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PG: serialize GDAL multidomain metadata of layer as XML in a ogr_syst…
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…em_tables.metadata table
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@rouault
rouault committed Dec 13, 2023
1 parent d26bb28 commit b00e954
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Showing 3 changed files with 255 additions and 3 deletions.
37 changes: 37 additions & 0 deletions autotest/ogr/ogr_pg.py
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Original file line number Diff line number Diff line change
Expand Up @@ -4904,6 +4904,43 @@ def test_ogr_pg_84(pg_ds):
assert lyr.GetMetadataItem("DESCRIPTION") is None


###############################################################################
# Test metadata


@only_without_postgis
def test_ogr_pg_metadata(pg_ds):

pg_ds = reconnect(pg_ds, update=1)
lyr = pg_ds.CreateLayer(
"test_ogr_pg_metadata", geom_type=ogr.wkbPoint, options=["OVERWRITE=YES"]
)
lyr.SetMetadata({"foo": "bar"})
lyr.SetMetadataItem("bar", "baz")
lyr.SetMetadataItem("DESCRIPTION", "my_desc")

pg_ds = reconnect(pg_ds, update=1)
with pg_ds.ExecuteSQL(
"SELECT * FROM ogr_system_tables.metadata WHERE table_name = 'test_ogr_pg_metadata'"
) as sql_lyr:
assert sql_lyr.GetFeatureCount() == 1
lyr = pg_ds.GetLayerByName("test_ogr_pg_metadata")
assert lyr.GetMetadata_Dict() == {
"DESCRIPTION": "my_desc",
"foo": "bar",
"bar": "baz",
}
lyr.SetMetadata(None)

pg_ds = reconnect(pg_ds, update=1)
with pg_ds.ExecuteSQL(
"SELECT * FROM ogr_system_tables.metadata WHERE table_name = 'test_ogr_pg_metadata'"
) as sql_lyr:
assert sql_lyr.GetFeatureCount() == 0
lyr = pg_ds.GetLayerByName("test_ogr_pg_metadata")
assert lyr.GetMetadata_Dict() == {}


###############################################################################
# Test append of several layers in PG_USE_COPY mode (#6411)

Expand Down
5 changes: 5 additions & 0 deletions ogr/ogrsf_frmts/pg/ogr_pg.h
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Original file line number Diff line number Diff line change
Expand Up @@ -300,6 +300,8 @@ class OGRPGTableLayer final : public OGRPGLayer
char *pszSchemaName = nullptr;
char *m_pszTableDescription = nullptr;
CPLString osForcedDescription{};
bool m_bMetadataLoaded = false;
bool m_bMetadataModified = false;
char *pszSqlTableName = nullptr;
int bTableDefinitionValid = -1;

Expand Down Expand Up @@ -367,6 +369,9 @@ class OGRPGTableLayer final : public OGRPGLayer

void UpdateSequenceIfNeeded();

void LoadMetadata();
void SerializeMetadata();

public:
OGRPGTableLayer(OGRPGDataSource *, CPLString &osCurrentSchema,
const char *pszTableName, const char *pszSchemaName,
Expand Down
216 changes: 213 additions & 3 deletions ogr/ogrsf_frmts/pg/ogrpgtablelayer.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -221,6 +221,7 @@ OGRPGTableLayer::~OGRPGTableLayer()
if (bCopyActive)
EndCopy();
UpdateSequenceIfNeeded();
SerializeMetadata();

CPLFree(pszSqlTableName);
CPLFree(pszTableName);
Expand All @@ -231,12 +232,207 @@ OGRPGTableLayer::~OGRPGTableLayer()
CSLDestroy(papszOverrideColumnTypes);
}

/************************************************************************/
/* LoadMetadata() */
/************************************************************************/

void OGRPGTableLayer::LoadMetadata()
{
if (m_bMetadataLoaded)
return;
m_bMetadataLoaded = true;

PGconn *hPGConn = poDS->GetPGConn();
const std::string osSQL(
CPLSPrintf("SELECT metadata FROM ogr_system_tables.metadata WHERE "
"schema_name = %s AND table_name = %s",
OGRPGEscapeString(hPGConn, pszSchemaName).c_str(),
OGRPGEscapeString(hPGConn, pszTableName).c_str()));
CPLErrorHandlerPusher oErrorHandler(CPLQuietErrorHandler);
CPLErrorStateBackuper oBackuper;
auto poSqlLyr = poDS->ExecuteSQL(osSQL.c_str(), nullptr, nullptr);
if (poSqlLyr)
{
auto poFeature =
std::unique_ptr<OGRFeature>(poSqlLyr->GetNextFeature());
if (poFeature)
{
if (poFeature->IsFieldSetAndNotNull(0))
{
const char *pszXML = poFeature->GetFieldAsString(0);
if (pszXML)
{
auto psRoot = CPLParseXMLString(pszXML);
if (psRoot)
{
oMDMD.XMLInit(psRoot, true);
CPLDestroyXMLNode(psRoot);
}
}
}
}
poDS->ReleaseResultSet(poSqlLyr);
}
}

