Metadata-Version: 2.1
Name: jsonschema_cn
Version: 0.6
Summary: Compact notation for JSON Schemas
Home-page: http://github.com/fab13n/jsonschema_cn
Author: Fabien Fleutot
Author-email: fleutot@gmail.com
License: BSD
Description: JsonSchema Compact Notation
        ===========================
        
        [Json-schema](https://json-schema.org/understanding-json-schema/reference/)
        is very useful to document and validate inputs and outputs of
        JSON-based REST APIs. Unfortunately, the schemas are more verbose and
        less human-readable than one may wish. This library defines a more
        compact syntax to describe JSON schemas, as well as a parser to
        convert such specifications into actual JSON schema.
        
        At some point in the future, this library may also offer the way back,
        from JSON schemas back to a compact notation.
        
        Informal grammar
        ----------------
        
        Litteral JSON types are accessible as keywords: `boolean`, `string`,
        `integer`, `number`, `null`.
        
        Regular expression strings are represented by `r`-prefixed litteral
        strings, similar to Python litterals: `r"[0-9]+"` converts into
        `{"type": "string", "pattern": "[0-9]+"}`.
        
        Regular expression strings are represented by `f`-prefixed litteral
        strings: `f"uri""` converts into `{"type": "string", "format":
        "uri"}`.
        
        JSON constants are introduced between back-quotes: `` `123` ``
        converts to `{"const": 123}`. If several constants are joined with an
        `|` operator, they are translated into an enum: `` `1`|`2` `` converts
        to `{"enum": [1, 2]}`.
        
        Arrays are described between square brackets:
        
        * `[]` describes every possible array, and can also be written `array`.
        * an homogeneous, non-empty array of integers is denoted `[integer+]`
        * an homogeneous array of integers is denoted `[integer*]`
        * an array of two booleans is denoted `[boolean, boolean]`. It can also
          contain additional items after those two booleans.
        * To prevent items other than those explicitly listed, add an `only`
          keyword at the beginning of the array: `[only boolean, boolean]`.
        * arrays support cardinal suffix between braces: `[]{7}` is an
          array of 7 elements, `[integer*]{3,8}` is an array of between 3 and
          8 integers (inclusive), `[]{_, 9}` an array of at most 9
          elements, `[string*]{4, _}` an array of at least 4 strings.
        * a uniqueness constraint can be added with the `unique` prefix, as in
          `[unique integer+]`, which will allow `[1, 2, 3]` but not `[1, 2, 1]`.
        
        Strings and integers also support cardinal suffixes,
        e.g. `string{16}`, `integer{_, 0xFFFF}`. Integer ranges as well as
        sizes are inclusive.
        
        Objects are described between curly braces:
        
        * `{ }` describes every possible object, and can also be written
          `object`.
        * `{"bar": integer}` is an object with one field `"bar"` of type
          integer, and possibly other fields.
        * Quotes are optional around property names, if they are identifiers other
          than `"_"` or `"only"`: it's legal to write `{bar: integer}`.
        * The wildcard property name `_` gives a type constraint on every
          extra property, e.g.  `{"bar": integer, _: string}` is an object
          with a field `"bar"` of type integer, and optionally other
          properties with any names, but all containing strings.
        * To prevent other fields from being accepted, use a prefix `only`, as in
          `{only "bar": integer}`.
        * To restrict additional property names without completely
          forbidding them, a prefix constraint `only <regex>` can be added,
          e.g. `{only r"[0-9]+" _: integer}` will only accept
          integer-to-integer maps. References to definitions are also
          accepted, as in `{only <int_string>} where int_string = r"[0-9]+"`.
        
        
        Types can be combined:
        
        * With infix operator `&`: `A & B` is the type of objects which
          respect both schemas `A` and `B`.
        * With infix operator `|`: `A | B` is the type of objects which
          respect at least one of the schemas `A` or `B`. `&` takes precedence
          over `|`, i.e. `A & B | C & D` is to be read as `(A&B) | (C&D)`.
        * Parentheses can be added to enforce precedences , e.g. `A & (B|C) & D`
        
        A top-level schema may contain definitions. They are listed after the
        main schema, separated by a `where` keyword from it, and separated
        from each other by `and`. References to definitions must appear
        between angle bracket `<...>`. For instance, `{source: <id>, dest:
        <id>} where id = r"[a-z]+"`.
        
