jsonb_plpython.c

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#include "postgres.h"

#include "plpy_elog.h"
#include "plpy_typeio.h"
#include "plpython.h"
#include "utils/fmgrprotos.h"
#include "utils/jsonb.h"
#include "utils/numeric.h"

PG_MODULE_MAGIC;

void        _PG_init(void);

/* for PLyObject_AsString in plpy_typeio.c */
typedef char *(*PLyObject_AsString_t) (PyObject *plrv);
static PLyObject_AsString_t PLyObject_AsString_p;

typedef void (*PLy_elog_impl_t) (int elevel, const char *fmt,...);
static PLy_elog_impl_t PLy_elog_impl_p;

/*
 * decimal_constructor is a function from python library and used
 * for transforming strings into python decimal type
 */
static PyObject *decimal_constructor;

static PyObject *PLyObject_FromJsonbContainer(JsonbContainer *jsonb);
static JsonbValue *PLyObject_ToJsonbValue(PyObject *obj,
                                          JsonbParseState **jsonb_state, bool is_elem);

#if PY_MAJOR_VERSION >= 3
typedef PyObject *(*PLyUnicode_FromStringAndSize_t)
            (const char *s, Py_ssize_t size);
static PLyUnicode_FromStringAndSize_t PLyUnicode_FromStringAndSize_p;
#endif

/*
 * Module initialize function: fetch function pointers for cross-module calls.
 */
void
_PG_init(void)
{
    /* Asserts verify that typedefs above match original declarations */
    AssertVariableIsOfType(&PLyObject_AsString, PLyObject_AsString_t);
    PLyObject_AsString_p = (PLyObject_AsString_t)
        load_external_function("$libdir/" PLPYTHON_LIBNAME, "PLyObject_AsString",
                               true, NULL);
#if PY_MAJOR_VERSION >= 3
    AssertVariableIsOfType(&PLyUnicode_FromStringAndSize, PLyUnicode_FromStringAndSize_t);
    PLyUnicode_FromStringAndSize_p = (PLyUnicode_FromStringAndSize_t)
        load_external_function("$libdir/" PLPYTHON_LIBNAME, "PLyUnicode_FromStringAndSize",
                               true, NULL);
#endif

    AssertVariableIsOfType(&PLy_elog_impl, PLy_elog_impl_t);
    PLy_elog_impl_p = (PLy_elog_impl_t)
        load_external_function("$libdir/" PLPYTHON_LIBNAME, "PLy_elog_impl",
                               true, NULL);
}

/* These defines must be after the _PG_init */
#define PLyObject_AsString (PLyObject_AsString_p)
#define PLyUnicode_FromStringAndSize (PLyUnicode_FromStringAndSize_p)
#undef PLy_elog
#define PLy_elog (PLy_elog_impl_p)

/*
 * PLyString_FromJsonbValue
 *
 * Transform string JsonbValue to Python string.
 */
static PyObject *
PLyString_FromJsonbValue(JsonbValue *jbv)
{
    Assert(jbv->type == jbvString);

    return PyString_FromStringAndSize(jbv->val.string.val, jbv->val.string.len);
}

/*
 * PLyString_ToJsonbValue
 *
 * Transform Python string to JsonbValue.
 */
static void
PLyString_ToJsonbValue(PyObject *obj, JsonbValue *jbvElem)
{
    jbvElem->type = jbvString;
    jbvElem->val.string.val = PLyObject_AsString(obj);
    jbvElem->val.string.len = strlen(jbvElem->val.string.val);
}

/*
 * PLyObject_FromJsonbValue
 *
 * Transform JsonbValue to PyObject.
 */
static PyObject *
PLyObject_FromJsonbValue(JsonbValue *jsonbValue)
{
    switch (jsonbValue->type)
    {
        case jbvNull:
            Py_RETURN_NONE;

        case jbvBinary:
            return PLyObject_FromJsonbContainer(jsonbValue->val.binary.data);

        case jbvNumeric:
            {
                Datum       num;
                char       *str;

                num = NumericGetDatum(jsonbValue->val.numeric);
                str = DatumGetCString(DirectFunctionCall1(numeric_out, num));

                return PyObject_CallFunction(decimal_constructor, "s", str);
            }

        case jbvString:
            return PLyString_FromJsonbValue(jsonbValue);

        case jbvBool:
            if (jsonbValue->val.boolean)
                Py_RETURN_TRUE;
            else
                Py_RETURN_FALSE;

        default:
            elog(ERROR, "unexpected jsonb value type: %d", jsonbValue->type);
            return NULL;
    }
}

