lwgeom_out_geojson.c

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#include "../postgis_config.h"
 
/* PostgreSQL headers */
#include "postgres.h"
#include "funcapi.h"
#include "miscadmin.h"
#include "access/htup_details.h"
#include "access/transam.h"
#include "catalog/pg_type.h"
#include "executor/spi.h"
#include "lib/stringinfo.h"
#include "libpq/pqformat.h"
#include "mb/pg_wchar.h"
#include "parser/parse_coerce.h"
#include "utils/array.h"
#include "utils/builtins.h"
#include "utils/date.h"
#include "utils/datetime.h"
#include "utils/lsyscache.h"
#include "utils/json.h"
#if POSTGIS_PGSQL_VERSION < 130
#include "utils/jsonapi.h"
#else
#include "common/jsonapi.h"
#endif
#include "utils/typcache.h"
#include "utils/syscache.h"
 
/* PostGIS headers */
#include "lwgeom_pg.h"
#include "lwgeom_log.h"
#include "liblwgeom.h"
 
 
typedef enum                                    /* type categories for datum_to_json */
{
        JSONTYPE_NULL,                          /* null, so we didn't bother to identify */
        JSONTYPE_BOOL,                          /* boolean (built-in types only) */
        JSONTYPE_NUMERIC,                       /* numeric (ditto) */
        JSONTYPE_DATE,                          /* we use special formatting for datetimes */
        JSONTYPE_TIMESTAMP,
        JSONTYPE_TIMESTAMPTZ,
        JSONTYPE_JSON,                          /* JSON itself (and JSONB) */
        JSONTYPE_ARRAY,                         /* array */
        JSONTYPE_COMPOSITE,                     /* composite */
        JSONTYPE_CAST,                          /* something with an explicit cast to JSON */
        JSONTYPE_OTHER                          /* all else */
} JsonTypeCategory;
 
static void array_dim_to_json(StringInfo result, int dim, int ndims, int *dims,
                                  Datum *vals, bool *nulls, int *valcount,
                                  JsonTypeCategory tcategory, Oid outfuncoid,
                                  bool use_line_feeds);
static void array_to_json_internal(Datum array, StringInfo result,
                                                                   bool use_line_feeds);
static void composite_to_geojson(Datum composite,
                                         char *geom_column_name, int32 maxdecimaldigits,
                                         StringInfo result, bool use_line_feeds,
                                         Oid geom_oid, Oid geog_oid);
static void composite_to_json(Datum composite, StringInfo result,
                                                          bool use_line_feeds);
static void datum_to_json(Datum val, bool is_null, StringInfo result,
                                                  JsonTypeCategory tcategory, Oid outfuncoid,
                                                  bool key_scalar);
static void json_categorize_type(Oid typoid,
                                                                 JsonTypeCategory *tcategory,
                                                                 Oid *outfuncoid);
static char * postgis_JsonEncodeDateTime(char *buf, Datum value, Oid typid);
static int postgis_time2tm(TimeADT time, struct pg_tm *tm, fsec_t *fsec);
static int postgis_timetz2tm(TimeTzADT *time, struct pg_tm *tm, fsec_t *fsec, int *tzp);
 
Datum row_to_geojson(PG_FUNCTION_ARGS);
extern Datum LWGEOM_asGeoJson(PG_FUNCTION_ARGS);
 
/*
 * SQL function row_to_geojson(row)
 */
PG_FUNCTION_INFO_V1(ST_AsGeoJsonRow);
Datum
ST_AsGeoJsonRow(PG_FUNCTION_ARGS)
{
        Datum           array = PG_GETARG_DATUM(0);
        text        *geom_column_text = PG_GETARG_TEXT_P(1);
        int32       maxdecimaldigits = PG_GETARG_INT32(2);
        bool            do_pretty = PG_GETARG_BOOL(3);
        StringInfo      result;
        char        *geom_column = text_to_cstring(geom_column_text);
        Oid geom_oid = InvalidOid;
        Oid geog_oid = InvalidOid;
 