/************************************************************************/
/* SerializeMetadata() */
/************************************************************************/

void OGRPGTableLayer::SerializeMetadata()
{
if (!m_bMetadataModified)
return;

PGconn *hPGConn = poDS->GetPGConn();
CPLXMLNode *psMD = oMDMD.Serialize();

if (psMD)
{
// Remove DESCRIPTION and OLMD_FID64 items from metadata

CPLXMLNode *psPrev = nullptr;
for (CPLXMLNode *psIter = psMD; psIter;)
{
CPLXMLNode *psNext = psIter->psNext;
if (psIter->eType == CXT_Element &&
strcmp(psIter->pszValue, "Metadata") == 0 &&
CPLGetXMLNode(psIter, "domain") == nullptr)
{
bool bFoundInterestingItems = false;
for (CPLXMLNode *psIter2 = psIter->psChild; psIter2;)
{
CPLXMLNode *psNext2 = psIter2->psNext;
if (psIter2->eType == CXT_Element &&
strcmp(psIter2->pszValue, "MDI") == 0 &&
(EQUAL(CPLGetXMLValue(psIter2, "key", ""),
OLMD_FID64) ||
EQUAL(CPLGetXMLValue(psIter2, "key", ""),
"DESCRIPTION")))
{
CPLRemoveXMLChild(psIter, psIter2);
}
else
{
bFoundInterestingItems = true;
}
psIter2 = psNext2;
}
if (!bFoundInterestingItems)
{
if (psPrev)
psPrev->psNext = psNext;
else
psMD = psNext;
psIter->psNext = nullptr;
CPLDestroyXMLNode(psIter);
}
}
psIter = psNext;
psPrev = psIter;
}
}

if (psMD)
{
PGresult *hResult = OGRPG_PQexec(
hPGConn, "CREATE SCHEMA IF NOT EXISTS ogr_system_tables");
OGRPGClearResult(hResult);

hResult = OGRPG_PQexec(
hPGConn, "CREATE TABLE IF NOT EXISTS ogr_system_tables.metadata("
"id SERIAL, "
"schema_name TEXT NOT NULL, "
"table_name TEXT NOT NULL, "
"metadata TEXT,"
"UNIQUE(schema_name, table_name))");
OGRPGClearResult(hResult);

hResult = OGRPG_PQexec(
hPGConn,
"DROP FUNCTION IF EXISTS "
"ogr_system_tables.event_trigger_function_for_metadata CASCADE");
OGRPGClearResult(hResult);

hResult = OGRPG_PQexec(
hPGConn,
"CREATE FUNCTION "
"ogr_system_tables.event_trigger_function_for_metadata()\n"
"RETURNS event_trigger LANGUAGE plpgsql AS $$\n"
"DECLARE\n"
" obj record;\n"
"BEGIN\n"
" FOR obj IN SELECT * FROM pg_event_trigger_dropped_objects()\n"
" LOOP\n"
" IF obj.object_type = 'table' THEN\n"
" DELETE FROM ogr_system_tables.metadata m WHERE "
"m.schema_name = obj.schema_name AND m.table_name = "
"obj.object_name;\n"
" END IF;\n"
" END LOOP;\n"
"END;\n"
"$$;");
OGRPGClearResult(hResult);

hResult = OGRPG_PQexec(hPGConn,
"DROP EVENT TRIGGER IF EXISTS "
"ogr_system_tables_event_trigger_for_metadata");
OGRPGClearResult(hResult);

hResult = OGRPG_PQexec(
hPGConn,
"CREATE EVENT TRIGGER ogr_system_tables_event_trigger_for_metadata "
"ON sql_drop "
"EXECUTE FUNCTION "
"ogr_system_tables.event_trigger_function_for_metadata()");
OGRPGClearResult(hResult);

CPLString osCommand;
osCommand.Printf("DELETE FROM ogr_system_tables.metadata WHERE "
"schema_name = %s AND table_name = %s",
OGRPGEscapeString(hPGConn, pszSchemaName).c_str(),
OGRPGEscapeString(hPGConn, pszTableName).c_str());
hResult = OGRPG_PQexec(hPGConn, osCommand.c_str());
OGRPGClearResult(hResult);

