ experiment = res[0]
+ # Use a property:
+ print(experiment.date)
+
+ # Use sub properties:
+ print(experiment.output[0].path)
+#+END_SRC
+
+The latter example demonstrates, that the function query is very powerful. For its default parameter
+values it automatically resolves and retrieves references recursively, so that sub properties,
+like the list of output files "output", become immediately available.
+
+**Note** that for the old API you were supposed to run the following series of commands
+to achieve the same result:
+#+BEGIN_SRC python
+ import caosdb as db
+
+ res = db.execute_query("FIND Record Experiment")
+ output = res.get_property("output")
+ output_file = db.File(id=output.value[0].id).retrieve()
+ print(output_file.path)
+#+END_SRC
+
+Resolving subproperties makes use of the "resolve_reference" function provided by the high level
+entity class (CaosDBPythonEntity), with the following parameters:
+- deep: Whether to use recursive retrieval
+- references: Whether to use the supplied db.Container to resolve references. This allows offline usage. Set it to None if you want to automatically retrieve entities from the current CaosDB connection.
+- visited: Needed for recursion, set this to None.
+
+Objects in the high level representation can be serialized to a simple yaml form using the function
+"serialize" with the following parameters:
+- without_metadata: Set this to True if you don't want to see property metadata like "unit" or "importance".
+- visited: Needed for recursion, set this to None.
+
+This function creates a simple dictionary containing a representation of the entity, which can be
+stored to disk and completely deserialized using the function "deserialize".
+
+Furthermore the "__str__" function is overloaded, so that you can use print to directly inspect
+high level objects using the following statement:
+#+BEGIN_SRC python
+print(str(obj))
+#+END_SRC
+
+
+** Concepts
+
+As described in the section [[Quickstart]] the two functions "convert_to_python_object" and "convert_to_entity" convert
+entities beetween the high level and the standard representation.
+
+The high level entities are represented using the following classes from the module caosdb.high_level_api:
+- CaosDBPythonEntity: Base class of the following entity classes.
+- CaosDBPythonRecord
+- CaosDBPythonRecordType
+- CaosDBPythonProperty
+- CaosDBPythonMultiProperty: **WARNING** Not implemented yet.
+- CaosDBPythonFile: Used for file entities and provides an additional "download" function for being able to directly retrieve files from CaosDB.
+
+In addition, there are the following helper structures which are realized as Python data classes:
+- CaosDBPropertyMetaData: For storing meta data about properties.
+- CaosDBPythonUnresolved: The base class of unresolved "things".
+- CaosDBPythonUnresolvedParent: Parents of entities are stored as unresolved parents by default, storing an id or a name of a parent (or both).
+- CaosDBPythonUnresolvedReference: An unresolved reference is a reference property with an id which has not (yet) been resolved to an Entity.
+
+The function "resolve_references" can be used to recursively replace CaosDBPythonUnresolvedReferences into members of type CaosDBPythonRecords
+or CaosDBPythonFile.
+
+Each property stored in a CaosDB record corresponds to:
+- a member attribute of CaosDBPythonRecord **and**
+- an entry in a dict called "metadata" storing a CaosDBPropertyMetadata object with the following information about proeprties:
+ - unit
+ - datatype
+ - description
+ - id
+ - importance
diff --git a/src/doc/index.rst b/src/doc/index.rst
index 004ae3a9..7344b6aa 100644
--- a/src/doc/index.rst
+++ b/src/doc/index.rst
@@ -12,6 +12,7 @@ Welcome to PyCaosDB's documentation!
Concepts <concepts>
Configuration <configuration>
Administration <administration>
+ High Level API <high_level_api>
Code gallery <gallery/index>
API documentation<_apidoc/caosdb>
--
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