        More formally
        -------------
        
            schema ::= type («where» definitions)?
        
            definitions ::= identifier «=» type («and» identifier «=» type)*
        
            type ::= type «&» type          # allOf those types; takes precedence over «|».
                   | type «|» type          # anyOf those types.
                   | «(» type «)»           # parentheses to enforce precedence.
                   | «not» type             # anything but this type.
                   | «`»json_litteral«`»    # just this JSON constant value.
                   | «<»identifier«>»       # identifier refering to the matching top-level definition.
                   | r"regular_expression"  # String matched by this regex.
                   | f"format"              # json-schema draft7 string format.
                   | «string» cardinal?     # a string, with this cardinal constraint on number of chars.
                   | «integer» cardinal?    # an integer within the range described by cardinal.
                   | «integer» «/» int      # an integer which must be multiple of that int.
                   | «object»               # any object.
                   | «array»                # any array.
                   | «boolean»              # any boolean.
                   | «null»                 # the null value.
                   | «number»               # any number.
                   | object                 # structurally described object.
                   | array                  # structurally described array.
        
            cardinal ::= «{» int «}»        # Exactly that number of chars / items / properties.
                       | «{» «_», int «}»   # At most that number of chars / items / properties.
                       | «{» int, «_» «}»   # At least that number of chars / items / properties.
                       | «{» int, int «}»   # A number of chars / items / properties within this range.
        
        
            object ::= «{» («only» regex?)? (object_key «?»? «:» type «,»...)* «}» cardinal?
                     # if «only» occurs without a regex, no extra property is allowed.
                     # if «only» occurs with a regex, all extra property names must match that regex.
                     # if «?» occurs, the preceding property is optional, otherwise it's required.
        
            object_key ::= identifier    # Litteral property name.
                         | «"»string«"»  # Properties which aren't identifiers must be quoted.
                         | «_»           # Properties not explicitly listed must match the following type.
        
            array ::= «[» «only»? «unique»? (type «,»)* («*»|«+»|ø) «]» cardinal?
                    # if «only» occurs, no extra item is allowed.
                    # if «unique» occurs, each array item must be different from every other.
                    # if «*» occurs, the last type can be repeated from 0 to any times.
                    # Every extra item must be of that type.
                    # if «+» occurs, the last type can be repeated from 1 to any times.
                    # Every extra item must be of that type.
        
            int ::= /0x[0-9a-FA-F]+/ | /[0-9]+/
            identifier ::= /[A-Za-z_][A-Za-z_0-9]*/
        
        
        
        TODO
        ----
        
        Some things that may be added in future versions:
        
        * on objects:
            * limited support for dependent object fields, e.g.
              `{"card_number": integer, "billing_address" if "card_number":
              string, ...}`.
        * on numbers:
            * ranges over floats (reusing cardinal grammar with float
              boundaries)
            * modulus constraints on floats `number/0.25`.
            * exclusive ranges in addition to inclusive ones. May use returned
              braces, e.g. `integer{0,0x100{` as an equivalent for
              `integer{0,0xFF}`?
            * ranges alone are treated as integer ranges, i.e. `{1, 5}` is a
              shortcut for `integer{1, 5}`? Not sure whether it enhances
              readability, and there would be a need for float support in
              ranges then.
        * combine string constraints: regex, format, cardinals...  This can
          already be achieved with operator `&`.
        * add a few `"$comment"` fields for non-obvious translations. Use size
          of notation vs. size of generated schema as a clue, plus the
          presence of such a somment at a higher level in the tree.
        * try to embedded `#`-comments as `"$comment"`? Gather them for each
          `or_sequence` and `'\n'`-join them on top?
        * Implementation:
            * bubble up `?` markers in grammar to the top level.
            * make lazy `jsonschema` property available everywhere.
            * tolerate overlapping definitions as long as overlapping defs
              are equal (relay on lazy `jsonschema` prop + Python dict equality).
        * Syntax sugar:
            * optional marker: `foobar?` is equivalent to `foobar|null`.  Not
              sure whether it's worth it, the difference between a missing
              field and a field holding `null` is most commonly not
              significant.
            * tolerate `"foo"|"bar"` instead of `"foo"` | `"bar"`: bars don't
              appear in JSON constants out of quoted strings.
            * tolerate literal strings as constants, i.e. `"foo"` is
              interpreted as `` `"foo"` ``. Would make the point above
              irrelevant.
            * tolerate chevrons around definitions, i.e `{_: <foo>} where
              <foo> = ...` in addition to `{_: <foo>} where foo = ...`?
            * tolerate literal regexes and references to regexes as object
              keys. references raise issues, as we don't know locally whether
              the reference points to a string, a regex or something else. The
              resulting schema must be checked, at least to refuse references
              to non-regexes, ideally to convert them into regular properties.
            * tolerate `{only <foo>: <bar>}` as a shortcute for `{only <foo>
              _: <bar>}`.
        * better error messages, on incorrect grammars, and on non-validating
          JSON data.
        * reciprocal feature: try and translate a JSON-schema into a shorter
          and more readable JSCN source.
        