        /* We need to initialize the internal cache to access it later via postgis_oid() */
        postgis_initialize_cache(fcinfo);
        geom_oid = postgis_oid(GEOMETRYOID);
        geog_oid = postgis_oid(GEOGRAPHYOID);
 
        if (strlen(geom_column) == 0)
                geom_column = NULL;
 
        result = makeStringInfo();
 
        composite_to_geojson(array, geom_column, maxdecimaldigits, result, do_pretty, geom_oid, geog_oid);
 
        PG_RETURN_TEXT_P(cstring_to_text_with_len(result->data, result->len));
}
 
/*
 * Turn a composite / record into GEOJSON.
 */
static void
composite_to_geojson(Datum composite, char *geom_column_name, int32 maxdecimaldigits,
                                         StringInfo result, bool use_line_feeds, Oid geom_oid, Oid geog_oid)
{
        HeapTupleHeader td;
        Oid                     tupType;
        int32           tupTypmod;
        TupleDesc       tupdesc;
        HeapTupleData tmptup,
                           *tuple;
        int                     i;
        bool            needsep = false;
        const char *sep;
        StringInfo      props = makeStringInfo();
        bool            geom_column_found = false;
 
        sep = use_line_feeds ? ",\n " : ", ";
 
        td = DatumGetHeapTupleHeader(composite);
 
        /* Extract rowtype info and find a tupdesc */
        tupType = HeapTupleHeaderGetTypeId(td);
        tupTypmod = HeapTupleHeaderGetTypMod(td);
        tupdesc = lookup_rowtype_tupdesc(tupType, tupTypmod);
 
        /* Build a temporary HeapTuple control structure */
        tmptup.t_len = HeapTupleHeaderGetDatumLength(td);
        tmptup.t_data = td;
        tuple = &tmptup;
 
        appendStringInfoString(result, "{\"type\": \"Feature\", \"geometry\": ");
 
        for (i = 0; i < tupdesc->natts; i++)
        {
                Datum           val;
                bool            isnull;
                char       *attname;
                JsonTypeCategory tcategory;
                Oid                     outfuncoid;
                Form_pg_attribute att = TupleDescAttr(tupdesc, i);
                bool        is_geom_column = false;
 
                if (att->attisdropped)
                        continue;
 
                attname = NameStr(att->attname);
                /* Use the column name if provided, use the first geometry column otherwise */
                if (geom_column_name)
                        is_geom_column = (strcmp(attname, geom_column_name) == 0);
                else
                        is_geom_column = (att->atttypid == geom_oid || att->atttypid == geog_oid);
 
                if ((!geom_column_found) && is_geom_column)
                {
                        /* this is our geom column */
                        geom_column_found = true;
 
                        val = heap_getattr(tuple, i + 1, tupdesc, &isnull);
                        if (!isnull)
                        {
                                appendStringInfo(result, "%s",
                                        TextDatumGetCString(DirectFunctionCall2(LWGEOM_asGeoJson, val, Int32GetDatum(maxdecimaldigits))));
                        }
                        else
                        {
                                appendStringInfoString(result, "{\"type\": null}");
                        }
                }
                else
                {
                        if (needsep)
                                appendStringInfoString(props, sep);
                        needsep = true;
 
                        escape_json(props, attname);
                        appendStringInfoString(props, ": ");
 
                        val = heap_getattr(tuple, i + 1, tupdesc, &isnull);
 
                        if (isnull)
                        {
                                tcategory = JSONTYPE_NULL;
                                outfuncoid = InvalidOid;
                        }
                        else
                                json_categorize_type(att->atttypid, &tcategory, &outfuncoid);
 
                        datum_to_json(val, isnull, props, tcategory, outfuncoid, false);
                }
        }
 
        if (!geom_column_found)
                ereport(ERROR,
                                (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
                                 errmsg("geometry column is missing")));
 
        appendStringInfoString(result, ", \"properties\": {");
        appendStringInfo(result, "%s", props->data);
 
        appendStringInfoString(result, "}}");
        ReleaseTupleDesc(tupdesc);
}
 
/*
 * The following code was all cut and pasted directly from
 * json.c from the Postgres source tree as of 2019-03-28.
 * It would be far better if these were exported from the
 * backend so we could just use them here. Maybe someday.
 */
 
