Function _Constraint_Create

src/commands/cmd_constraint.c:231–375

GRAPH.CONSTRAIN CREATE UNIQUE/MANDATORY [NODE label / RELATIONSHIP type] PROPERTIES prop_count prop0, prop1...

// GRAPH.CONSTRAIN <key> CREATE UNIQUE/MANDATORY [NODE label / RELATIONSHIP type] PROPERTIES prop_count prop0, prop1...
static bool _Constraint_Create
(
	RedisModuleCtx *ctx,    // redis module context
	RedisModuleString *key, // graph key to operate on
	ConstraintType ct,      // constraint type
	GraphEntityType et,     // entity type
	const char *lbl,        // label / rel-type
	uint8_t n,              // properties count
	const char **props      // properties
) {
	bool res = true;
	const char *error_msg = "Constraint creation failed";

	// get or create graph
	GraphContext *gc = GraphContext_Retrieve(ctx, key, false, true);
	if(gc == NULL) {
		return false;	
	}

	// set graph context in query context TLS
	// this is required in case the undo-log needs to be applied
	// TODO: find a better way
	QueryCtx_SetGraphCtx(gc);

	Graph *g = GraphContext_GetGraph(gc);

	// acquire graph write lock
	Graph_AcquireWriteLock(gc->g);

	//--------------------------------------------------------------------------
	// convert attribute name to attribute ID
	//--------------------------------------------------------------------------

	Attribute_ID attr_ids[n];
	for(uint i = 0; i < n; i++) {
		attr_ids[i] = FindOrAddAttribute(gc, props[i], true);
	}

	//--------------------------------------------------------------------------
	// check for duplicates
	//--------------------------------------------------------------------------

	// sort the properties for an easy comparison later
	bool dups = false;
	qsort(attr_ids, n, sizeof(Attribute_ID), _cmp_Attribute_ID);
	for(uint i = 0; i < n - 1; i++) {
		if(attr_ids[i] == attr_ids[i+1]) {
			dups = true;
			break;
		}
	}

	// duplicates found, fail operation
	if(dups) {
		error_msg = "Properties cannot contain duplicates";
		res = false;
		goto cleanup;
	}