CPLXMLNode *psRoot =
CPLCreateXMLNode(nullptr, CXT_Element, "GDALMetadata");
CPLAddXMLChild(psRoot, psMD);
char *pszXML = CPLSerializeXMLTree(psRoot);
// CPLDebug("PG", "Serializing %s", pszXML);

osCommand.Printf("INSERT INTO ogr_system_tables.metadata (schema_name, "
"table_name, metadata) VALUES (%s, %s, %s)",
OGRPGEscapeString(hPGConn, pszSchemaName).c_str(),
OGRPGEscapeString(hPGConn, pszTableName).c_str(),
OGRPGEscapeString(hPGConn, pszXML).c_str());
hResult = OGRPG_PQexec(hPGConn, osCommand.c_str());
OGRPGClearResult(hResult);

CPLDestroyXMLNode(psRoot);
CPLFree(pszXML);
}
else
{
CPLString osCommand;
osCommand.Printf("DELETE FROM ogr_system_tables.metadata WHERE "
"schema_name = %s AND table_name = %s",
OGRPGEscapeString(hPGConn, pszSchemaName).c_str(),
OGRPGEscapeString(hPGConn, pszTableName).c_str());
PGresult *hResult =
OGRPG_PQexec(hPGConn, osCommand.c_str(), false, true);
OGRPGClearResult(hResult);
}
}

/************************************************************************/
/* GetMetadataDomainList() */
/************************************************************************/

char **OGRPGTableLayer::GetMetadataDomainList()
{
LoadMetadata();

if (m_pszTableDescription == nullptr)
GetMetadata();
if (m_pszTableDescription != nullptr && m_pszTableDescription[0] != '\0')
Expand All @@ -250,6 +446,8 @@ char **OGRPGTableLayer::GetMetadataDomainList()

char **OGRPGTableLayer::GetMetadata(const char *pszDomain)
{
LoadMetadata();

if ((pszDomain == nullptr || EQUAL(pszDomain, "")) &&
m_pszTableDescription == nullptr)
{
Expand Down Expand Up @@ -289,6 +487,8 @@ char **OGRPGTableLayer::GetMetadata(const char *pszDomain)
const char *OGRPGTableLayer::GetMetadataItem(const char *pszName,
const char *pszDomain)
{
LoadMetadata();

GetMetadata(pszDomain);
return OGRLayer::GetMetadataItem(pszName, pszDomain);
}
Expand All @@ -299,7 +499,11 @@ const char *OGRPGTableLayer::GetMetadataItem(const char *pszName,

CPLErr OGRPGTableLayer::SetMetadata(char **papszMD, const char *pszDomain)
{
LoadMetadata();

OGRLayer::SetMetadata(papszMD, pszDomain);
m_bMetadataModified = true;

if (!osForcedDescription.empty() &&
(pszDomain == nullptr || EQUAL(pszDomain, "")))
{
Expand Down Expand Up @@ -337,17 +541,23 @@ CPLErr OGRPGTableLayer::SetMetadataItem(const char *pszName,
const char *pszValue,
const char *pszDomain)
{
LoadMetadata();

if ((pszDomain == nullptr || EQUAL(pszDomain, "")) && pszName != nullptr &&
EQUAL(pszName, "DESCRIPTION") && !osForcedDescription.empty())
{
pszValue = osForcedDescription;
}

OGRLayer::SetMetadataItem(pszName, pszValue, pszDomain);
m_bMetadataModified = true;

if (!bDeferredCreation && (pszDomain == nullptr || EQUAL(pszDomain, "")) &&
pszName != nullptr && EQUAL(pszName, "DESCRIPTION"))
{
SetMetadata(GetMetadata());
}

return CE_None;
}

Expand Down Expand Up @@ -506,7 +716,7 @@ int OGRPGTableLayer::ReadTableDefinition()
CPLDebug("PG", "Primary key name (FID): %s, type : %s",
osPrimaryKey.c_str(), pszFIDType);
if (EQUAL(pszFIDType, "int8"))
SetMetadataItem(OLMD_FID64, "YES");
OGRLayer::SetMetadataItem(OLMD_FID64, "YES");
}
}
else if (PQntuples(hResult) > 1)
Expand Down Expand Up @@ -1547,7 +1757,7 @@ OGRErr OGRPGTableLayer::ICreateFeature(OGRFeature *poFeature)

/* Auto-promote FID column to 64bit if necessary */
if (pszFIDColumn != nullptr && !CPL_INT64_FITS_ON_INT32(nFID) &&
GetMetadataItem(OLMD_FID64) == nullptr)
OGRLayer::GetMetadataItem(OLMD_FID64) == nullptr)
{
poDS->EndCopy();

Expand All @@ -1568,7 +1778,7 @@ OGRErr OGRPGTableLayer::ICreateFeature(OGRFeature *poFeature)
}
OGRPGClearResult(hResult);

SetMetadataItem(OLMD_FID64, "YES");
OGRLayer::SetMetadataItem(OLMD_FID64, "YES");
}

if (bFirstInsertion)
Expand Down

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