/*
 * Determine how we want to print values of a given type in datum_to_json.
 *
 * Given the datatype OID, return its JsonTypeCategory, as well as the type's
 * output function OID.  If the returned category is JSONTYPE_CAST, we
 * return the OID of the type->JSON cast function instead.
 */
static void
json_categorize_type(Oid typoid,
                                         JsonTypeCategory *tcategory,
                                         Oid *outfuncoid)
{
        bool            typisvarlena;
 
        /* Look through any domain */
        typoid = getBaseType(typoid);
 
        *outfuncoid = InvalidOid;
 
        /*
         * We need to get the output function for everything except date and
         * timestamp types, array and composite types, booleans, and non-builtin
         * types where there's a cast to json.
         */
 
        switch (typoid)
        {
                case BOOLOID:
                        *tcategory = JSONTYPE_BOOL;
                        break;
 
                case INT2OID:
                case INT4OID:
                case INT8OID:
                case FLOAT4OID:
                case FLOAT8OID:
                case NUMERICOID:
                        getTypeOutputInfo(typoid, outfuncoid, &typisvarlena);
                        *tcategory = JSONTYPE_NUMERIC;
                        break;
 
                case DATEOID:
                        *tcategory = JSONTYPE_DATE;
                        break;
 
                case TIMESTAMPOID:
                        *tcategory = JSONTYPE_TIMESTAMP;
                        break;
 
                case TIMESTAMPTZOID:
                        *tcategory = JSONTYPE_TIMESTAMPTZ;
                        break;
 
                case JSONOID:
                case JSONBOID:
                        getTypeOutputInfo(typoid, outfuncoid, &typisvarlena);
                        *tcategory = JSONTYPE_JSON;
                        break;
 
                default:
                        /* Check for arrays and composites */
                        if (OidIsValid(get_element_type(typoid)) || typoid == ANYARRAYOID
                                || typoid == RECORDARRAYOID)
                                *tcategory = JSONTYPE_ARRAY;
                        else if (type_is_rowtype(typoid))       /* includes RECORDOID */
                                *tcategory = JSONTYPE_COMPOSITE;
                        else
                        {
                                /* It's probably the general case ... */
                                *tcategory = JSONTYPE_OTHER;
                                /* but let's look for a cast to json, if it's not built-in */
                                if (typoid >= FirstNormalObjectId)
                                {
                                        Oid                     castfunc;
                                        CoercionPathType ctype;
 
                                        ctype = find_coercion_pathway(JSONOID, typoid,
                                                                                                  COERCION_EXPLICIT,
                                                                                                  &castfunc);
                                        if (ctype == COERCION_PATH_FUNC && OidIsValid(castfunc))
                                        {
                                                *tcategory = JSONTYPE_CAST;
                                                *outfuncoid = castfunc;
                                        }
                                        else
                                        {
                                                /* non builtin type with no cast */
                                                getTypeOutputInfo(typoid, outfuncoid, &typisvarlena);
                                        }
                                }
                                else
                                {
                                        /* any other builtin type */
                                        getTypeOutputInfo(typoid, outfuncoid, &typisvarlena);
                                }
                        }
                        break;
        }
}
 
/*
 * Turn a Datum into JSON text, appending the string to "result".
 *
 * tcategory and outfuncoid are from a previous call to json_categorize_type,
 * except that if is_null is true then they can be invalid.
 *
 * If key_scalar is true, the value is being printed as a key, so insist
 * it's of an acceptable type, and force it to be quoted.
 */
static void
datum_to_json(Datum val, bool is_null, StringInfo result,
                          JsonTypeCategory tcategory, Oid outfuncoid,
                          bool key_scalar)
{
        char       *outputstr;
        text       *jsontext;
 
        check_stack_depth();
 