        Usage
        -----
        
        From Python:
        
        
        
        ### From command line
        
            $ echo -n '[integer*]' | jscn -
            { "type": "array",
              "items": {"type": "integer"},
              "$schema": "http://json-schema.org/draft-07/schema#"
            }
        
            $ jscn --help
        
            usage: jscn [-h] [-o OUTPUT] [-v] [--version] [filename]
        
            Convert from a compact DSL into full JSON schema.
        
            positional arguments:
              filename              Input file; use '-' to read from stdin.
        
            optional arguments:
              -h, --help            show this help message and exit
              -o OUTPUT, --output OUTPUT
                                    Output file; defaults to stdout
              -v, --verbose         Verbose output
              --version             Display version and exit
        
        ### From Python API
        
        Python's `jsonschema_cn` packaga exports two main constructors:
        
        * `Schema()`, which compiles a source string into a schema object;
        * `Definitions()`, which compiles a source string (a sequence of
          definitions separated by keyword `and`, as in rule `definitions` of
          the formal grammar.
        
        Schema objects have a `jsonschema` property, which contains the Python
        dict of the corresponding JSON schema.
        
        Schemas can be combined with Python operators `&` (`"allOf"`) and `|`
        (`"anyOf"`). When they have definitions, those definition sets are
        merged, and definition names must not overlap.
        
        Schemas can also be combined with definitions through `|`, and
        definitions can be combined together also with `|`.
        
            >>> from jsonschema import Schema, Definitions
        
            >>> defs = Definitions("""
            >>>     id = r"[a-z]+" and
            >>>     byte = integer{0,0xff}
            >>> """)
        
            >>> s = Schema("{only <id>: <byte>}") | defs
            >>> s.jsonschema
            ValueError: Missing definition for byte
        
            >>> s = s | defs
            >>> s.jsonschema
            {"$schema": "http://json-schema.org/draft-07/schema#"
              "type": "object",
              "propertyNames": {"$ref": "#/definitions/id"},
              "additionalProperties": {"$ref": "#/definitions/byte"},
              "definitions": {
                "id":   {"type": "string", "pattern": "[a-z]+"},
                "byte": {"type": "integer", "minimum": 0, "maximum": 255}
              }
            }
        
            >>> Schema("[integer, boolean+]{4}").jsonschema
            { "$schema": "http://json-schema.org/draft-07/schema#",
              "type": "array",
              "minItems": 4, "maxItems": 4,
              "items": [{"type": "integer"}],
              "additionalItems": {"type": "boolean"},
            }
        
        See also
        --------
        
        If you spend a lot of time dealing with complex JSON data structures,
        you might also want to try [jsview](https://github.com/fab13n/jsview),
        a smarter JSON formatter, which tries to effectively use both your
        screen's width and height, by only inserting q carriage returns when
        it makes sense:
        
            $ cat >schema.cn <<EOF
        
            { only codes: [<byte>+], id: r"[a-z]+", issued: f"date"}
            where byte = integer{0, 0xFF}
            EOF
        
            $ jscn schema.cn
        
            {"type": "object", "required": ["codes", "id", "issued"], "properties": {
            "codes": {"type": "array", "items": [{"$ref": "#/definitions/byte"}], "ad
            ditionalItems": {"$ref": "#/definitions/byte"}}, "id": {"type": "string",
            "pattern": "[a-z]+"}, "issued": {"type": "string", "format": "date"}}, "a
            dditionalProperties": false, "definitions": {"byte": {"type": "integer",
            "minimum": 0, "maximum": 255}}, "$schema": "http://json-schema.org/draft-
            07/schema#"}
        
            $ cat schema.cn | jscn - | jsview -
        
            {
              "type": "object",
              "required": ["codes", "id", "issued"],
              "properties": {
                "codes": {
                  "type": "array",
                  "items": [{"$ref": "#/definitions/byte"}],
                  "additionalItems": {"$ref": "#/definitions/byte"}
                },
                "id": {"type": "string", "pattern": "[a-z]+"},
                "issued": {"type": "string", "format": "date"}
              },
              "additionalProperties": false,
              "definitions": {"byte": {"type": "integer", "minimum": 0, "maximum": 255}},
              "$schema": "http://json-schema.org/draft-07/schema#"
            }
        
Keywords: DSL JSON schema jsonschema
Platform: UNKNOWN
Classifier: Development Status :: 3 - Alpha
Classifier: License :: OSI Approved :: BSD License
Classifier: Programming Language :: Python :: 3.6
Classifier: Operating System :: OS Independent
Description-Content-Type: text/markdown