/*
 * PLyObject_FromJsonbContainer
 *
 * Transform JsonbContainer to PyObject.
 */
static PyObject *
PLyObject_FromJsonbContainer(JsonbContainer *jsonb)
{
    JsonbIteratorToken r;
    JsonbValue  v;
    JsonbIterator *it;
    PyObject   *result;

    it = JsonbIteratorInit(jsonb);
    r = JsonbIteratorNext(&it, &v, true);

    switch (r)
    {
        case WJB_BEGIN_ARRAY:
            if (v.val.array.rawScalar)
            {
                JsonbValue  tmp;

                if ((r = JsonbIteratorNext(&it, &v, true)) != WJB_ELEM ||
                    (r = JsonbIteratorNext(&it, &tmp, true)) != WJB_END_ARRAY ||
                    (r = JsonbIteratorNext(&it, &tmp, true)) != WJB_DONE)
                    elog(ERROR, "unexpected jsonb token: %d", r);

                result = PLyObject_FromJsonbValue(&v);
            }
            else
            {
                PyObject   *volatile elem = NULL;

                result = PyList_New(0);
                if (!result)
                    return NULL;

                PG_TRY();
                {
                    while ((r = JsonbIteratorNext(&it, &v, true)) != WJB_DONE)
                    {
                        if (r != WJB_ELEM)
                            continue;

                        elem = PLyObject_FromJsonbValue(&v);

                        PyList_Append(result, elem);
                        Py_XDECREF(elem);
                        elem = NULL;
                    }
                }
                PG_CATCH();
                {
                    Py_XDECREF(elem);
                    Py_XDECREF(result);
                    PG_RE_THROW();
                }
                PG_END_TRY();
            }
            break;

        case WJB_BEGIN_OBJECT:
            {
                PyObject   *volatile result_v = PyDict_New();
                PyObject   *volatile key = NULL;
                PyObject   *volatile val = NULL;

                if (!result_v)
                    return NULL;

                PG_TRY();
                {
                    while ((r = JsonbIteratorNext(&it, &v, true)) != WJB_DONE)
                    {
                        if (r != WJB_KEY)
                            continue;

                        key = PLyString_FromJsonbValue(&v);
                        if (!key)
                        {
                            Py_XDECREF(result_v);
                            result_v = NULL;
                            break;
                        }

                        if ((r = JsonbIteratorNext(&it, &v, true)) != WJB_VALUE)
                            elog(ERROR, "unexpected jsonb token: %d", r);

                        val = PLyObject_FromJsonbValue(&v);
                        if (!val)
                        {
                            Py_XDECREF(key);
                            key = NULL;
                            Py_XDECREF(result_v);
                            result_v = NULL;
                            break;
                        }

                        PyDict_SetItem(result_v, key, val);

                        Py_XDECREF(key);
                        key = NULL;
                        Py_XDECREF(val);
                        val = NULL;
                    }
                }
                PG_CATCH();
                {
                    Py_XDECREF(result_v);
                    Py_XDECREF(key);
                    Py_XDECREF(val);
                    PG_RE_THROW();
                }
                PG_END_TRY();

                result = result_v;
            }
            break;

        default:
            elog(ERROR, "unexpected jsonb token: %d", r);
            return NULL;
    }

    return result;
}

/*
 * PLyMapping_ToJsonbValue
 *
 * Transform Python dict to JsonbValue.
 */
static JsonbValue *
PLyMapping_ToJsonbValue(PyObject *obj, JsonbParseState **jsonb_state)
{
    Py_ssize_t  pcount;
    PyObject   *volatile items;
    JsonbValue *volatile out;

    pcount = PyMapping_Size(obj);
    items = PyMapping_Items(obj);

    PG_TRY();
    {
        Py_ssize_t  i;

        pushJsonbValue(jsonb_state, WJB_BEGIN_OBJECT, NULL);

        for (i = 0; i < pcount; i++)
        {
            JsonbValue  jbvKey;
            PyObject   *item = PyList_GetItem(items, i);
            PyObject   *key = PyTuple_GetItem(item, 0);
            PyObject   *value = PyTuple_GetItem(item, 1);

            /* Python dictionary can have None as key */
            if (key == Py_None)
            {
                jbvKey.type = jbvString;
                jbvKey.val.string.len = 0;
                jbvKey.val.string.val = "";
            }
            else
            {
                /* All others types of keys we serialize to string */
                PLyString_ToJsonbValue(key, &jbvKey);
            }

            (void) pushJsonbValue(jsonb_state, WJB_KEY, &jbvKey);
            (void) PLyObject_ToJsonbValue(value, jsonb_state, false);
        }

        out = pushJsonbValue(jsonb_state, WJB_END_OBJECT, NULL);
    }
    PG_FINALLY();
    {
        Py_DECREF(items);
    }
    PG_END_TRY();

    return out;
}

/*
 * PLySequence_ToJsonbValue
 *
 * Transform python list to JsonbValue. Expects transformed PyObject and
 * a state required for jsonb construction.
 */
static JsonbValue *
PLySequence_ToJsonbValue(PyObject *obj, JsonbParseState **jsonb_state)
{
    Py_ssize_t  i;
    Py_ssize_t  pcount;
    PyObject   *volatile value = NULL;

    pcount = PySequence_Size(obj);

    pushJsonbValue(jsonb_state, WJB_BEGIN_ARRAY, NULL);

    PG_TRY();
    {
        for (i = 0; i < pcount; i++)
        {
            value = PySequence_GetItem(obj, i);
            Assert(value);