        /* callers are expected to ensure that null keys are not passed in */
        Assert(!(key_scalar && is_null));
 
        if (is_null)
        {
                appendStringInfoString(result, "null");
                return;
        }
 
        if (key_scalar &&
                (tcategory == JSONTYPE_ARRAY ||
                 tcategory == JSONTYPE_COMPOSITE ||
                 tcategory == JSONTYPE_JSON ||
                 tcategory == JSONTYPE_CAST))
                ereport(ERROR,
                                (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
                                 errmsg("key value must be scalar, not array, composite, or json")));
 
        switch (tcategory)
        {
                case JSONTYPE_ARRAY:
                        array_to_json_internal(val, result, false);
                        break;
                case JSONTYPE_COMPOSITE:
                        composite_to_json(val, result, false);
                        break;
                case JSONTYPE_BOOL:
                        outputstr = DatumGetBool(val) ? "true" : "false";
                        if (key_scalar)
                                escape_json(result, outputstr);
                        else
                                appendStringInfoString(result, outputstr);
                        break;
                case JSONTYPE_NUMERIC:
                        outputstr = OidOutputFunctionCall(outfuncoid, val);
 
                        /*
                         * Don't call escape_json for a non-key if it's a valid JSON
                         * number.
                         */
                        if (!key_scalar && IsValidJsonNumber(outputstr, strlen(outputstr)))
                                appendStringInfoString(result, outputstr);
                        else
                                escape_json(result, outputstr);
                        pfree(outputstr);
                        break;
                case JSONTYPE_DATE:
                        {
                                char            buf[MAXDATELEN + 1];
 
                                postgis_JsonEncodeDateTime(buf, val, DATEOID);
                                appendStringInfo(result, "\"%s\"", buf);
                        }
                        break;
                case JSONTYPE_TIMESTAMP:
                        {
                                char            buf[MAXDATELEN + 1];
 
                                postgis_JsonEncodeDateTime(buf, val, TIMESTAMPOID);
                                appendStringInfo(result, "\"%s\"", buf);
                        }
                        break;
                case JSONTYPE_TIMESTAMPTZ:
                        {
                                char            buf[MAXDATELEN + 1];
 
                                postgis_JsonEncodeDateTime(buf, val, TIMESTAMPTZOID);
                                appendStringInfo(result, "\"%s\"", buf);
                        }
                        break;
                case JSONTYPE_JSON:
                        /* JSON and JSONB output will already be escaped */
                        outputstr = OidOutputFunctionCall(outfuncoid, val);
                        appendStringInfoString(result, outputstr);
                        pfree(outputstr);
                        break;
                case JSONTYPE_CAST:
                        /* outfuncoid refers to a cast function, not an output function */
                        jsontext = DatumGetTextPP(OidFunctionCall1(outfuncoid, val));
                        outputstr = text_to_cstring(jsontext);
                        appendStringInfoString(result, outputstr);
                        pfree(outputstr);
                        pfree(jsontext);
                        break;
                default:
                        outputstr = OidOutputFunctionCall(outfuncoid, val);
                        escape_json(result, outputstr);
                        pfree(outputstr);
                        break;
        }
}
 
/*
 * Turn an array into JSON.
 */
static void
array_to_json_internal(Datum array, StringInfo result, bool use_line_feeds)
{
        ArrayType  *v = DatumGetArrayTypeP(array);
        Oid                     element_type = ARR_ELEMTYPE(v);
        int                *dim;
        int                     ndim;
        int                     nitems;
        int                     count = 0;
        Datum      *elements;
        bool       *nulls;
        int16           typlen;
        bool            typbyval;
        char            typalign;
        JsonTypeCategory tcategory;
        Oid                     outfuncoid;
 
        ndim = ARR_NDIM(v);
        dim = ARR_DIMS(v);
        nitems = ArrayGetNItems(ndim, dim);
 
        if (nitems <= 0)
        {
                appendStringInfoString(result, "[]");
                return;
        }
 
        get_typlenbyvalalign(element_type,
                                                 &typlen, &typbyval, &typalign);
 
        json_categorize_type(element_type,
                                                 &tcategory, &outfuncoid);
 
        deconstruct_array(v, element_type, typlen, typbyval,
                                          typalign, &elements, &nulls,
                                          &nitems);
 
        array_dim_to_json(result, 0, ndim, dim, elements, nulls, &count, tcategory,
                                          outfuncoid, use_line_feeds);
 
        pfree(elements);
        pfree(nulls);
}
 
/*
 * Turn a composite / record into JSON.
 */
static void
composite_to_json(Datum composite, StringInfo result, bool use_line_feeds)
{
        HeapTupleHeader td;
        Oid                     tupType;
        int32           tupTypmod;
        TupleDesc       tupdesc;
        HeapTupleData tmptup,
                           *tuple;
        int                     i;
        bool            needsep = false;
        const char *sep;
 
        sep = use_line_feeds ? ",\n " : ",";
 
        td = DatumGetHeapTupleHeader(composite);
 
