composite_to_geojson()

static void composite_to_geojson ( FunctionCallInfo  fcinfo, Datum  composite, char *  geom_column_name, char *  id_column_name, int32  maxdecimaldigits, StringInfo  result, bool  use_line_feeds, Oid  geom_oid, Oid  geog_oid  )

static

Definition at line 130 of file lwgeom_out_geojson.c.

{
        HeapTupleHeader td;
        Oid tupType;
        int32 tupTypmod;
        TupleDesc tupdesc;
        HeapTupleData tmptup, *tuple;
        int i;
        bool needsep = false;
        const char *sep;
        StringInfo props = makeStringInfo();
        StringInfo id = makeStringInfo();
        bool geom_column_found = false;
        bool id_column_found = false;
        HTAB *prop_keys = NULL;
        HASHCTL ctl;
 
        MemSet(&ctl, 0, sizeof(ctl));
        ctl.keysize = NAMEDATALEN;
        ctl.entrysize = sizeof(GeoJsonPropKey);
        ctl.hcxt = CurrentMemoryContext;
 
        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);
 
        /*
         * Keep track of property names for this feature so that we can warn
         * when SQL supplies duplicate aliases.  GeoJSON accepts repeated keys,
         * yet downstream PostgreSQL jsonb casts retain only the last value, so
         * surfacing the issue here prevents silent information loss.
         */
        prop_keys =
#if POSTGIS_PGSQL_VERSION <= 130
            hash_create("GeoJSON property keys", Max(tupdesc->natts, 8), &ctl, HASH_ELEM | HASH_CONTEXT);
#else
            hash_create("GeoJSON property keys", Max(tupdesc->natts, 8), &ctl, HASH_ELEM | HASH_CONTEXT | HASH_STRINGS);
#endif
 
        /* 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;
                bool is_id_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 (id_column_name)
                        is_id_column = (strcmp(attname, id_column_name) == 0);
 
                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(CallerFInfoFunctionCall2(LWGEOM_asGeoJson,
                                                                                 fcinfo->flinfo,
                                                                                 InvalidOid,
                                                                                 val,
                                                                                 Int32GetDatum(maxdecimaldigits))));
                        }
                        else
                        {
                                appendStringInfoString(result, "null");
                        }
                }
                else if (is_id_column)
                {
                        id_column_found = true;
 
                        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, id, tcategory, outfuncoid, false);
                }
                else
                {
                        bool found;
 
                        if (needsep)
                                appendStringInfoString(props, sep);
                        needsep = true;
 
                        (void)hash_search(prop_keys, attname, HASH_ENTER, &found);
                        if (found)
                        {
                                ereport(
                                    WARNING,
                                    (errmsg("duplicate key \"%s\" encountered while building GeoJSON properties",
                                            attname),
                                     errhint("Only the last value for each key is preserved when casting to JSONB.")));
                        }
 
                        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")));
 
        if (id_column_name)
        {
                if (!id_column_found)
                        ereport(ERROR,
                                (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
                                 errmsg("Specified id column \"%s\" is missing", id_column_name)));
 
                appendStringInfoString(result, ", \"id\": ");
                appendStringInfo(result, "%s", id->data);
        }
 
        appendStringInfoString(result, ", \"properties\": {");
        appendStringInfo(result, "%s", props->data);
 
        appendStringInfoString(result, "}}");
        hash_destroy(prop_keys);
        ReleaseTupleDesc(tupdesc);
}

References datum_to_json(), json_categorize_type(), JSONTYPE_NULL, LWGEOM_asGeoJson(), and result.

Referenced by ST_AsGeoJsonRow().

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