            (void) PLyObject_ToJsonbValue(value, jsonb_state, true);
            Py_XDECREF(value);
            value = NULL;
        }
    }
    PG_CATCH();
    {
        Py_XDECREF(value);
        PG_RE_THROW();
    }
    PG_END_TRY();

    return pushJsonbValue(jsonb_state, WJB_END_ARRAY, NULL);
}

/*
 * PLyNumber_ToJsonbValue(PyObject *obj)
 *
 * Transform python number to JsonbValue.
 */
static JsonbValue *
PLyNumber_ToJsonbValue(PyObject *obj, JsonbValue *jbvNum)
{
    Numeric     num;
    char       *str = PLyObject_AsString(obj);

    PG_TRY();
    {
        Datum       numd;

        numd = DirectFunctionCall3(numeric_in,
                                   CStringGetDatum(str),
                                   ObjectIdGetDatum(InvalidOid),
                                   Int32GetDatum(-1));
        num = DatumGetNumeric(numd);
    }
    PG_CATCH();
    {
        ereport(ERROR,
                (errcode(ERRCODE_DATATYPE_MISMATCH),
                 (errmsg("could not convert value \"%s\" to jsonb", str))));
    }
    PG_END_TRY();

    pfree(str);

    /*
     * jsonb doesn't allow NaN (per JSON specification), so we have to prevent
     * it here explicitly.  (Infinity is also not allowed in jsonb, but
     * numeric_in above already catches that.)
     */
    if (numeric_is_nan(num))
        ereport(ERROR,
                (errcode(ERRCODE_NUMERIC_VALUE_OUT_OF_RANGE),
                 (errmsg("cannot convert NaN to jsonb"))));

    jbvNum->type = jbvNumeric;
    jbvNum->val.numeric = num;

    return jbvNum;
}

/*
 * PLyObject_ToJsonbValue(PyObject *obj)
 *
 * Transform python object to JsonbValue.
 */
static JsonbValue *
PLyObject_ToJsonbValue(PyObject *obj, JsonbParseState **jsonb_state, bool is_elem)
{
    JsonbValue  buf;
    JsonbValue *out;

    if (!(PyString_Check(obj) || PyUnicode_Check(obj)))
    {
        if (PySequence_Check(obj))
            return PLySequence_ToJsonbValue(obj, jsonb_state);
        else if (PyMapping_Check(obj))
            return PLyMapping_ToJsonbValue(obj, jsonb_state);
    }

    /* Allocate JsonbValue in heap only if it is raw scalar value. */
    if (*jsonb_state)
        out = &buf;
    else
        out = palloc(sizeof(JsonbValue));

    if (obj == Py_None)
        out->type = jbvNull;
    else if (PyString_Check(obj) || PyUnicode_Check(obj))
        PLyString_ToJsonbValue(obj, out);

    /*
     * PyNumber_Check() returns true for booleans, so boolean check should
     * come first.
     */
    else if (PyBool_Check(obj))
    {
        out->type = jbvBool;
        out->val.boolean = (obj == Py_True);
    }
    else if (PyNumber_Check(obj))
        out = PLyNumber_ToJsonbValue(obj, out);
    else
        ereport(ERROR,
                (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                 (errmsg("Python type \"%s\" cannot be transformed to jsonb",
                         PLyObject_AsString((PyObject *) obj->ob_type)))));

    /* Push result into 'jsonb_state' unless it is raw scalar value. */
    return (*jsonb_state ?
            pushJsonbValue(jsonb_state, is_elem ? WJB_ELEM : WJB_VALUE, out) :
            out);
}

/*
 * plpython_to_jsonb
 *
 * Transform python object to Jsonb datum
 */
PG_FUNCTION_INFO_V1(plpython_to_jsonb);
Datum
plpython_to_jsonb(PG_FUNCTION_ARGS)
{
    PyObject   *obj;
    JsonbValue *out;
    JsonbParseState *jsonb_state = NULL;

    obj = (PyObject *) PG_GETARG_POINTER(0);
    out = PLyObject_ToJsonbValue(obj, &jsonb_state, true);
    PG_RETURN_POINTER(JsonbValueToJsonb(out));
}

/*
 * jsonb_to_plpython
 *
 * Transform Jsonb datum to PyObject and return it as internal.
 */
PG_FUNCTION_INFO_V1(jsonb_to_plpython);
Datum
jsonb_to_plpython(PG_FUNCTION_ARGS)
{
    PyObject   *result;
    Jsonb      *in = PG_GETARG_JSONB_P(0);

    /*
     * Initialize pointer to Decimal constructor. First we try "cdecimal", C
     * version of decimal library. In case of failure we use slower "decimal"
     * module.
     */
    if (!decimal_constructor)
    {
        PyObject   *decimal_module = PyImport_ImportModule("cdecimal");

        if (!decimal_module)
        {
            PyErr_Clear();
            decimal_module = PyImport_ImportModule("decimal");
        }
        Assert(decimal_module);
        decimal_constructor = PyObject_GetAttrString(decimal_module, "Decimal");
    }

    result = PLyObject_FromJsonbContainer(&in->root);
    if (!result)
        PLy_elog(ERROR, "transformation from jsonb to Python failed");

    return PointerGetDatum(result);
}