        /* Extract rowtype info and find a tupdesc */
        tupType = HeapTupleHeaderGetTypeId(td);
        tupTypmod = HeapTupleHeaderGetTypMod(td);
        tupdesc = lookup_rowtype_tupdesc(tupType, tupTypmod);
 
        /* Build a temporary HeapTuple control structure */
        tmptup.t_len = HeapTupleHeaderGetDatumLength(td);
        tmptup.t_data = td;
        tuple = &tmptup;
 
        appendStringInfoChar(result, '{');
 
        for (i = 0; i < tupdesc->natts; i++)
        {
                Datum           val;
                bool            isnull;
                char       *attname;
                JsonTypeCategory tcategory;
                Oid                     outfuncoid;
                Form_pg_attribute att = TupleDescAttr(tupdesc, i);
 
                if (att->attisdropped)
                        continue;
 
                if (needsep)
                        appendStringInfoString(result, sep);
                needsep = true;
 
                attname = NameStr(att->attname);
                escape_json(result, attname);
                appendStringInfoChar(result, ':');
 
                val = heap_getattr(tuple, i + 1, tupdesc, &isnull);
 
                if (isnull)
                {
                        tcategory = JSONTYPE_NULL;
                        outfuncoid = InvalidOid;
                }
                else
                        json_categorize_type(att->atttypid, &tcategory, &outfuncoid);
 
                datum_to_json(val, isnull, result, tcategory, outfuncoid, false);
        }
 
        appendStringInfoChar(result, '}');
        ReleaseTupleDesc(tupdesc);
}
 
/*
 * Process a single dimension of an array.
 * If it's the innermost dimension, output the values, otherwise call
 * ourselves recursively to process the next dimension.
 */
static void
array_dim_to_json(StringInfo result, int dim, int ndims, int *dims, Datum *vals,
                                  bool *nulls, int *valcount, JsonTypeCategory tcategory,
                                  Oid outfuncoid, bool use_line_feeds)
{
        int                     i;
        const char *sep;
 
        Assert(dim < ndims);
 
        sep = use_line_feeds ? ",\n " : ",";
 
        appendStringInfoChar(result, '[');
 
        for (i = 1; i <= dims[dim]; i++)
        {
                if (i > 1)
                        appendStringInfoString(result, sep);
 
                if (dim + 1 == ndims)
                {
                        datum_to_json(vals[*valcount], nulls[*valcount], result, tcategory,
                                                  outfuncoid, false);
                        (*valcount)++;
                }
                else
                {
                        /*
                         * Do we want line feeds on inner dimensions of arrays? For now
                         * we'll say no.
                         */
                        array_dim_to_json(result, dim + 1, ndims, dims, vals, nulls,
                                                          valcount, tcategory, outfuncoid, false);
                }
        }
 
        appendStringInfoChar(result, ']');
}
 
static int
postgis_time2tm(TimeADT time, struct pg_tm *tm, fsec_t *fsec)
{
        tm->tm_hour = time / USECS_PER_HOUR;
        time -= tm->tm_hour * USECS_PER_HOUR;
        tm->tm_min = time / USECS_PER_MINUTE;
        time -= tm->tm_min * USECS_PER_MINUTE;
        tm->tm_sec = time / USECS_PER_SEC;
        time -= tm->tm_sec * USECS_PER_SEC;
        *fsec = time;
        return 0;
}
 
static int
postgis_timetz2tm(TimeTzADT *time, struct pg_tm *tm, fsec_t *fsec, int *tzp)
{
        TimeOffset      trem = time->time;
 
        tm->tm_hour = trem / USECS_PER_HOUR;
        trem -= tm->tm_hour * USECS_PER_HOUR;
        tm->tm_min = trem / USECS_PER_MINUTE;
        trem -= tm->tm_min * USECS_PER_MINUTE;
        tm->tm_sec = trem / USECS_PER_SEC;
        *fsec = trem - tm->tm_sec * USECS_PER_SEC;
 
        if (tzp != NULL)
                *tzp = time->zone;
 
        return 0;
}
 
static char *
postgis_JsonEncodeDateTime(char *buf, Datum value, Oid typid)
{
        if (!buf)
                buf = palloc(MAXDATELEN + 1);
 
        switch (typid)
        {
                case DATEOID:
                        {
                                DateADT         date;
                                struct pg_tm tm;
 
                                date = DatumGetDateADT(value);
 
                                /* Same as date_out(), but forcing DateStyle */
                                if (DATE_NOT_FINITE(date))
                                        EncodeSpecialDate(date, buf);
                                else
                                {
                                        j2date(date + POSTGRES_EPOCH_JDATE,
                                                   &(tm.tm_year), &(tm.tm_mon), &(tm.tm_mday));
                                        EncodeDateOnly(&tm, USE_XSD_DATES, buf);
                                }
                        }
                        break;
                case TIMEOID:
                        {
                                TimeADT         time = DatumGetTimeADT(value);
                                struct pg_tm tt,
                                                   *tm = &tt;
                                fsec_t          fsec;
 
                                /* Same as time_out(), but forcing DateStyle */
                                postgis_time2tm(time, tm, &fsec);
                                EncodeTimeOnly(tm, fsec, false, 0, USE_XSD_DATES, buf);
                        }
                        break;
                case TIMETZOID:
                        {
                                TimeTzADT  *time = DatumGetTimeTzADTP(value);
                                struct pg_tm tt,
                                                   *tm = &tt;
                                fsec_t          fsec;
                                int                     tz;
 
                                /* Same as timetz_out(), but forcing DateStyle */
                                postgis_timetz2tm(time, tm, &fsec, &tz);
                                EncodeTimeOnly(tm, fsec, true, tz, USE_XSD_DATES, buf);
                        }
                        break;
                case TIMESTAMPOID:
                        {
                                Timestamp       timestamp;
                                struct pg_tm tm;
                                fsec_t          fsec;
 
                                timestamp = DatumGetTimestamp(value);
                                /* Same as timestamp_out(), but forcing DateStyle */
                                if (TIMESTAMP_NOT_FINITE(timestamp))
                                        EncodeSpecialTimestamp(timestamp, buf);
                                else if (timestamp2tm(timestamp, NULL, &tm, &fsec, NULL, NULL) == 0)
                                        EncodeDateTime(&tm, fsec, false, 0, NULL, USE_XSD_DATES, buf);
                                else
                                        ereport(ERROR,
                                                        (errcode(ERRCODE_DATETIME_VALUE_OUT_OF_RANGE),
                                                         errmsg("timestamp out of range")));
                        }
                        break;
                case TIMESTAMPTZOID:
                        {
                                TimestampTz timestamp;
                                struct pg_tm tm;
                                int                     tz;
                                fsec_t          fsec;
                                const char *tzn = NULL;
 
                                timestamp = DatumGetTimestampTz(value);
                                /* Same as timestamptz_out(), but forcing DateStyle */
                                if (TIMESTAMP_NOT_FINITE(timestamp))
                                        EncodeSpecialTimestamp(timestamp, buf);
                                else if (timestamp2tm(timestamp, &tz, &tm, &fsec, &tzn, NULL) == 0)
                                        EncodeDateTime(&tm, fsec, true, tz, tzn, USE_XSD_DATES, buf);
                                else
                                        ereport(ERROR,
                                                        (errcode(ERRCODE_DATETIME_VALUE_OUT_OF_RANGE),
                                                         errmsg("timestamp out of range")));
                        }
                        break;
                default:
                        elog(ERROR, "unknown jsonb value datetime type oid %d", typid);
                        return NULL;
        }
 
        return buf;
}